XIII General Meeting of the Russian Mineralogical Society and the Fedorov Session 3031233891, 9783031233890

Table of contents :
Preface
Contents
Fundamental Issues of Mineralogy, Mineral Diversity and Evolution of Mineral Formation
Priorities of Modern Mineralogy
1 Introduction. About the Priority Problems of Mineralogy
2 Priority Issues in Mineralogical Science
3 Comments and Remarks on the “Mineralogical List”
4 About Possible Additions to the List
5 Conclusion
References
E. S. Fedorov’s “Drusites”: Metamorphic Reaction Structures in Paleoproterozoic Metagabbronorites of the Belomorian Province of the Fennoscandian Shield
1 Introduction
2 Geology and Petrography
3 Thermobarometry
4 Discussion
5 Conclusions
References
Calcium and Cuprum Oxalates in Biofilms on the Surface of the Scoria Cones of Tolbachik Volcano
1 Introduction
2 Methods and Approaches
3 Results and Discussion
4 Conclusions
References
Heterogeneous Mineral Complex in Bottom Sediments North-Western Black Sea
1 Introduction
1.1 Materials and Methods
2 Results and Its Discussion
3 Conclusion
References
Monticellite from Spurrite Marbles of the Kochumdek Contact Aureole
1 Introduction
2 Materials and Methods
3 Kochumdek Aureole
4 Monticellite from Kochumdek Marbles
4.1 Grain Morphology
4.2 Mineral Chemistry
5 Discussion and Conclusions
References
The Association of Henritermierite with Mg-Rich Vesuvianite in Mn Ores: Indicator Significance and an Example of Crystal Chemical Selectivity
1 Introduction
2 Methods and Approaches
3 Conclusions
References
Microbial Biomineralization: Morphogenetic and Crystal Chemical Patterns
1 Introduction
2 Methods and Approaches
3 Results and Discussion
4 Conclusions
References
Synthetic Uranyl Compounds: Chemical View on Natural Processes of Uranium Ore Alteration
1 Introduction
2 Discussion
References
Sulfide-Oxide Mineral Formation During Melt Differentiation in the Intermediate Chamber
1 Introduction
2 Results
3 Discussion of Results and Conclusion
References
Native Niobium in the Rocks of the Bobruisk Marginal Salient of the Eastern European Craton Foundation
1 Introduction
2 Actual Materials and Methods
3 The Results
4 Conclusion
References
Solid-Phase Gold Transformation in Contact Interactions
1 Introduction
2 Actual Data and Methods
3 Results and Discussion
4 Conclusions
References
Thiozincate Phase Na2Zn4S5 in Spurrite Marbles at Tulul Al Hamam, Daba-Siwaga Pyrometamorphic Complex, Jordan: Chemical and Raman Data
1 Introduction
2 Analytical Methods
3 Spurrite Marbles
4 Chemical Composition of Sphalerite and Na-Zn-Sulfide
5 Raman Spectroscopy
6 The System ZnS-Na2S (Experimental Data)
7 Short Remarks
References
Trace Element Impact on the Corundum Morphology
1 Introduction
2 Results
3 Discussion and Conclusion
References
Hydrothermal Tourmaline from the Girvas Paleovolcano (Onega basin, Karelian Craton): Morphology and Chemical Composition
1 Introduction
2 Materials and Methods
3 Results and Discussion
References
Ti-Fe-Nb Mineral Phases from the Boxiton Bearing Weather Bark of the Verkhne-Shchugorsky Deposit (Middle Timan)
1 Introduction
2 Research Methodology
3 Results and Discussion of Results
References
Scandium Garnets from Chloritolites, South Ural
1 Introduction
2 Materials and Methods
3 Results and Discussion
References
Minerals - Indicators of Petro- and Ore Genesis and New Methods of Its Identification
Compositional Evolution of Ree- and Ti-Bearing Accessory Minerals in Metamorphic Schists of the Atomfjella Series, Western Ny Friesland, Spitsbergen
1 Introduction
2 Geological Setting
3 Analytical Methods
4 Petrography
5 Accessory Minerals and the Sequence of Their Formation
6 Conclusion
References
Sulfostannates of Zwitter-Tourmalinite Complexes Accompanying the Lithium-Fluoric Granites (On the Example of Pravourmiysky Rare-Metal-Tin Deposit)
1 Introduction
2 Materials and Methods
3 Results
4 Discussion
5 Conclusions
References
Mineralogical Features of Columbite from Rare-Metal Granites and Its Isomorphism
1 Introduction
2 Brief Geologic-Mineralogical Description of the Zashikhinsky Massif
3 Materials and Methods
4 Features of Columbite Composition
5 Discussion
6 Conclusions
References
The Inclusions in Zircon of the Kozhim Massif (The Subpolar Urals)
1 Introduction
2 Materials and Methods
3 Results and Discussion
4 Conclusions
References
Method for Multiple Analysis of Indicator Mineral Compositions of Kimblites to Estimate the Presence of Type IIa Large Diamonds
1 Introduction
2 Research Methods and Materials
3 Research Results
4 The Discussion of the Results
5 Conclusions
References
Mineral Inclusions in Irghizites and Microirghizites (Zhamanshin Astroblem, Kazakhstan)
1 Introduction
2 Methods and Samples
3 Results and Discussion
4 Conclusions
References
Minerals-Indicators of Fluids Compositions in the Metabasites (by Experimental Data)
1 Introduction
2 Technique and Methodology of Experiments
3 Experimental Results
4 Mineral Compositions
5 Conclusion
References
Trace Elements in Amphiboles from Marbles of Luk Yen Ruby and Gem Spinel Deposit, North Vietnam
1 Introduction
2 Materials and Methods
3 Object of Study
4 Amphibole Chemical Composition
5 The Discussion of the Results
6 Conclusion
References
Periclase from Kuhilal Deposit, Southwestern Pamirs as a Result of Magnesian Solfats and Chlorites Metamorphism
1 Factual Materials and Research Methods
2 Geological Position of the Research Object
3 Results
4 The Discussion of the Results
5 Conclusion
References
Monazit of Pizhemskogo, Yarega Deposits and Occurrence of Ichetju, Experience of Chemical Dating
1 Factual Materials and Research Methods
2 The Yarega Oil-Titanium Giant Deposit
3 The Pizhemskoye Deposit of Pseudorutile-Leucoxene-Quartz Sandstones
4 Ichetyu Polymineral Occurrense (Middle Timan)
5 The Discussion of the Results
References
Filament Crystals of Isoferroplatinum
1 Introduction
2 Actual Materials and Methods
3 Results
4 The Discussion of the Results
5 Conclusion
References
Compositional Zoning of Spessartine-Grossular Garnets in the Archean Metavolcanics of the Central Bundelkhand Greenstone Complex, Bundelkhand Craton, Indian Shield
1 Introduction
2 Geological Sketch
3 Working Methods
4 Petrography
5 Chemical Composition, Zoning and Internal Structure of Pomegranates
6 Conclusion
References
Anomalous Composition of Zircon from Leucogranites of the Belokurikhinsky Massif, Altai
1 Introduction
2 Factual Material and Research Methods
3 Results
4 Conclusion
References
Chrome-Spinelides from Layered Intrusions of the Paleoproterozoic Fennoscandian Shield as Indicators of Petro - and Ore Genesis
1 Introduction
2 Methods of Analysis
3 Brief Geological-Petrological Characteristic
4 Analysis and Discussion
5 Conclusions
References
Composition of Volatile Components in Polycrystalline Diamond Aggregates from Mir and Udachnaya Kimberlite Pipes, Yakutia
1 Introduction
2 Samples and Methods
3 Results
3.1 IR Spectroscopy Results
3.2 Raman Spectroscopy Results
3.3 TEM Analysis
3.4 Gas Chromatography-mass Spectrometry (GC–MS) Results
4 Discussion and Conclusions
References
Nature of Daughter Mineral Phases of Melt Inclusions
1 Introduction
2 Results
3 Conclusion
References
Gold Nuggets-Indicators of the Frontal Part of the Ore Column of the Deposits of the Amur Province
1 Introduction
2 Geological and Structural Position and Gold Content of the Amur Province
3 Gold Nuggets
4 Conclusion
References
Trace Element (V, Sc, Ga) Composition of Zonal Pyroxenes–As the Basis for the Reconstruction of Crystallization Conditions of Basaltic Magmas
1 Introduction
2 Sampling and Methods
3 Results and Discussion
References
Compositions of Pyroxenes from Kimberlites and Eclogite Xenoliths of the Katoka Pipe (Angola)
1 Introduction
2 Research Methods and Materials
3 Research Results
4 Conclusion
References
Mineralogy and Formation Conditions of Strategic Mineral Raw Materials Deposits
First Finds of Weissbergite (TlSbS2) and Avicennite (Tl2O3) in Yakutia
1 Introduction
2 Geological Description and Mineral Composition of the Khokhoy Field
3 Research Methods
4 Results of the Study
5 Discussion
6 Conclusions
References
Lithochemical Characteristics of Dome Deposits Shungite Rocks of Onega Structure
1 Introduction
2 Materials and Methods
3 Results and Discussion
4 Conclusion
References
Petrological and Geochemical Features and Age of the Granitoid Complexes of the Kordonnoe Deposit as Indicators of the Geodynamic Conditions of Its Formation (Primorsky Krai, Russia)
1 Introduction
2 Materials and Methods
3 Results
4 Discussion of Results and Conclusions
References
Rare Minerals in the Ore-bearing Sediments of the Hydrothermal Cluster Pobeda (17°07.45´N. - 17°08.7´N MAR)
1 Introduction
2 Materials and Methods
3 Results of Studies
4 The Discussion of Results
5 Conclusion
References
On the Genesis of Gold Mineralization in the Central Part of Hautavaara Greenstone Structure (Karelia)
1 Introduction
2 Research Methods
3 Brief Geological Characteristics
4 Discussion of Results. Typification of Ore Mineralization and Patterns of Its Manifestation
5 Parameters of the Fluid Regime of Ore Formation
6 Conclusion
References
Gold-Bismuth Mineralization of Pasechnoe Deposit (South Sikhote-Alin)
1 Introduction
2 Research Object
3 Results and Discussion
4 Conclusion
References
New Data on Ore Minerals of the Konder Deposit
1 Introduction
2 Actual Materials and Methods
3 Results and Discussion
References
Telluride Mineralization of Gold Deposits of the Aldan Shield
1 Introduction
2 Actual Materials and Methods
3 Results
4 Conclusion
References
Rare and Unknown Secondary Minerals of the Khangalas Ore Cluster (NE Russia)
1 Introduction
2 Factual Material and Methods
3 Results and Discussion
4 Conclusions
References
New Data on the Mineralogy of Copper-Molybdenum-Porphyry and Associated Gold-Base Metal Mineralization of the Lobash and Lobash-1 Deposits, Karelia
1 Introduction
2 Geological Structure of the Lobash Ore Field
3 Materials and Methods
4 Results
4.1 Lobash Deposit
4.2 Lobash-1 Deposit
5 Discussion
6 Conclusions
References
Mineralogy of Altered Rocks and Ores of the Multistage Kekura Intrusion-Related Gold Deposit, Western Chukotka, Russia
1 Geological Setting
2 Alterations
3 Mineralization
4 Conclusion
References
Major and Trace Element Signatures in Lagoon Vivianite: A Case Study from the Kerch Ooidal Ironstones
1 Introduction
2 Kerch Ooidal Ironstones
3 Materials and Methods
4 Results
5 Discussion
6 Conclusions
References
Influence of Exogenous Conditions on the Transformation of Native Gold
1 Introduction
2 Factual Material and Methods
3 Results
4 Conversion of Native Gold in a Hydrodynamic Medium
5 Transformation of Native Gold in an Aeolian Setting
6 Discussion of the Results
7 Conclusion
References
Noble Metals and Carbon Substances in the Uranium and Rare Metal Deposits of Central Asia
1 Introduction
2 Actual Materials and Methods
3 Main Results and Discussion
4 Conclusion
References
Mineral Associations of Gold Occurences in the Taimyr-Severnaya Zemlya Orogen as Indicators of Major Deposits in the Central Sector of the Russian Arctic
1 Introduction
2 Results
3 Conclusion
References
Garnet as a Promising Source of Rare Metals
1 Introduction
2 Prospects Studied
3 Materials and Methods
4 Results and Its Discussion
5 Conclusions
References
Comparative Analysis of Micropolicrystalline Diamonds Type Carbonados and Their Synthetic Analogues
1 Introduction
2 Factual Material and Methods
3 Results and Discussion
4 Conclusion
References
Smectite in the Triassic Greywacke and its Influence on Reservoir Properties
1 Introduction
2 Materials and Methods
3 Results
4 Conclusions
References
Problems of Applied (Technological and Ecological) Mineralogy and Geochemistry
Micron-Sized Mineral Inclusions and Impurity Phases in Graphite from the Ihala Deposit, Karelia, Russia
1 Introduction
2 Materials and Methods
3 Results
4 Conclusions
References
Mineralogical-Technological Characteristics of the South-Western Lupikko Fluorite Occurrences, Republic of Karelia
1 Introduction
2 Materials and Methods
3 Results
4 Discussion
5 Conclusions
References
Integrated Approach to Determining the Phase Composition of Ores
1 Introduction
2 Materials and Methods
3 Results and Discussion
4 Conclusions
References
The Chemical Composition of Water and Sediments of an Arctic Mountain Lake in the Zone of Influence of Sewage of Apatite-Nepheline Production
1 Introduction
2 Materials and Methods
3 Results and Discussion
4 Conclusion
References
Technological Mineralogy of Chrome Ore
1 Introduction
2 Object and Methods of Research
3 Results of Studies
4 Conclusion
References
Influence of the Chemical Composition of Minerals on the Mechanical Properties of Basalt Continuous Fibers
1 Introduction
2 Materials and Methods
2.1 Preparation of Glasses
2.2 X-Ray Fluorescence Analysis
2.3 X-Ray Diffraction
2.4 Measuring of Diameters
2.5 Measuring of Mechanical Properties
2.6 Raman Spectroscopy
3 Result and Discussion
4 Conclusion
References
High-Iron Bauxites: Composition Features and Processing Technology (The Middle Timan)
1 Introduction
2 Geological Setting
3 Materials and Methods
4 Results and Its Discussion
5 Conclusion
References
Effect of Structure and Stereochemistry on Metakaolin Reactivity when Geopolymerization
1 Introduction
2 Materials and Methods
3 Results and Discussions
4 Conclusions
References
Rare-metal Weathered Crust Saprolite: Material Composition and Selection of Rational Flow Chart
1 Introduction
2 Approaches and Methods
3 Results and Discussion
4 Conclusions
References
Mineral-Geochemical Evaluation Criteria of Ecological Situation in Territories of Mining Profile
1 Introduction
2 Approaches and Methods
2.1 The System of Criteria Used for Ecological-Geochemical Assessment of the Environment
2.2 Anthropogenic Controls in the Analysis of the Ecological Condition of Urbanized Territories
3 Results and Discussion
4 Conclusions
References
Sorption of Phosphorus on Leucoxene: Experimental Studies
1 Introduction
2 Object and Methods
3 Results and Its Discussion
4 Conclusions
References
Physico-chemical Properties of Analcime-Bearing Rocks of Timan
1 Introduction
2 Objects and Research Methods
3 Experiments on Sorption of Radionuclides
4 Experiments on the Treatment of Domestic and Waste Waters from Industrial Enterprises
5 Results and Discussion. Phase and Chemical Compositions
6 Textural Characteristics
7 Sorption of Pollutants in the Treatment of Drinking Water and Waste Water from Enterprises
8 Sorption of Natural Radionuclides
9 Conclusions
References
Reflection of Geochemical Features of the Environment on the Bone Tissue of Krasnoyarsk Residents
1 Introduction
2 Materials and Methods
3 Discussion of the Results
4 Conclusion
References
Natural Stone in Art and Architecture. Modern Methods of Research in the Field of Gems, Semi-precious Stone Raw Materials and Geology
Acoustopolariscopy is the Method for Determining Mineral Samples and Rocks Quality
1 Introduction
2 Acoustopolariscopy Method
3 Acoustopolariscopy of Minerals
4 German Superdeep (KTB-HB)
5 Conclusion
References
Turning the Thunder Stone into the Population of the Bronze Horseman Monument in St. Petersburg (Experience of Historical Reconstruction)
1 Introduction
2 Formulation of the Problem
3 Research Results
4 The Discussion of the Results
5 Conclusion
References
Nephrite of Bazhenovskoye Chrysotile-Asbestos Deposit, the Middle Urals: Composition, Properties and Quality
1 Introduction
2 Manifestation of Nephrite
3 Composition and Properties of Nephrite
4 Nephrite Formation Features
5 Conclusion
References
Mineralogy and Gemmology of a New Jewelry Stone of Raiizite
1 Introduction
2 Factual Materials
3 Research Methods
4 Research Results
5 Conclusion
References
Diamond Fields of the Nezametnoe Area (Primorye, Far East of Russia)
1 Introduction
2 Actual Materials and Methods
3 Results and Discussion
4 Conclusion
References
Mineral Composition of Jewelry Septaries of Morocco
1 Introduction
2 Factual Material and Research Methods
3 Research Results
4 Conclusion
References
Determination of the Validity of a Collectional Malachite Deposit by an X-ray Fluorescent Analysis
1 Introduction
2 Research Methods
3 Factual Materials
4 Results
5 The Discussion of the Results
6 Conclusion
References
The Most Urban Stone: Quartzite Sandstone of the Petrozavodsk Suite
1 Introduction
2 Chemical Composition of the Kamennobor Quartzite Sandstone, Geological Structure and a Brief History of the Study of the Deposit
3 Development History of the Kamennoborskoye Field
4 Application of Kamennobor Quartzite Sandstones in Petrozavodsk
5 Conclusion
References
Patterns of the Hydrogen Distribution in the Volume of Natural Diamonds: Causes and Consequences
1 Introduction
2 General Regularities and Their Discussion
3 Conclusion
References
Fedorov Session: Mineralogical Crystallography, Crystallochemistry and New Minerals; History of Science, Modification and Popularisation of Natural Science Knowledge
Centurial Discussion on Building Units in Crystal Growth: Kossel vs Balarev
1 Introduction Background
2 Non-classical Models of Crystal Nucleation
3 Non-classical Crystal Growth
4 Conclusion
References
Crystal Chemistry of Biofilm and Synthetic Oxalates of the Humboldtine Group
1 Introduction
2 Methods and Approaches
3 Results and Discussion
3.1 Formation of Oxalates of the Humboldtine Group Under the A.niger Action
3.2 Formation of Oxalates of the Humboldtine Group in Synthetic Experiments
References
Some Structural Features of Monodisperse Spherical Silica Particles - Structural Units of Opal Matrices
1 Introduction
2 Problem of Spherical of Silica
3 Determination of Density of Silica Particles by Measuring the Volume of the Formed Supramolecular Structure
4 Determination of Density of Silica Particles Proceeding from a Comparison of the Experimentally Obtained Rate of Deposition of the Particles and Their Sizes
5 Estimation of Porosity of Particles Based on Comparison of Their Values of the Specific Surface Area with Sizes Obtained by the Method of Atomic Force Microscopy
6 Conclusion
References
Fedorite in Charoite and Brookite-Feldspar-Quartz Rocks of the Alkaline Murun Complex
1 Introduction
2 Fedorite from the Irkutskiy District of Murun Complex
3 Fedorite from the Yakutskiy District of Murun Complex
4 Fedorite from the Gavrilovskaya Zone of Murun Complex
5 Conclusions
References
Solid Phase Relationships in Systems of Amino Acid Enantiomers in Connection with Their Participation in Geological and Technological Processes
1 Introduction
2 Objects and Research Methods
3 Results and Discussion
4 Conclusion
References
Investigation of Substance Aggregation Effect on Variation of No3− Anions and Oh-Groups Vibrations in Aqueous Solution by Raman Spectroscopy
1 Introduction
2 Experiment Scheme
3 Experimental Results and Their Discussion
4 Conclusion
References
57Fe Mössbauer Spectroscopy of Dispersed Fe-Mn Carbonate Ores (The Pay-Khoy Ridge, Russia)
1 Introduction
2 Samples and Methods
3 Results and Discussion
4 Conclusion
References
Experience of Calculation Factor of the Structural Complexity Coefficient for Structural Challenges Describe the Regularities of Genetic Inheritance Structure Under Crystallization of Berillian Indialite
1 Introduction
2 Experimental Part. Calculation Principles and Their Interpretation
3 Methods and Conditions of Synthesis
4 Results and Discussion
5 Conclusion
References
Nano- and Micromorphological Evidence of Colloidal Fluid Structure in Inclusions of Aquamarine Crystals
1 Introduction
2 Methods
3 Results and Discussion
4 Conclusion
References
Order-Disorder in Charoite and Denisovite Structures
1 Introduction
2 Order-Disorder in Charoite Structure
3 Order-Disorder in Denisovite Structure
References
Raman Spectroscopy of Isomorphic Substitutions in the Structure of Jarosite Formed During Pressure Oxidation of Refractory Gold Ores
1 Introduction
2 Actual Data and Methods
3 Results and Discussion
4 Conclusion
References
Crystal Chemistry of Glaukonite from the South-East of the Bashkortostan Republic (Yangyssko-Bayguskarovskaya Zone)
1 Introduction
2 Materials and Methods
3 Results and Discussion
4 Conclusions
References
The First Results of the Habit Estimate of Real Crystal Octahedra
1 Introduction
2 Materials and Methods
3 Results and Discussion
4 Conclusion
References
The Leningrad Mining Institute Scientists Contribution to the Non-ferrous Metallurgy Ore Base Creation During the Second World War
1 Introduction
2 Creating of Aluminum Ores Base
3 Professor a. Boldyrev and His Contribution to the Tin Ore Base Creation
4 The LGI Nickel Group Activity
5 Conclusion
References
Nesquehonite from the Kimberlite Pipe Obnazhennaya: Thermal Analysis and Infrared Spectroscopy
1 Introduction
2 Factual Material and Research Methods
3 Research Results
4 Discussion of the Results. Conclusions
References
New Data on the Crystal Chemistry of Technogenic Minerals from the Burned Dumps of Chelyabinsk Coal Basin
1 Introduction
2 Materials and Methods
3 Results
4 Discussion and Conclusion
References
Author Index

Citation preview

Springer Proceedings in Earth and Environmental Sciences

Yuri Marin   Editor

XIII General Meeting of the Russian Mineralogical Society and the Fedorov Session

Springer Proceedings in Earth and Environmental Sciences Series Editors Natalia S. Bezaeva, The Moscow Area, Russia Heloisa Helena Gomes Coe, Niterói, Rio de Janeiro, Brazil Muhammad Farrakh Nawaz, Department of Forestry and Range Management, University of Agriculture, Faisalabad, Pakistan

The series Springer Proceedings in Earth and Environmental Sciences publishes proceedings from scholarly meetings and workshops on all topics related to Environmental and Earth Sciences and related sciences. This series constitutes a comprehensive up-to-date source of reference on a field or subfield of relevance in Earth and Environmental Sciences. In addition to an overall evaluation of the interest, scientific quality, and timeliness of each proposal at the hands of the publisher, individual contributions are all refereed to the high quality standards of leading journals in the field. Thus, this series provides the research community with well-edited, authoritative reports on developments in the most exciting areas of environmental sciences, earth sciences and related fields.

More information about this series at https://link.springer.com/bookseries/16067

Yuri Marin Editor

XIII General Meeting of the Russian Mineralogical Society and the Fedorov Session

123

Editor Yuri Marin The Russian Mineralogical Society St. Petersburg, Russia

ISSN 2524-342X ISSN 2524-3438 (electronic) Springer Proceedings in Earth and Environmental Sciences ISBN 978-3-031-23389-0 ISBN 978-3-031-23390-6 (eBook) https://doi.org/10.1007/978-3-031-23390-6 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Preface

The XIII General Meeting of the Russian Mineralogical Society (the oldest existing mineralogical society in the world; it will celebrate its 205th anniversary on 19 January 2022) was held at St. Petersburg Mining University on 5–7 October 2021. The proceedings of the international scientific conference “XIII General Meeting of the Russian Mineralogical Society and the Fedorov Session” is dedicated to the discussion of the results of fundamental and applied research in a wide range of related disciplines, covering the study of minerals and mineraloids, rocks, ferrous and non-ferrous raw materials, natural mineral formations as applied materials and cultural objects, and artificial analogs of minerals and rocks, used in various fields of human activity. The chapters of the book represent the thematic sections: The XIII General Meeting and the Fedorov Session: fundamental issues of mineralogy, mineral diversity and evolution of mineral formation; minerals—indicators of petro- and ore genesis and new methods of its identification; mineralogy and formation conditions of strategic minerals deposits; problems of applied (technological and ecological) mineralogy and geochemistry; natural stone in art and architecture. Modern methods of research in the field of gems, semi-precious stone raw materials and gemology; new achievements in the field of mineralogical crystallography, crystal chemistry and mineralogy of new minerals; history of science, museumification and popularization of the natural science knowledge. Proceedings of the participants of the XIII General Meeting of the Russian Mineralogical Society and the Fedorov Session is given in the chapters of this book. We hope that they will be interesting to a wide range of specialists. Yury Borisovich Marin

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Contents

Fundamental Issues of Mineralogy, Mineral Diversity and Evolution of Mineral Formation Priorities of Modern Mineralogy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. M. Askhabov E. S. Fedorov’s “Drusites”: Metamorphic Reaction Structures in Paleoproterozoic Metagabbronorites of the Belomorian Province of the Fennoscandian Shield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. Ya. Azimov Calcium and Cuprum Oxalates in Biofilms on the Surface of the Scoria Cones of Tolbachik Volcano . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. A. Chernyshova, O. S. Vereshchagin, M. S. Zelenskaya, D. Yu. Vlasov, O. V. Frank-Kamenetskaya, and D. E. Himelbrant

3

9

17

Heterogeneous Mineral Complex in Bottom Sediments NorthWestern Black Sea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . O. M. Dara, L. E. Reykhard, and M. D. Kravchishina

25

Monticellite from Spurrite Marbles of the Kochumdek Contact Aureole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. S. Deviatiiarova

35

The Association of Henritermierite with Mg-Rich Vesuvianite in Mn Ores: Indicator Significance and an Example of Crystal Chemical Selectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. V. Chukanov, V. N. Ermolaeva, D. A. Varlamov, and E. Jonsson Microbial Biomineralization: Morphogenetic and Crystal Chemical Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . O. V. Frank-Kamenetskaya and D. Y. Vlasov

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Synthetic Uranyl Compounds: Chemical View on Natural Processes of Uranium Ore Alteration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. V. Gurzhiy, O. S. Tyumentseva, I. V. Kornyakov, and S. V. Krivovichev

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Sulfide-Oxide Mineral Formation During Melt Differentiation in the Intermediate Chamber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. G. Kovalev and S. S. Kovalev

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Native Niobium in the Rocks of the Bobruisk Marginal Salient of the Eastern European Craton Foundation . . . . . . . . . . . . . . . . . . . . . . . . . . I. V. Levitskiy, V. I. Levitskiy, L. A. Pavlova, and M. V. Lukashova

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Solid-Phase Gold Transformation in Contact Interactions . . . . . . . . . . . V. I. Rozhdestvina Thiozincate Phase Na2Zn4S5 in Spurrite Marbles at Tulul Al Hamam, Daba-Siwaga Pyrometamorphic Complex, Jordan: Chemical and Raman Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. V. Sharygin, E. V. Sokol, and E. N. Nigmatulina Trace Element Impact on the Corundum Morphology . . . . . . . . . . . . . . E. S. Sorokina

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88 97

Hydrothermal Tourmaline from the Girvas Paleovolcano (Onega basin, Karelian Craton): Morphology and Chemical Composition . . . . . 103 E. N. Svetova and S. A. Svetov Ti-Fe-Nb Mineral Phases from the Boxiton Bearing Weather Bark of the Verkhne-Shchugorsky Deposit (Middle Timan) . . . . . . . . . . . . . . 110 O. V. Udoratina, D. A. Varlamov, B. A. Makeev, V. P. Lutoev, and A. S. Shuyskiy Scandium Garnets from Chloritolites, South Ural . . . . . . . . . . . . . . . . . 117 D. A. Varlamov and V. V. Murzin Minerals - Indicators of Petro- and Ore Genesis and New Methods of Its Identification Compositional Evolution of Ree- and Ti-Bearing Accessory Minerals in Metamorphic Schists of the Atomfjella Series, Western Ny Friesland, Spitsbergen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 S. A. Akbarpuran Haiyati, Yu. L. Gulbin, A. N. Sirotkin, and I. M. Gembitskaya Sulfostannates of Zwitter-Tourmalinite Complexes Accompanying the Lithium-Fluoric Granites (On the Example of Pravourmiysky Rare-Metal-Tin Deposit) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 V. I. Alekseev

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Mineralogical Features of Columbite from Rare-Metal Granites and Its Isomorphism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 N. V. Alymova and N. V. Vladykin The Inclusions in Zircon of the Kozhim Massif (The Subpolar Urals) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 Yu. V. Denisova Method for Multiple Analysis of Indicator Mineral Compositions of Kimblites to Estimate the Presence of Type IIa Large Diamonds . . . . . 156 A. S. Ivanov and V. N. Zinchenko Mineral Inclusions in Irghizites and Microirghizites (Zhamanshin Astroblem, Kazakhstan) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 E. S. Sergienko, S. J. Janson, A. Esau, Hamann, F. Kaufmann, L. Hecht, V. V. Karpinsky, E. V. Petrova, and P. V. Kharitonskii Minerals-Indicators of Fluids Compositions in the Metabasites (by Experimental Data) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 L. I. Khodorevskaya Trace Elements in Amphiboles from Marbles of Luk Yen Ruby and Gem Spinel Deposit, North Vietnam . . . . . . . . . . . . . . . . . . . . . . . . . . . 186 K. A. Kuksa, P. B. Sokolov, M. E. Klimacheva, S. G. Skublov, and I. S. Sergeev Periclase from Kuhilal Deposit, Southwestern Pamirs as a Result of Magnesian Solfats and Chlorites Metamorphism . . . . . . . . . . . . . . . . . . 194 A. K. Litvinenko, D. A. Litvinenko, and A. F. Fedorov Monazit of Pizhemskogo, Yarega Deposits and Occurrence of Ichetju, Experience of Chemical Dating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 A. B. Makeyev and A. O. Krasotkina Filament Crystals of Isoferroplatinum . . . . . . . . . . . . . . . . . . . . . . . . . . 213 A. G. Mochalov Compositional Zoning of Spessartine-Grossular Garnets in the Archean Metavolcanics of the Central Bundelkhand Greenstone Complex, Bundelkhand Craton, Indian Shield . . . . . . . . . . . . . . . . . . . . 223 O. S. Sibelev Anomalous Composition of Zircon from Leucogranites of the Belokurikhinsky Massif, Altai . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 S. G. Skublov and M. E. Mamykina Chrome-Spinelides from Layered Intrusions of the Paleoproterozoic Fennoscandian Shield as Indicators of Petro - and Ore Genesis . . . . . . . 238 V. F. Smolkin and A. V. Mokrushin

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Composition of Volatile Components in Polycrystalline Diamond Aggregates from Mir and Udachnaya Kimberlite Pipes, Yakutia . . . . . . 247 N. V. Sobolev, A. A. Tomilenko, T. A. Bulbak, A. M. Logvinova, and R. Wirth Nature of Daughter Mineral Phases of Melt Inclusions . . . . . . . . . . . . . 254 S. V. Sokolov Gold Nuggets-Indicators of the Frontal Part of the Ore Column of the Deposits of the Amur Province . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261 V. A. Stepanov Trace Element (V, Sc, Ga) Composition of Zonal Pyroxenes–As the Basis for the Reconstruction of Crystallization Conditions of Basaltic Magmas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269 S. A. Svetov and S. Y. Chazhengina Compositions of Pyroxenes from Kimberlites and Eclogite Xenoliths of the Katoka Pipe (Angola) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 V. N. Zinchenko, A. S. Ivanov, L. P. Nikitina, J. T. Felix, and T. M. Vunda Mineralogy and Formation Conditions of Strategic Mineral Raw Materials Deposits The First Finds of Weissbergite (Tlsbs2) and Avicennite (Tl2o3) in Yakutia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287 G. S. Anisimova, L. A. Kondratieva, and V. N. Kardashevskaia Lithochemical Characteristics of Dome Deposits Shungite Rocks of Onega Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 Yu. E. Deines Petrological and Geochemical Features and Age of the Granitoid Complexes of the Kordonnoe Deposit as Indicators of the Geodynamic Conditions of Its Formation (Primorsky Krai, Russia) . . . . . . . . . . . . . . 300 D. G. Fedoseev, V. A. Pakhomova, V. B. Tishkina, and V. V. Gusarova Rare Minerals in the Ore-bearing Sediments of the Hydrothermal Cluster Pobeda (17°07.45´N. - 17°08.7´N MAR) . . . . . . . . . . . . . . . . . . . 308 I. F. Gablina, O. M. Dara, and A. D. Lyutkevich On the Genesis of Gold Mineralization in the Central Part of Hautavaara Greenstone Structure (Karelia) . . . . . . . . . . . . . . . . . . . . . . 318 F. A. Gordon and A. V. Dmitrieva Gold-Bismuth Mineralization of Pasechnoe Deposit (South Sikhote-Alin) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326 A. A. Grebennikova

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New Data on Ore Minerals of the Konder Deposit . . . . . . . . . . . . . . . . . 332 V. V. Gusarova, V. A. Pakhomova, D. G. Fedoseev, L. F. Simanenko, and A. A. Karabtsov Telluride Mineralization of Gold Deposits of the Aldan Shield . . . . . . . 339 L. A. Kondratieva, G. S. Anisimova, and V. N. Kardashevskaia Rare and Unknown Secondary Minerals of the Khangalas Ore Cluster (NE Russia) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349 M. V. Kudrin, N. V. Zayakina, V. Yu. Fridovsky, and T. I. Vasileva New Data on the Mineralogy of Copper-Molybdenum-Porphyry and Associated Gold-Base Metal Mineralization of the Lobash and Lobash-1 Deposits, Karelia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357 L. V. Kuleshevich Mineralogy of Altered Rocks and Ores of the Multistage Kekura Intrusion-Related Gold Deposit, Western Chukotka, Russia . . . . . . . . . 365 E. V. Nagornaya and I. A. Baksheev Major and Trace Element Signatures in Lagoon Vivianite: A Case Study from the Kerch Ooidal Ironstones . . . . . . . . . . . . . . . . . . 372 A. N. Nekipelova, S. N. Kokh, E. V. Sokol, and O. A. Kozmenko Influence of Exogenous Conditions on the Transformation of Native Gold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382 Z. S. Nikiforova Noble Metals and Carbon Substances in the Uranium and Rare Metal Deposits of Central Asia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391 A. A. Potseluev Mineral Associations of Gold Occurences in the Taimyr-Severnaya Zemlya Orogen as Indicators of Major Deposits in the Central Sector of the Russian Arctic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 V. F. Proskurnin, O. V. Petrov, G. A. Palyanova, and N. S. Bortnikov Garnet as a Promising Source of Rare Metals . . . . . . . . . . . . . . . . . . . . 407 A. M. Ruchyov Comparative Analysis of Micropolicrystalline Diamonds Type Carbonados and Their Synthetic Analogues . . . . . . . . . . . . . . . . . . . . . . 414 A. E. Sukharev Smectite in the Triassic Greywacke and its Influence on Reservoir Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 420 N. N. Timonina

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Problems of Applied (Technological and Ecological) Mineralogy and Geochemistry Micron-Sized Mineral Inclusions and Impurity Phases in Graphite from the Ihala Deposit, Karelia, Russia . . . . . . . . . . . . . . . . . . . . . . . . . 429 N. S. Biske, T. P. Bubnova, and A. G. Nikiforov Mineralogical-Technological Characteristics of the South-Western Lupikko Fluorite Occurrences, Republic of Karelia . . . . . . . . . . . . . . . . 438 T. P. Bubnova and O. V. Bukchina Integrated Approach to Determining the Phase Composition of Ores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 446 V. M. Chubarov, A. V. Oshchepkova, O. Yu. Belozerova, and E. V. Kaneva The Chemical Composition of Water and Sediments of an Arctic Mountain Lake in the Zone of Influence of Sewage of ApatiteNepheline Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 453 V. A. Dauvalter, Z. I. Slukovsky, and D. B. Denisov Technological Mineralogy of Chrome Ore . . . . . . . . . . . . . . . . . . . . . . . 461 E. A. Gorbatova and B. I. Pirogov Influence of the Chemical Composition of Minerals on the Mechanical Properties of Basalt Continuous Fibers . . . . . . . . . . . . . . . . . . . . . . . . . 470 S. S. Popov and S. I. Gutnikov High-Iron Bauxites: Composition Features and Processing Technology (The Middle Timan) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 476 O. B. Kotova, Shyeng Sun, I. N. Razmyslov, and Yu. S. Simakova Effect of Structure and Stereochemistry on Metakaolin Reactivity when Geopolymerization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 484 N. I. Kozhukhova, I. V. Zhernovskaya, D. N. Danakin, A. Yu. Teslya, and M. I. Kozhukhova Rare-metal Weathered Crust Saprolite: Material Composition and Selection of Rational Flow Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 492 E. N. Levchenko Mineral-Geochemical Evaluation Criteria of Ecological Situation in Territories of Mining Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500 I. G. Spiridonov and E. N. Levchenko Sorption of Phosphorus on Leucoxene: Experimental Studies . . . . . . . . 507 A. V. Ponariadov, O. B. Kotova, Shiyong Sun, and M. Harja Physico-chemical Properties of Analcime-Bearing Rocks of Timan . . . . 514 D. A. Shushkov, O. B. Kotova, Shiyong Sun, and M. Harja

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Reflection of Geochemical Features of the Environment on the Bone Tissue of Krasnoyarsk Residents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523 T. P. Strimzha Natural Stone in Art and Architecture. Modern Methods of Research in the Field of Gems, Semi-precious Stone Raw Materials and Geology Acoustopolariscopy is the Method for Determining Mineral Samples and Rocks Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 533 F. F. Gorbatsevich Turning the Thunder Stone into the Population of the Bronze Horseman Monument in St. Petersburg (Experience of Historical Reconstruction) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 542 M. A. Ivanov, A. G. Bulakh, and G. N. Popov Nephrite of Bazhenovskoye Chrysotile-Asbestos Deposit, the Middle Urals: Composition, Properties and Quality . . . . . . . . . . . . . . . . . . . . . . 552 E. V. Kislov, M. P. Popov, and Y. V. Erokhin Mineralogy and Gemmology of a New Jewelry Stone of Raiizite . . . . . . 560 A. G. Nikolaev, M. P Popov, A. V Spirina, F. M Nurmukhametov, and L. D. Iagudina Diamond Fields of the Nezametnoe Area (Primorye, Far East of Russia) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 568 V. A. Pakhomova, D. G. Fedoseev, V. A. Solyanik, V. B. Tishkina, A. A. Karabtsov, and V. V. Gusarova Mineral Composition of Jewelry Septaries of Morocco . . . . . . . . . . . . . 575 D. A. Petrochenkov Determination of the Validity of a Collectional Malachite Deposit by an X-ray Fluorescent Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 582 M. P. Popov, A. G. Nikolaev, V. V. Kuptsova, and N. P. Gorbunova The Most Urban Stone: Quartzite Sandstone of the Petrozavodsk Suite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 588 A. V. Rachmanova Patterns of the Hydrogen Distribution in the Volume of Natural Diamonds: Causes and Consequences . . . . . . . . . . . . . . . . . . . . . . . . . . 597 E. A. Vasilev

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Fedorov Session: Mineralogical Crystallography, Crystallochemistry and New Minerals; History of Science, Modification and Popularisation of Natural Science Knowledge Centurial Discussion on Building Units in Crystal Growth: Kossel vs Balarev . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 605 A. M. Askhabov Crystal Chemistry of Biofilm and Synthetic Oxalates of the Humboldtine Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 611 A. R. Izatulina, M. A. Kuz’mina, A. V. Korneev, M. S. Zelenskaya, V. V. Gurzhiy, O. V. Frank-Kamenetskaya, and D. Yu. Vlasov Some Structural Features of Monodisperse Spherical Silica Particles - Structural Units of Opal Matrices . . . . . . . . . . . . . . . . . . . . . 619 D. V. Kamashev Fedorite in Charoite and Brookite-Feldspar-Quartz Rocks of the Alkaline Murun Complex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 628 E. V. Kaneva, T. A. Radomskaya, and Yu. Uzhegova Solid Phase Relationships in Systems of Amino Acid Enantiomers in Connection with Their Participation in Geological and Technological Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 637 E. N. Kotelnikova, A. I. Isakov, R. V. Sadovnichii, and H. Lorenz Investigation of Substance Aggregation Effect on Variation of No3− Anions and Oh-Groups Vibrations in Aqueous Solution by Raman Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 646 A. A. Kryazhev 57

Fe Mössbauer Spectroscopy of Dispersed Fe-Mn Carbonate Ores (The Pay-Khoy Ridge, Russia) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 654 V. P. Lyutoev Experience of Calculation Factor of the Structural Complexity Coefficient for Structural Challenges Describe the Regularities of Genetic Inheritance Structure Under Crystallization of Berillian Indialite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 661 S. G. Mamontova, S. Z. Zelentsov, and A. A. Dergin Nano- and Micromorphological Evidence of Colloidal Fluid Structure in Inclusions of Aquamarine Crystals . . . . . . . . . . . . . . . . . . . . . . . . . . 670 N. N. Piskunova Order-Disorder in Charoite and Denisovite Structures . . . . . . . . . . . . . 679 I. V. Rozhdestvenskaya and W. Depmeier

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Raman Spectroscopy of Isomorphic Substitutions in the Structure of Jarosite Formed During Pressure Oxidation of Refractory Gold Ores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 686 V. I. Rozhdestvina, A. S. Zavalyuev, and N. V. Mudrovskaya Crystal Chemistry of Glaukonite from the South-East of the Bashkortostan Republic (Yangyssko-Bayguskarovskaya Zone) . . . . . . . 695 Yu. S. Simakova, V. P. Lyutoev, and A. Yu. Lysiuk The First Results of the Habit Estimate of Real Crystal Octahedra . . . . 704 D. G. Stepenshchikov The Leningrad Mining Institute Scientists Contribution to the Non-ferrous Metallurgy Ore Base Creation During the Second World War . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 711 V. V. Vedernikov Nesquehonite from the Kimberlite Pipe Obnazhennaya: Thermal Analysis and Infrared Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 717 N. V. Zayakina, S. S. Ugapeva, and O. B. Oleinikov New Data on the Crystal Chemistry of Technogenic Minerals from the Burned Dumps of Chelyabinsk Coal Basin . . . . . . . . . . . . . . . . . . . . . . 727 A. A. Zolotarev Jr., S. V. Krivovichev, M. S. Avdontceva, M. G. Krzhizhanovskaya, E. S. Zhitova, T. L. Panikorovskii, V. V. Gurzhiy, and M. A. Rassomakhin Author Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 735

Fundamental Issues of Mineralogy, Mineral Diversity and Evolution of Mineral Formation

Priorities of Modern Mineralogy A. M. Askhabov(B) Syktyvkar Branch of the Russian Mineralogical Society, IG FRC Komi SC UB RAS, Syktyvkar, Russia [email protected]

Abstract. This message continues traditions of Russian mineralogy, which has always paid special attention to general methodological discussion of the state and prospects for the development of mineralogical science. The author wrote the message on the occasion of the 25th anniversary of the publication of the programmatic article of Academician N. P. Yushkin “Priorities of mineralogy on the threshold of the 21st century” (Vestnik of the Institute of geology, Komi SC UB RAS, 1996, No. 5). We offer the author’s list of priority problems that are now attracting the most attention and from the solution of which breakthrough results are expected. These are mainly problems or research trends entrenched in the large mineralogical agenda in the last decade (“growth points”). This list is named the “mineralogical list” for brevity. It is compiled by analogy with the famous list of important and interesting physical problems by Academician V. L. Ginzburg. The “mineralogical list” as well as the “physical minimum” is addressed to young researchers and can be perceived as a minimal educational program for mineralogists. Keywords: Mineralogy · The most important problems of mineralogy · Mineralogical list · New ideas in mineralogy in the 21st century · Frontiers of mineralogical science

1 Introduction. About the Priority Problems of Mineralogy Extensive discussion of fundamental problems, ideas, the structure of mineralogy itself, relationships with other sciences are widespread among the mineralogical community. Moreover, in mineralogy this happens even more often in mineralogy than in other sciences. This is especially typical for Russian mineralogy, which is reflected in textbooks (Bulakh 1999) and analytical papers (Borutskiy 2007; Grigoriev 1990). In Russia, even special training courses were made (Koschug and Eremin 2015). Yu. B. Marin recently published a generalizing paper on the methodological principles of mineralogy, on the transition of mineralogical research to a qualitatively new level, and on the application of mineralogical information to solve fundamental problems of mineralogy. However, sometimes, in addition to analyzing the most important areas of mineralogical science, questions are also raised about whether mineralogy exists at all as an independent science with its own objects and methods. Even such a thesis was expressed about mineralogy as a part of the chemistry of inorganic compounds formed in nature (Bokiy 1997). In a © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 3–8, 2023. https://doi.org/10.1007/978-3-031-23390-6_1

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A. M. Askhabov

number of his works (Grigoriev Yushkin 1988; Yushkin 1988, 1996, 2002; Yushkin and Kuznetsov 2008), Academician N. P. Yushkin discussed general issues of mineralogy, problems and prospects of its development. Moreover, a quarter of a century ago, N. P. Yushkin published a list of mineralogy priorities (Yushkin 1996), according to which, in his opinion, the development of mineralogy will take place in the twenty-first century. Yushkin’s list included the following ten items: 1.

Development of a new “real” crystal chemistry of minerals based on high-resolution methods of electron microscopy to observe individual crystal-forming particles (molecules and atoms). 2. Studies of dispersed and ultradispersed states of matter. 3. Analysis of atomic-molecular and supramolecular structures, structural studies of protoindividuals. 4. Problems of syngenesis, interaction and co-evolution of the living and mineral worlds. Clarification of the role of minerals in the origin and maintenance of life, the role of organisms in the process of mineral formation and ore formation. 5. Geotechnogenesis and technical mineral formation. 6. Study of minerals as genetic indicators, as letters from the geological past. 7. Development of a scientific system of applied mineralogy, including topomineralogical study of ore-bearing regions, mineralogical forecasting, prospecting and evaluation and technological mineralogy. 8. Development of regional mineralogical research, creation of regional mineralogical generalizations. 9. Creation of a national machine database on minerals. 10. Creation of a methodological apparatus for solving a wide range of geological problems based on mineralogical data. At the same time, N. P. Yushkin noted that “these main directions do not, of course, determine the entire front of mineralogy development, but trace the main research impacts that ensure a breakthrough into the future” (p. 4). On the one hand, this list indicated directions that are really important for mineralogy, which are still relevant to this day. On the other hand, over the past years, dramatic changes have occurred in mineralogy, primarily due to the penetration into the nanoworld and borderline areas of knowledge, the emergence of new ideas and research methods. This prompted us to compile a certain list of priority problems that characterize the state of mineralogical science today. The list is named the “Mineralogical list” for brevity, and includes 17 items.

2 Priority Issues in Mineralogical Science (“Mineralogical List”) 1. 2. 3.

Discovery of new minerals. Forecast and design of mineral structures. Mineralogy of mantle and core.

Priorities of Modern Mineralogy

4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.

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Mineral formations at the ocean bottom. Mineral phases in extreme conditions. Minerals as promising materials. Surface of minerals. Two-dimensional mineral phases. Protominerals and protomineral state of matter. Non-classical mechanisms of mineral formation. Dispersed and nanostructured mineral substance. Mineral nanostructures and nanoindividuals. Organic minerals and organomineral formations. Minerals in biological systems. Evolution, irreversibility and self-organization in mineral systems. Complexity, modularity and hierarchy of mineral structures. New tools and objects of mineralogical research. Digital mineralogy. Big data and artificial intelligence in mineralogy.

3 Comments and Remarks on the “Mineralogical List” Before proceeding to some necessary comments and remarks on the list, we quote the words of Academician V. L. Ginzburg, that he accompanied his famous “list of important and interesting problems of physics and astrophysics” (“physical minimum”) (Ginzburg 2004). “Any such list cannot but be subjective. It is also clear that the “list” must change over time. It is clear, finally, that all the questions not included in the “list” can in no way be considered unimportant or uninteresting… Those who know important and interesting things that are beyond the “list” have no reason to be offended and should only supplement or change the “list"” (p. 1253). The “Mineralogical list” mainly includes problems or areas of research that have become entrenched in the large mineralogical agenda in recent decades. These are relatively new problems (“growth points”). They are mostly directed towards the future of mineralogy as a fundamental science. Mineralogy appears in this list as part of the vast science of mineral matter, developing in close cooperation with other related branches of natural sciences, primarily physics, chemistry and biology. It is this aspect (the fundamental nature of mineralogy) that is important here, and not that mineralogy is a geological science. Calls for the geologization of mineralogy change little in its modern appearance. A number of key positions in the list, as expected, are directly related to or repeat the directions from the Yushkin’s list of mineralogy priorities. The appearance or reformulation of some items in the list is related to the fact that the corresponding problems have recently come to the frontiers of mineralogical science and are attracting wide attention. For example, this refers to a new problem of analyzing the complexity of mineral systems, indicated in paragraph 15, alongside with the issue of modularity and hierarchy of mineralogical structures (Krivovichev et al. 2018). Certainly, I will not deny that the list includes problems to which the author is not indifferent or in the field of his own scientific interests. There is no particular need for detailed decifration and explanations of the content of the items briefly formulated in the list, in the preparation of their “passports”. It is clear that their content is broader than indicated in this or that paragraph. We will not

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forget about some conventionality of division into paragraphs and about their certain interdependence. Some points, perhaps, should have been combined, and some, on the contrary – divided. So paragraph 3 – “Mineralogy of mantle and core” – is unlikely to be disclosed without discussing issues related to the stability and prediction of the existence and behavior of minerals under conditions of high pressures and temperatures. The problem of deciphering the mechanisms of mineral formation, which is most urgent today and close to the author, turns out to be directly tied to the study of pre-nucleation clusters (quatarons) – new objects of the protomineral world – the world of creation of minerals (Askhabov 2019). Active theoretical and experimental research is underway on all the items indicated in the list. With some advance, the list includes items 16 and 17, in which mineralogy will inevitably be involved in the coming years. At the same time, in paragraph 16, we are talking more about completely new methods of mineralogical research, which, possibly, will be associated with the so-called megascience devices (new types of electron microscopes, synchrotrons, free electron lasers, etc.). New objects are today not minerals and not even materials of inorganic origin. So, quite recently, the objects of mineralogical studies are e.g. bone remains (Silaev et al. 2017). As for the first item on the list, the discovery of new minerals is and will be for a long time an exciting field of mineralogy, which ceases to be just an exciting field of competition for mineralogists, in a significant system influencing the prestige of science. The list, we have compiled, is not intended to embrace the immensity. In our opinion, it more sets some thematic landmarks and characterizes the current situation in mineralogical science. The “Mineralogical list” does not answer the question: what should be mineralogy, Yushkin’s priorities were aimed at that, but indicates the problems that most attract attention today, judging by the contents of magazines and conference programs. It is, as it were, the current “temporal” section of mineralogical science. It is easy to see that the list contains questions of varying degrees of elaboration and theoretical justification. But they are all, as they say, by ear and equally important and interesting, regardless of the order in the list. The addressees of the “mineralogical list” are mainly young researchers. They should have at least a general idea of the problems (directions) indicated in the list, and not only of the state of affairs in their narrow fields of science. This is, to some extent, the minimum educational program for mineralogists. In this sense, our list is close to the “physical minimum” of V. L. Ginzburg, which is also focused on educational goals. It is also necessary to pay special attention to the interdisciplinary nature of almost all the problems (topics, if you like) listed in the list. For example, points 2 and 3 play a key role in expanding our understanding in related areas of earth sciences, in understanding the composition and structure of deep geospheres. Items 5–8 deal with interdisciplinary issues at the intersection of mineralogy, chemistry, physics and materials science. It should be emphasized that a great material science potential is contained in clauses 6 and 7. Clauses 9 and 10 include issues on the border of mineralogy and biology (from the interaction between minerals and organic molecules, syngenesis and coevolution of living and mineral worlds to general issues of organic mineralogy and the role of organic matter and the processes of mineral and ore formation). The same points are directly related to the complex problem “mineralogy and life” formulated by N. P. Yushkin.

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4 About Possible Additions to the List The “Mineralogical list” should include a number of other areas that retain their relevance and importance, and have become integral parts of modern mineralogy. The extended list, in particular, could include problems of mineral diversity, mineralogy of ore deposits, genetic-informational mineralogy and typomorphism of minerals, experimental research in mineralogy and mineral synthesis. The latter may receive a “second breath” in connection with the development of a direction focused on obtaining new materials based on mineralogical information. An independent direction in mineralogical materials science can be the design and invention of potential minerals, the assembly of mineral structures by adding layers consisting of one or several layers of different minerals, thus obtaining peculiar mineral heterostructures and heterophase objects. This would be a significant advance for point 6. There is a sharp increase in interest in the problems of technological mineralogy and technogenesis of minerals, which is associated with their very important practical importance. Mineralogy of astroblemes, the study of meteorites does not lose its relevance. Research on space mineralogy (the Moon, planets, near-planetary dust complexes with a promising swing to solid exoplanets) is promised to revive. It would hardly be fair to leave the extended “Mineralogical list” without such classical sections as mineralogical crystallography and physics of minerals. At various mineralogical forums, it increasingly appears as a promising direction and medical mineralogy with the pharmaceutical industry on a mineral basis. These directions, despite their more traditional character, will be considered by many people to be even more important for progress in mineralogical science in general. It is clear that they will not go anywhere and the corresponding problems will be in the arsenal of modern mineralogy, it is possible that some of them will become super-priority at a certain stage.

5 Conclusion In conclusion, we note once again that the “Mineralogical list”, as well as all other similar lists, of course, can be continued, supplemented, changed. But all directions and interesting problems of mineralogical science cannot be covered. “Mineralogy in the entire space of this word” is broader and richer. Acknowledgments. This work was supported by the Russian Foundation for Basic Research (project 19–05-00460a).

References Askhabov, A.M.: Pre-nucleation clusters and nonclassical crystal formation. Zap. RMO, no. 6, pp.1–13 (2019) Bokiy, G.B.: Systematics of natural silicates. Results of Science and Technology. Ser. Crystal chemistry. M., vol. 31 (1997) Borutskiy, B.Ye.: Fundamental problems of ancient science. Nature (2), 5–14 (2007)

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Bulakh, A.G.: General mineralogy. St. Petersburg: SPbSU (1999). 354 p. Ginzburg, V.L.: What problems of physics and astrophysics now seem to be especially important and interesting. Phys. 103, 87 (1971) Ginzburg, V.L.: About superconductivity and superfluidity (what I succeeded and what failed), as well as the “physical minimum” at the beginning of the XXI century. UFN. 174(11), 1240–1255 (2004) Grigoriev, V.P.: Discourses on mineralogy. In: Proceedings of RMS. Ch. CXIX. Issue 1, pp. 3–12 (1990) Grigoriev, D.P., Yushkin, N.P.: New ideas and methods in genet icic mineralogy // New ideas in genetic mineralogy. Leningrad: Science, pp. 3–7 (1983) Koschug, D.G., Eremin, N.N.: Modern problems of mineralogy and crystallography. Training course, Moscow State University (2015) Marin, Y.: On mineralogical studies and the use of mineralogical information in solving the problems of petro- and ore genesis. Proc. RMS. 4, 1–15 (2020) Silaev, V.I., et al.: Ust-Poluyskoye Settlement-Sanctuary: experience of mineralogical and geochemical studies of human bone remains. Syktyvkar, Geonauka (2017). 64 p. Yushkin, N.P.: Mineralogy priorities on the threshold of the XXI century. In: Vestnik of the Institute of Geology, Komi Science Center, Ural Branch of the Russian Academy of Sciences, no. 5, pp. 2–4 (1996) Yushkin, N.P.: Problems and ways of development of mineralogical theory. Theory of mineralogy: Sat. scientific. Trudy, pp. 4–10 (1988) Yushkin, N.P.: Modern mineralogy and new trends in its development. In: Vestnik of the Institute of Geology of the Komi Scientific Center of the Ural Branch of the Russian Academy of Sciences, no. 7, pp. 17–19 (2002) Yushkin, N.P., Kuznetsov, S.K.: History, current state and prospects for the development of mineralogical research. In: Vestnik of the Institute of Geology of the Komi Scientific Center of the Ural Branch of the Russian Academy of Sciences, no. 12, pp. 12–16 (2008)

E. S. Fedorov’s “Drusites”: Metamorphic Reaction Structures in Paleoproterozoic Metagabbronorites of the Belomorian Province of the Fennoscandian Shield P. Ya. Azimov(B) Saint-Petersburg Branch of the Russian Mineralogical Society, Institute of Precambrian Geology and Geochronology, The Russian Academy of Sciences, St. Petersburg, Russia [email protected]

Abstract. The reaction structures (coronas) in metagabbronorites from the Belomorian Province were resulted from two stages of high-grade metamorphism. The early garnet-free coronas were formed at olivine/plagioclase boundary. They formed radial new-formed clinopyroxene and orthopyroxene grains after olivine with simultaneous replacement of magmatic plagioclase by metamorphic one + spinel. The early coronas were formed during low-pressure granulite metamorphism at 750–950 °C and 3–5 kbar. The late garnetiferrous coronas and peak mineral assemblage after olivine gabbronorites were formed during high-pressure high-temperature metamorphic event at 700–850 °C and 15–28 kbar. The retrograde high-pressure amphibolite metamorphism resulted in garnet-bearing and garnet-free antophyllite amphibolites after olivine gabbronorites. Keywords: Metabasites · Corona textures · Belomorian Province · Thermobarometry · TWEEQU

1 Introduction During him petrographic studies of the Karelian coast of the White Sea, famous crystallographer and petrographer E.S. Fedorov identified a group of basic igneous rocks and called them “drusites” (Fedorov 1896). Further studies showed that the group of “drusites” included several Paleoproterozoic plutonic mafic complexes with ages from 2.5 to 2.15 Ga (Stepanov and Stepanova 2010; Stepanova et al. 2022), intruding the supra- and intracrustal Archean metamorphic rocks of the Belomorian Province of the Fennoscandian Shield. The “drusite” textures (in modern terminology “corona textures”: Best, 2003) of these basites are reaction textures originated from metamorphic transformations of the Late Paleoproterozoic (~ 1.95–1.85 Ga) age (Alekseev et al. 1999; Stepanova et al. 2022). The prevailing group rocks among basic and ultrabasic rocks of the “drusite” complex rocks is the lherzolite-gabbronorite complex including quartz-free and olivine gabbronorites and plagiolerzolites with an age of 2.40–2.45 Ga (Stepanov and Stepanova 2010). The intensity of metamorphic transformations of these rocks is © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 9–16, 2023. https://doi.org/10.1007/978-3-031-23390-6_2

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not very great, so that relics of magmatic minerals were preserved. Metamorphic minerals, as a rule, are present as zonal reaction rims between grains of primary magmatic minerals. It is because of these structures that the rocks have been called “drusites”. The study of reaction structures in metabasites of the Belomorian Province allows us on the one hand to behold the process and mechanisms of transformations of igneous rocks into metamorphic ones, and on the other hand to determine the thermodynamic conditions of these transformations.

2 Geology and Petrography The Belomorian Province (BP) of the Fennoscandian Shield is composed of Mesoand Neoarchean supra- and intracrustal rocks (Hölttä et al. 2008). At the end of the Neoarchean (~2.7–2.6 Ga) it was reworked during the collision formed the Kenorland continent (Lubnina and Slabunov 2011). By the beginning of the Paleoproterozoic, the BP was part of the Archean craton. At the Early Paleoproterozoic, the BP was repeatedly intruded by continental mafic and ultramafic plutonic rocks of various compositions (Stepanova et al. 2022). The closure of the Lapland-Kola Ocean ~1.95–1.85 Ga ago led to a collision of continental masses, fragments of which are the modern Karelian and Murmansk Provinces of the Fennoscandian Shield. During this collision, BP rocks, including Paleoproterozoic intrusions, underwent high-grade metamorphism (Volodichev et al. 2012; Slabunov et al. 2016; Babarina et al. 2017; Li et al. 2017). A detailed study of the metamorphic transformations in gabbronorites was carried out for the rocks of two small gabbronorite massifs (Jokivarakka and Vuatvarakka) in the area of the Verkhnee Pulongskoye Lake in the central part of the Belomorian Province. The massifs are small boudinated fragments of intrusive bodies among aluminous and tonalitic gneisses of the Chupa Gneiss Belt (Babarina et al. 2017). Both massifs are composed of alternating olivine and olivine-free gabbronorites with magmatic parageneses Opx + Cpx + Pl + Ol ± Bt and Opx + Cpx + Pl ± Bt. The alternation of rocks is caused by primary magmatic layering. Gabbronorites were reworked during high-grade metamorphism. The strongest metamorphic transformations are manifested in the marginal parts of the massifs at the contacts with gneisses, where mafic rocks are converted into amphibolites without relics of magmatic structures. Most of the rocks in these massifs contain relics of magmatic minerals, and the degree of transformation varies from almost fresh rocks to rocks that are almost entirely composed of metamorphic minerals. The best-preserved relic mineral is magmatic orthopyroxene. In olivine gabbronorites reaction rims are formed between olivine and plagioclase. It is possible to distinguish two generations of such borders. The first generation is formed by zoned two-pyroxene coronas replacing olivine and contain no garnet (Fig. 1). Simultaneously alumina spinel and new-formed (metamorphic) plagioclase formed after magmatic plagioclase. The outer zone of two-pyroxene rims may contain spinel–clinopyroxene symplectites. Biotite with ilmenite inclusions is associated with these garnet-free rims. Sometimes pyroxene rims are overgrown with an outer zone composed of pale green pargasite. During further metamorphic transformations magmatic pyroxenes are replaced with an aggregate of metamorphic pyroxenes and fine-grained pargasite. The replacement began at the edges of the pyroxene grains and along the cleavage planes. Numerous

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submicroscopic ingrowths of alumina spinel in plagioclase led to brown colour of plagioclase in thin sections and blue or blue-green colour in samples. At the same time, magmatic plagioclase was replaced by more acidic metamorphic one. Relict grains of magmatic orthopyroxene contain brown submicroscopic chromite ingrowths, while clinopyroxene grains contain yellowish ingrowths of titanium minerals. The chromite ingrowths in orthopyroxene grains often emphasize growth zoning and sector zoning. Such ingrowths are a distinctive feature of relic magmatic pyroxene grains in the Belomorian metagabbronorites. In the pyroxene grains formed during metamorphism there are neither small ingrowths of chromite and titanium minerals nor a manifested zoning or sector zoning. The second generation of reaction rims in metagabbronorites consists mainly of garnet, sometimes with inclusions of pargasite hornblende and/or aluminous spinel. These rims formed at the pyroxene/plagioclase boundary. They also contain radial orthoand clinopyroxene grains after olivine. In some cases, garnet can contact with olivine without obvious signs of its replacement. In areas where garnet rims are manifested inclusions of ilmenite in biotite were transormed to rutile. Quartz in metamorphosed olivine gabbronorites is absent. The most complete metamorphic transformation of olivine gabbronorites led to the formation of pale-green or greenish-gray plagioclase-free orthopyroxene–anthophyllite– pargasite rocks (±garnet, ±magnesian biotite). For these rocks black coarse pyroxene grains are common. Usually, they are relics of magmatic grains. The garnet in these rocks is pale pink and rather magnesian. The molar part of the pyrope component in this garnet can reach up to 25%. Fine-grained anthophyllite and pargasite form fine intergrowths in the matrix. However, such fully transformed rocks are rare and tend to form thick veins or zones along fractures that were as fluid conduits. During the retrograde metamorphic stage garnets in these rocks were replaced by biotite-plagioclase symplectitic rims, amphiboles formed after orthopyroxenes. Finally, the rocks were transformed into garnet amphibolites and then into garnet-free amphibolites. In these amphibolites two amphiboles (anthophyllite and hornblende-pargasitic clinoamphibole) may coexist. In olivine-free gabbronorites two generations of reaction rims can also be distinguished. In the early rims magmatic orthopyroxene was replaced by metamorphic orthopyroxene with hornblende, whereas clinopyroxene was replaced by metamorphic metamorphic clinopyroxene or hornblende. The magmatic plagioclase was replaced by metamorphic plagioclase (without spinel), sometimes with amphibole ingrowths. Metamorphic biotite may contain ilmenite ingrowths. The second generation of garnet rims arose at plagioclase/orthopyroxene boundary. The garnet was in an assemblage with metamorphic orthopyroxene, clinopyroxene, and quartz. Rutile arose in biotite, whereas plagioclase disappeared. During intense metamorphic transormation mineral assemblage Opx + Cpx + Grt + Qtz ± Hbl ± Bt (without olivine) formed after olivine-free gabbronorite.

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Fig. 1. Garnet-free two-pyroxene rims after olivine and clouded plagioclase with spinel ingrowths in metagabbronorite from Jokivarakka olivine gabbronorite massif.

3 Thermobarometry Since complete equilibrium in rocks with reaction structures is practically not achieved, the most difficult problem for thermobarometry is the identification of equilibrium mineral asseblages and equilibrium compositions. The equilibrium degree varies greatly not only within one thin section, but also in the vicinity of one grain. Therefore, the use of classical thermobarometry in rocks with reactive structures is very difficult. To determine the PT–conditions of metamorphism the TWEEQU multi-equilibrium thermobarometry technique based on the identification of local equilibria between minerals (Berman 1991) was used. The calculations were performed using the WinTWQ program (Berman 2007) with the internally-consistent thermodynamic dataset JUN92 (Berman 1988) and BA96a (Berman and Aranovich, 1996; Aranovich and Berman 1996). To calculate and analyze the results we also used free add-ons for the TWQ program: TWQ_Comb (Dolivo-Dobrovolsky, 2006a) and TWQ_View (Dolivo-Dobrovolsky 2006b). Calculations of the PT–conditions of early rim formation in olivine gabbronorites were carried out using the mineral association Ol + Pl + Cpx + Opx with three independent reactions (IR): (1) Fo + 2 Hd = Fa + 2 Di, (2) En + 2 Hd = Fs + 2 Di, (3) 2 An + 2 Fo = En + 2 Di + aOpx (Al2 O3 ), while late rims using the mineral association Opx + Cpx + Grt ± Bt with 4 independent reactions (5 or 6 independent reactions in the presence of biotite): (4) Alm + 3 En = Prp + 3 Fs, (5) Alm + 3 Hd = Grs + 3 Fs, (6) En + 2 Hd = Fs + 2 Di, (7) 2 Prp = 3 En + aOpx, (8) Alm + Phl = Prp + Ann. Calculations were also carried out for rocks with peak mineral assemblage. For this case the mineral relations in the system can be described by 3 independent reactions: (4), (7) and (8). Calculations have shown that gabbronorites of Jokivarakka and Vuatvarakka massifs underwent two stages of metamorphic transformations. Early metamorphic coronas were formed under conditions of low-pressure granulite facies (750–950 °C and 3–5 kbar, Fig. 2). Later coronas and garnet-bearing mineral asseblages were resulted from high pressure – high temperature metamorphism (700–850 °C and 15–28 kbar, Fig. 3).

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Fig. 2. TWQ-diagram for garnet-free two-pyroxene corona after olivine in metagabbronorite from Vuatvarakka olivine gabbronorite massif; 3 IR (independent reactions).

Fig. 3. TWQ-diagrams for garnet-bearing reaction rims in metagabbronorite from Vuatvarakka olivine gabbronorite massif: (a) Grt–Opx–Bt assemblage, 4 IR; (b) Grt–Opx–Cpx assemblage, 3 IR.

4 Discussion The revealed sequence of rims is in good agreement with experiments on subsolidus equilibria in basic-ultrabasic rocks (Kushiro and Yoder 1966; Borghini et al. 2011). The melt crystallized at low pressures (under the conditions of the upper crust). As a result, the Ol+Pl assemblage was stable in the crystallized rocks. When an early (low pressure) granulite event is superimposed on igneous rocks, unstability of the olivine-plagioclase

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assemblage resulted in the crystallization of the Opx+Cpx+Pl+Spl metamorphic assemblage. The newly formed plagioclase together with spinel replaced the original (magmatic) one, and the clinopyroxene-orthopyroxene coronas replaced olivine. Thus, early rims are formed due to the reaction Ol + Pl1 → Opx + Cpx + Pl2 + Spl. Metamorphic plagioclase (Pl2 ) is more acidic than magmatic (Pl1 ), since the formation of aluminous spinel and clinopyroxene happened due to the decomposition of the anorthitic plagioclase component. The incomplete course of the reactions led to incomplete replacement of the original metamorphic minerals, despite the high temperatures. This incompleteness is primarily determined by the small amount of fluid in the system. The second metamorphic event occured under high pressure conditions, in which spinel together with pyroxene becomes unstable, as well as Opx+Pl mineral assemblage. Due to this unstability garnet was formed. In highly magnesian rocks, such as olivine gabbronorites and plagiolerzolites, plagioclase was consumed in the reaction faster than orthopyroxene. It led to the formation of the Grt+Opx assemblage. Na and Ca in the rock were redistributed into pargasite. The presence of amphibole indicates the participation of the fluid in metamorphic transformations. However, in the second (high-pressure) metamorphic event the lack of fluid also led to incompleted reactions. Both high-temperature metamorphic episodes (low-pressure and high-pressure) were related to the evolution of the Lapland-Kola orogen in the Late Paleoproterozoic (Daly et al. 2006; Slabunov et al., 2016; Babarina et al., 2017). The high-pressure event corresponded to the conditions of the continent–continent collision. The subsequent transformation of gabbronorites into amphibolites observed in the marginal parts of these and other massifs was resulted from the retrograde metamorphic processes during late stages of the same Lapland-Kola orogeny.

5 Conclusions 1. The reaction structures (coronas) in metagabbronorites from the Belomorian Province were resulted from two event of high-grade metamorphism which differ in pressure. 2. First event was low-pressure granulite metamorphism (750–950 °C and 3–5 kbar). 3. Second event was high-pressure high-temperature metamorphism (700–850 °C and 15–28 kbar) at its peak.

Acknowledgments. This study was carried out under government-financed research project FMUW-2022-0002 for the Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences.

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Stepanova, A.V., Stepanov, V.S., Larionov, A.N., et al.: Relicts of Paleoproterozoic LIPs in the Belomorian Province, eastern Fennoscandian Shield: barcode reconstruction for a deeply eroded collisional orogen. Geol. Soc. Lond. Spec. Pub. 518, 101–128 (2022). https://doi.org/ 10.1144/SP518-2021-30 Volodichev, O.I., Slabunov, A.I., Sibelev, O.S., Skublov, S.G., Kuzenko, T.I.: Geochronology, mineral inclusions, and geochemistry of zircons in eclogitized gabbronorites in the Gridino area Belomorian province. Geochem. Intl. 50(8), 657–670 (2012). https://doi.org/10.1134/S00 16702912060080 Yegorova, S.V., Stepanova, A.V.: Palaeoproterozoic gabbronorites in the north of the Belomorian mobile belt – New data on the mineral composition and chemistry. Trans. KarRC RAS. 3, 56–64 (2012). (in Russian)

Calcium and Cuprum Oxalates in Biofilms on the Surface of the Scoria Cones of Tolbachik Volcano I. A. Chernyshova(B) , O. S. Vereshchagin, M. S. Zelenskaya, D. Yu. Vlasov, O. V. Frank-Kamenetskaya, and D. E. Himelbrant Saint-Petersburg Branch of the Russian Mineralogical Society, Saint-Petersburg State University, Saint Petersburg, Russia [email protected]

Abstract. The study of biofilm oxalates creates the scientific basis for the development of modern nature-like biotechnologies in various fields of science and technology. Calcium (whewellite and weddellite) and copper (moolooite) oxalates in lichen thalli on scoria cones of Tolbachik volcano (Kamchatka Peninsula, Russia) were firstly found. The morphology of oxalate crystal has been described. New species of lichens (Psylolechia leprosa, Sarcogyne hypophaea, Rinodina gennarii, Ochrolechia subplicans) producing oxalic acid, which leads to the formation of oxalates, have been discovered. It was concluded, that in the process of biomineralization the growth of oxalate crystals alternates with their dissolution. Keywords: Microbe biomineralization · Scoria cones of volcano Tolbachik · Oxalate crystallization · Whewellite · Weddellite · Moolooite

1 Introduction In recent years, the world scientific community has shown significant interest in the mechanisms of biomineralization with the participation of microorganisms, which is associated with the study of modern mineral formation at the nano- and microlevels, as well as processes and phenomena occurring at the border of living and nonliving. These fundamental results create the scientific basis for the development of modern nature-like biotechnologies in various fields of science and technology. Crystallization of oxalates under action of microorganisms (bacteria, microfungi, microalgae, lichens) can take place on the surface of different rocks and minerals: carbonates, phosphates, oxides, silicates and others (e.g., Gehrmann and Krumbein 1994; Purvis et al. 2008). Only five oxalate minerals were found in biofilms with a predominance of lichens on the surface of rocks and minerals. Calcium oxalates monohydrate whewellite and dihydrate weddellite are the most common biofilm minerals. Previously, they were found on the surface of different calcium-containing rocks: carbonates (marble, limestone, dolomite), silicates (granite, serpentinite, gabbro, basalt, diabase, sandstone) and apatitenepheline ore (e.g. Adamo et al. 1993; Ascaso et al. 1982; Bjelland et al. 2002; Bungartz © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 17–24, 2023. https://doi.org/10.1007/978-3-031-23390-6_3

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et al. 2004; Gehrmann and Krumbein 1994; Jones et al. 1980; Marques et al. 2016; Prieto et al. 1997; Ríos de los et al. 2009; Rusakov et al. 2010; Souza-Egipsy et al. 2002; Syers et al. 1967; Wilson et al. 1981). Monohydrate copper oxalate moolooite was previously found in lichen thalli of Lecanora polytropa, Lecidea lactea, Lecidea inops, Acarospora rugulosa on copper and iron sulfides (chalcopyrite, pyrite) and weathering products (attackamite, brochantite) in basaltic lavas and more siliceous volcanic rocks (Chisholm et al. 1987; Purvis 1984; Purvis et al. 2008). Dihydrate magnesium oxalate glushinskite was discovered in lichens on Mg-enriched rock (Wilson et al. Wilson et al. 1981, 1980) and manganese oxalate was found on Mn-rich rocks (Wilson and Jones 1984). This work is devoted to the first discovery of oxalates in lichens on scoria cones of volcano Tolbachik, Kamchatka Peninsula (Fig. 1).

Ostry Tolbachik Plosky Tolbachik

Second scoria cone

Fig. 1. Volcano Tolbachik and it’s scoria cones

Volcano Tolbachik is located in the southern part of the Klyuchevskaya group of volcanoes, at the northern end of the Kuril-Kamchatka volcanic belt, near the intersection of the Kuril–Kamchatka and Aleutian Island arcs (Fedotov 1984). Tolbachik consists of three main parts: two cones Ostry Tolbachik and Plosky Tolbachik and Tolbachinsky Dol – lava-pyroclastic plain adjacent to the southern slopes of Plosky Tolbachik. Ostry and Plosky Tolbachik began to form about 7–10 thousand years ago (Churikova et al. 2013). The first large scoria cones were formed 2000–1500 years ago and composed mainly of magnesian basalts (for example, the Mountain 1004 scoria cone). Paleofumarolic fields of Mountain 1004 bears rich Cu and Pb mineralization including tenorite, anglesite, atacamite, antlerite, pyromorphite, etc. (Pekov et al. 2018b; Serafimova et al. 1994). The largest eruptions with the formation of scoria cones in recent years took place in 1975–1976 (the Great Tolbachik Fissure Eruption, GTFE) and 2012–2013 (Tolbachik

Calcium and Cuprum Oxalates in Biofilms on the Surface of the Scoria Cones

19

Fissure Eruption, TFE). They were predominantly basaltic, with two types distinguished - high-magnesian and high-alumina basalts. During the early eruption of 1975 (Northern Breakthrough, scoria cones I, II, III), pyroclastic ejections predominated, in composition corresponding to magnesian basalts. Their main minerals are olivine (Fo85–99 ), diopside, diopside-augite (Ca42–45 -Mg44–50 -Fe7–11 ) and plagioclase (An74 – An55 ). In the main stage of the eruption of 2012–2013 (e.g., scoria cone Naboko), basaltic lavas predominated (Volynets et al. 2013). Compositionally plagiogclase of Naboko vent lavas ranges from An70–72 to An80–80 , olivine (mainly found as microphenocrysts) ranges from Fo64 to Fo75 , clinopyroxene ranges from augite to salite (Volynets et al., 2015). Fumarole activity of GTFE and TFE continues until the present (e.g., Vergasova and Filatov 2012). The fumaroles of the scoria cones are characterized by a wide variety of minerals and mineral-forming elements. A great number of new minerals were discovered there (e.g., Pekov et al. 2018a; Siidra et al. 2017; Vergasova and Filatov 2012). Lichens are widespread on the Kamchatka Peninsula (Himelbrant et al. 2009, 2014; Khodosovtsev et al. 2004; Kukwa et al. 2014), which are among the first living organisms to grow on volcanic formations (Kukwa et al. 2014). The predominant group is crustose lichens (Himelbrant et al. 2009, 2014), which are well known for their ability to colonize stony substrates of various chemical compositions. Due to their active metabolism, they interact with bedrock minerals, which can lead to the oxalates formation (e.g., FrankKamenetskaya et al. 2019; Purvis et al. 2008; Rusakov et al. 2010).

2 Methods and Approaches Biofilms with a predominance of lichens were sampled during field work in the fall of 2019 from the scoria cones of Tolbachik Volcano. A total of 119 samples were collected: 43 samples from ancient scoria cone (Mountain 1004), 56 samples from scoria cones of 1975–1976 eruption (I, II and III scoria cones) and 20 samples from scoria cones of 2012–2013 eruption (Naboko scoria cone). The morphology, color and lichen/rock interface were studied using a Leica DM 2500P polarising light microscope. Lichen thalli and apothecia (spore-producing structure) were examined using a MZ16 Leica stereo microscope and Leica DM300 LED microscope. Lichen apothecia were studied by scanning electron microscopy (SEM). SEM studies of carbon-coated, unpolished samples were carried out by means of a HITACHI TM 3000. Thin sections of lichenized rock samples were observed by an optical microscopy Leica DM4500P and in SEM. Chemical composition of biominerals (both polished and unpolished samples) and underlying substrate (polished rock samples) were studied in carbon-coated samples by means of a Hitachi S-3400 N SEM equipped with an Oxford Instruments AzTec Energy X-Max 20 energy-dispersive X-ray (EDX) spectrometer, with the following parameters: 20 kV accelerating voltage, 1 nA beam current and 30 s datacollection time (excluding dead time). Only semi-quantitative analysis was obtained as most of the newly formed biominerals are H2 O-rich and form small crystals ( 2000 μg/g coupled to lower amounts of Cr ~ 900 μg/g

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can still be a characteristic of red prismatic crystals from the Khit-ostrov of Karelia. In contrast to them, Cr amounts > 800 μg/g with lower Fe values < 600 μg/g were also observed in pink prismatic corundum crystals from the Snezhnoe deposit in Tajikistan (Litvinenko et al. 2020, Sorokina 2021; Fig. 2). 3. The pink color and combinations of habit forms (dipyramidal, prismatic, or dipyramidal-prismatic) are in the borderline between two habit forms and colors. They associate with the amount of Cr from 500 to 1500 μg/g in corundum samples from Kenya (Sorokina et al. 2016a). Whereas, dipyramidal habit and the pink color were also found at similar Cr content as in case of Kenyan samples, however, also with Fe values at ca. 800 μg/g within sapphires from the Morogoro deposit in Tanzania (Fig. 2) 4. A rhombohedral shape and blue-violet color were observed at Cr < 500 μg/g and Fe > 2000 μg/g in Andranondambo sapphires from Madagascar (Sorokina et al. 2016a). 5. The pinacoidal habit was characteristic of zoned brown-blue corundums from the Ilmen Mountains with content of Fe > 1800 μg/g (Sorokina et al. 2016b, 2021). As it is shown above, the trace element composition of corundum influences significantly on its habit. This is linked to differences in the adsorption of specific trace-elements by the crystal faces during mineral growth (Sorokina, 2021). Table 1 demonstrates unit cell parameters for minerals, which are isostructural to corundum – members in the series Al2 O3 - Cr2 O3 (eskolaite) and Al2 O3 - Fe2 O3 (hematite). The c parameter in the unit cell of eskolaite increases comparing to this in corundum, however, the a/c ratio remains almost the same. Thus, Cr ions exceeding Al ions, when entering the crystalline structure of corundum, elongate it along the c axis (Fig. 2). This agrees with the experimental data: entering of Cr into corundum during its synthesis leads to the crystal growth elongated along the c axis (Hurlbut & Klein, 1985). Table 1. Cell parameters of corundum, and isostructural eskolaite, hematite, and ilmenite (www. mindat.org) Mineral

a, Å

c, Å

a:c

Corundum Al2 O3

4,75

12,98

1: 2,733

Eskolaite Cr2 O3

4,95

13,58

1: 2,743

Hematite Fe2 O3

5,04

13,77

1: 2,274

Ilmenite Fe2+ Ti4+ O3

5,09

14,09

1: 2,769

The higher values of Fe comparing to Cr (3: 1 and more), linked to the change in the surface energy. As a consequence, it increases both the c and a parameter of the corundum unit cell (see hematite, Table 1) coupled to almost constant a/c ratio. Surescu et al. (2010) presented the results of X-ray diffraction study of nanocomposite materials isostructural to corundum with the chemical formula xCr2 O3 - (1-x) α-Fe2 O3 , where x varies from 0.0 to 1.0. Thus, with decreasing of Cr molar amount from 1.0 to 0.4, both

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unit cell parameters (a and c) of the studied nanoparticles gradually increase (from 4.95 to 5.04 for parameter a and from 13.58 to 13.77 for parameter c). This is consistent with the obtained analytical data: co-introduction of Cr and Fe values (500 - 700 μg/g) leads to the fastest growth of corundum crystals along the c axis and perpendicular to it. Thus, in this case, the most rapidly growing faces will be the faces of dipyramid ω (14 14 28 3) (Fig. 2). The color of blue corundum varieties from the Ilmen Mountains is mainly associated with Fe3+ ions (Sorokina et al. 2017), which described above. Therefore, coloration by the charge transfer substitution 2Al3+ → Fe2+ + Ti4+ was not considered in the paper. However, for those varieties of blue corundum, where Ti4+ ions affect the color, it is possible to assume when entering the structure, they significantly change it. Thus, the unit cell parameters, as well as their ratio, significantly increase in isostructural ilmenite comparing to those in corundum. During the decreasing of the crystallization temperature, the Ti ions previously included into corundum structure most likely rejected by it, which, as a consequence, linked to frequent presence of ilmenite (and other minerals – Ti-oxides) in the form of exsolved solid inclusions. Titanium content in corundum structure is extremely low and likely does not significantly affect its morphology. Thus, the variation of corundum morphology is associated with a different Cr and Fe values, which dominated during crystal growth. Acknowledgments. Prof. Dr. L.N. Kogarko and colleagues from GEOKHI RAS, as well as prof. R.E. Botcharnikov, prof. W. Hofmeister, Dr. T. Häger and colleagues from JGU for their assistance in analytical studies and discussion of the results. The work was supported by a postdoctoral fellowship of Alexander von Humboldt Foundation and GEOKHI RAS.

References Häger, T., Dung, P.T.: Quantitative Fluoreszenz-Spektroskopie an natürlichen und synthetischen Rubinen. Berichte der Deutschen Mineralogischen Gesellschaft. Beihefte zum European Journal of Mineralogy. V. 12, N 1, p. 72 (2000) (in German) Hurlbut, C.S., Klein, C.: Manual of Mineralogy (20th ed.). Wiley, pp. 300–302 (1985). Internet Web-site www.mindat.org Litvinenko, A.K., et al.: Petrogenesis of the Snezhnoe Ruby Deposit, Central Pamir. Minerals 10(5), 478 (2020) Pauling, L., Hendricks, S.B.: The crystal structures of hematite and corundum. J. Am. Chem. Soc. 47, 781–790 (1925) Sorescu, M., Diamandescu, L., Tarabasanu-Mihaila, D., Krupa, S., Feder, M.: Iron and chromium mixed-oxide nanocomposites. Hyperfine Interact. 196, 359–368 (2010) Sorokina, E.S. Ontogeny and Quality of Gem Ruby from the Deposits of Central and SouthEast Asia. Unpublished Ph.D. Thesis, Fedorovsky All-Russian Research Institute of Mineral Resources, Moscow, Russia, 2011 (in Russian) Sorokina, E.S.: Relations Between Morphology of Corundum and Trace Element Composition. Zapiski RMO 150(3), 145–153 (2021) Sorokina, E.S., et al.: Sapphire-bearing magmatic rocks trace the boundary between paleocontinents: A case study of Ilmenogorsky alkaline complex, Uralian collision zone of Russia. Gondwana Res. 92, 239–252 (2021)

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Sorokina, E.S., Hofmeister, W., Häger, T., Mertz-Kraus, R., Buhre, S., Saul, J.M.: Morphological and chemical evolution of corundum (ruby and sapphire): crystal ontogeny reconstructed by EMPA, LA-ICP-MS, and Cr3+ Raman mapping. Am. Mineral. 101, 2716–2722 (2016a) Sorokina, E.S., Karampelas, S., Nishanbaev, T.P., Nikandrov, S.N., Semiannikov, B.S.: Sapphire Megacrysts in Syenite Pegmatites from the Ilmen Mountains, South Urals, Russia: New Mineralogical Data. Can. Mineral. 55, 823–843 (2017) Sorokina, E.S., Koivula, J.I., Muyal, J., Karampelas, S., Nishanbaev, T., Nikandrov, S.N.: Multiphase fluid inclusions in blue sapphires from the Ilmen Mountains, southern Urals. Gems Gemol. 52(2), 209–211 (2016b)

Hydrothermal Tourmaline from the Girvas Paleovolcano (Onega basin, Karelian Craton): Morphology and Chemical Composition E. N. Svetova(B) and S. A. Svetov Karelian Branch of the Russian Mineralogical Society, Institute of Geology, Karelian Research Centre of RAS, Petrozavodsk, Russia [email protected]

Abstract. The paper considers a previously unstudied hydrothermal tourmaline from the Paleoproterozoic basalts of the Girvas paleovolcano (Onega basin, Karelian Craton). Tourmaline in association with quartz and carbonate forms large nests in lavas, as well as nested and disseminated mineralization in the contact zones between lava flows and the eruptive center. Three morphological types of black-brown tourmalines were identified: large (up to 20 cm) prismatic crystals in quartz veins; fine-needle tourmaline crystals in nest-shaped clusters in association with quartz, albite, epidote, chlorite, and sulfides; radiated aggregates of fine-needle crystals on sub-vertical planes of tectonic dislocations of basalts − «tourmaline suns». According to their chemical composition tourmalines belongs to the alkaline series and corresponds to the isomorphic schorl-dravite group. Under electron microscope in cross-sections of tourmaline, needles zoning was revealed. Microscopic zoning is consistent with the chemical variation of Fe, Mg, Al, Na and vacancy content in individual zones. The zoning of tourmaline crystals provide evidence for multi-stage process of their formation, which proceeded during several impulses of hydrothermal activity, differing in the physicochemical parameters of the mineral formation environment. Keywords: Hydrothermal tourmaline · Crystal chemistry · Zoning · Paleoproterozoic basalts

1 Introduction Minerals of the tourmaline-supergroup are the widespread borosilicate minerals within the Earth’s crust with general formula XY3 Z6 [T6 O18 ][BO3 ]3 V3 W, where X — Na+ , Ca2+ , K+ , • (vacancy); Y — Mg2+ , Fe2+ , Mn2+ , Fe3+ , Al3+ , Li+ , Cr3+ , Ti4+ , Z — Al3+ , Mg2+ , Fe3+ , V3+ , Cr3+ ; T—Si4+ , Al3+ , B3+ ; B—B3+ ; V, W –OH, F, O (Henry et al. 2011). Tourmalines are formed in magmatic, metamorphic, hydrothermal associations in different P–T conditions, and its composition reflects the condition of mineral formation (Dutrov, Henry 2011). The Girvas paleovolcano is a relic of a volcanic complex associated with the activity of Paleoproterozoic (Jatulian) basaltic volcanism within the Onega basin (Fig. 1A, B) © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 103–109, 2023. https://doi.org/10.1007/978-3-031-23390-6_14

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(Svetov, Golubev 1967; Glushanin et al. 2011; Melezhik et al. 2013; Field guidebook…, 2015). In the conditions of modern erosion level, Girvas paleovolcano is only partially exposed. The paleovolcano structure involves: The volcanic cone section is represented by interbedded lava flows series in a 10– 15 m thick. In the lower part of the section, there are massive basalt lavas with brecciated top lava zones. Above there are brecciated lava-flows with a number of fragments of basalts and basaltic porphyrites. The fragments (2–15 cm in size) have an angular shape and a zonal structure. In the middle part of the section lavas are composed of hardblocked (0.5–1.2 m) breccia with lava matrix. In the upper part of the section, lavas are hydrothermally altered to talc-chlorite rocks due to fumarole activity. Some lava flows of this level have flow banding—pahoe-hoe. Contacts between flows are laterally observed. Zones of intense tourmalinization are detected among the system of fissures within the entire lava flows. A fragment of an eruptive neck 50 m in diameter breaks through the lava strata. The neck is composed of explosive hard-blocked lava breccia (basalts and porphyrites). The fragments are tightly packed, the matrix consists of crushed lava material. Eruptive neck breccia has sharp boundaries with the rocks of the lava cone. Tourmalinization and albite-quartz vein mineralization are partially present in the contact zones. In addition, the lava is broken through by a subcircular in plan explosion tube 10 × 30 m in size. The rock of the explosion tube is mainly represented by fine blocked eruptive breccia of basalts and basaltic porphyrites. The main part of the paleovolcano is overline by a thick cover of loose lacustrinealluvial Quaternary rocks. Previously at the studied object hydrothermal processes causing chemical remagnetization of the volcanic rocks were investigated (Buchkov et al., 2019). But a detailed study of tourmaline mineralization has not been carried out. The paper for the first to provide information on chemical composition, morphology and revealed zoning of hydrothermal tourmaline from basalts of the Girvas paleovolcano.

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105

Fig. 1. A – Location (A) and scheme of the geological structure (B) of the Girvas paleovolcano. 1 – quaternary rocks; 2 – eruptive breccia of explosion tube; 3 – eruptive neck breccia; 4 – fine blocked breccia; 5 – hard-blocked lava-breccia; 6 – fine-blocked lava-breccia; 7 – fumarole zones; 8 – massive basalts and basaltic porphyrites; 9 – fine-medium-grained gabbro-dolerites; 10 – tourmalinization zones; 11 – pyritization zones; 12 – albitization zones; 13 – lava flows direction; 14 – bedding elements of contact (a), sheet joint planes (b). Field outcrop photographs illustrating morphological types tourmalines: (C) – large tourmaline crystals in vein quartz; (D) – a nestshaped cluster of fine-needle tourmaline crystals; (E) – radiated aggregates of fine-needle crystals on sub-vertical plane of tectonic dislocations of basalts − «tourmaline suns».

2 Materials and Methods Tourmalines were sampled at the following localities of paleovolcano: a) contact zones between lava flows and the eruptive center; b) areas of tectonic dislocations of basalts in the upper part of the volcanic section. Within the studied outcrop the authors identified three morphological types of black-brown tourmalines: 1) large (up to 20 cm along the c axis) prismatic crystals in veins of milk-white quartz displaying graphic textures with quartz (Fig. 1C); 2) nest-shaped clusters of fine-needle tourmaline crystals (up to 5 cm along the c axis) in association with quartz, albite, epidote, chlorite and sulfides

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(Fig. 1D); 3) radiated aggregates of fine-needle crystals on sub-vertical planes of tectonic dislocations of basalts − «tourmaline suns» (Fig. 1E). The tourmalines were examined using VEGA II LSH (Tescan) scanning electron microscope (SEM) equipped with an energy dispersive analyzer INCA Energy 350 (W cathode, 20 kV accelerating voltage, 20 mA beam current, 2 μm beam diameter, counting time of 90 s) and X-ray powder diffractometer ARL X’TRA, Thermo Scientific (CuKαradiation, voltage 40 kV, current 30 mA). For SEM and microprobe investigations thin sections of tourmalines were coated with a thin carbon layer. Structural formulas of tourmaline were calculated by normalizing on 6 (apfu) of Si (Clark 2007).

3 Results and Discussion The results of microprobe analysis show that revealed morphological types of tourmaline differ slightly in chemical composition (Table). In according with nomenclature of the tourmaline-supergroup minerals (Henry et al. 2011), the all studied tourmalines belongs to alkali group and corresponds to isomorphic schorl-dravite series (Fig. 2). The species affiliation of the tourmaline samples to schorl-dravite series is also confirmed by the data of X-ray powder diffraction. The main differences in the chemical composition of large crystals from fine-needle crystals are in the higher Fe content and minor Mg content. Moreover, large tourmaline crystals are characterized by significant Ti concentrations, whereas fine-needle crystals have low Ti concentrations or do not contain Ti.

Fig. 2. Classification of tourmalines from basalts of the Girvas paleovolcano (Onega basin, Karelian Craton): (a) Ca − Na + K − Vac(X) ternary diagram showing the X-site occupancy; (b) binary diagram showing the a Mg/(Fe + Mg) versus Vac(X)/(Vac(X) + K + Na) ratios. 1 − large tourmaline crystals, 2 − fine-needle crystals.

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Table 1. Typical chemical composition of tourmaline samples (wt %) from basalts of Girvas paleovolcano (Onega basin, Karelian craton) Sample

T-2

T-1

T-3

Component

(n = 7)

#1

#3

#5

#6

#1_r

#6_l

#9_p

SiO2

34,92

36,34

36,17

35,7

35,54

36,27

34,54

35,99

TiO2

0,55

0

0

0

0

0

0

0

Al2 O3

29,28

26,88

26,75

27,7

27,13

28,33

24,31

29,41

FeO

13,04

11,65

11,61

10,59

9,85

10,58

14,51

7,73

MgO

3,11

7,54

7,4

7,52

7,49

7,09

6,79

7,72

CaO

0,44

0

0

0

0,35

0,97

0,89

0,36

Na2 O

2,23

2,76

2,59

2,57

2,42

2,4

2,31

2,8

Cymma

83,58

85,17

84,53

84,07

82,78

85,63

83,35

84,00

Normalization on 6 (apfu) Si Z Al

5,929

5,231

5,23

5,487

5,398

5,523

5,095

5,779

Z Fe3+

0

0,46

0,44

0,37

0,21

0

0

0

Z Mg

0,07

0,31

0,33

0,14

0,39

0,477

0,905

0,221

Cymma Z

6

6

6

6

6

6

6

6

Y Al

0

0

0

0

0

0

0

0

Y Ti

0,07

0

0

0

0

0

0

0

Y Fe2+

1,87

1,14

1,17

1,12

1,18

1,464

1,726

1,078

Y Mg

0,73

1,55

1,50

1,74

1,50

1,272

0,845

1,697

Cymma Y

2,67

2,70

2,67

2,86

2,67

2,736

2,57

2,775

X Ca

0

0

0,06

0,172

0,208

0,064

0,08

0

X Na

0,74

0,88

0,83

0,84

0,79

0,77

0,734

0,905

X Vac

0,18

0,12

0,17

0,16

0,15

0,058

0,058

0,031

Cymma X

1

1

1

1

1

1

1

1

V OH

3

3

3

3

3

3

3

3

W OH

0,50

0,58

0,50

0,70

0,53

0,677

0,512

0,744

WO

0,51

0,42

0,50

0,30

0,47

0,323

0,488

0,256

Cymma V + W

4

4

4

4

4

4

4

4

Mg/(Mg + Fe)

0.30

0.54

0.53

0.56

0.58

0.54

0.60

0.64

Vac/(Na + K + Vac)

0.19

0.12

0.17

0.16

0.15

0.07

0.068

0.033

T-2 – large prysmatic tourmaline crystals, T-1 – fine-needle zonal crystal from nest (Fig. 3a), T-3 – fine-needle zonal crystal from nest (Fig. 3b), n = number of individual analytical points used in the average.

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Under electron microscope in cross sections of tourmaline needles reveal two characteristic zoning types. The first type is concentric with distinct boundaries between the central (axial), intermediate and marginal zones (Fig. 3A). According to microprobe profiling, microscopic zoning is consistent with the chemical composition of the identified zones. The tourmaline crystal is dravite, its central part is characterized by a higher Fe, Na content and a lower Mg content relative to the rim zone. The interconnected behavior of the content of Fe, Mg, Al, Na and vacancy is established: the higher the content of Fe and Na, the lower the content of Al and vacancy; the higher content of Fe, the lower content of Mg. The second type combines «patchy zoning» (Streck 2008) of the central part of the crystal and a pronounced rim, which is also reflected in variations in the content of Fe and Mg (Fig. 3B). Based on the crystal-chemical calculations the main part of the crystal is schorl, the rim of the crystal is close to dravite, and «patches» in center correspond to dravite. This zoning pattern probably indicates that a crystal was in the process of re-equilibration through diffusion (Streck 2008).

Fig. 3. BSE images of zonal structure of cross sections of fine-needle tourmaline crystals from basalts of the Girvas paleovolcano: a – concentric zoning (T-1 in the Table); b – patchy zoning (T-3 in the Table).

The zoning of tourmaline crystals indicates that the process of their formation was discrete and proceeded for several pulses of hydrothermal activity, differing in the physico-chemical parameters of the mineral formation environment. Acknowledgements. The study was conducted as part of a state project accomplished by Institute of Geology of the Karelian Research Centre of the Russian Academy of Sciences.

References Bychkov, A.Y., Popova, Y.A., Kivadze, O.E., Lubnina, N.V.: A thermodynamic model of chemical remagnetization based on the example of the Girvas Paleovolcano in the onega structure of the Carelian Craton. Moscow Univ. Geol. Bull.74,154–161 (2019) Clark, K.M.: Tourmaline: structural formula calculations. Canadian Mineralogist. 45, 229−237 ( 2007)

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Dutrow, B.L., Henry, D.J.: Tourmaline: a geologic DVD. Elements. 7, 301–306 (2011) Field guidebook of XII all-Russian petrographic conference «Petrography of igneous and metamorphic rocks». Petrozavodsk: KRC RAS, p. 96 (2015). [In Russian] Glushanin, L.V., Sharov, N.V., Shchiptsov, V.V.: Paleoproterozoic Onega structure: geology, tectonics, structure, and metallogeny; karelian research centre, RAS: Petrozavodsk, Russia, p. 431 (2011). (In Russian) Henry, D.J., et al.: Nomenclature of the tourmaline-supergroup minerals. Am. Miner. 96, 895–913 (2011) Kulikov, V.S., et al.: Geological map of Southeastern Fennoscandia (scale 1:750,000): a new approach to map compilation. Trans. KarRC RAS. 2, 3–41 (2017). [In Russian] Melezhik, V.A., Medvedev, P.V., Svetov, S.A.: The Onega basin. In: Melezhik, V.A., et al. (eds.) Reading the Archive of Earth’s Oxygenation, pp. 387–490. Springer, Heidelberg, (2013). https:// doi.org/10.1007/978-3-642-29682-6_9 Streck, M.J.: Mineral textures and zoning as evidence for open system processes. Rev. Mineral. Geochemis. 69, 595–622 (2008) Svetov, A.P., Golubev, A.I.: A volcanic edifice–of the Jatulian volcanic complex (Central Karelia). Dokl. Akad. Nauk SSSR. 77(1), 164–167 (1967). [In Russian]

Ti-Fe-Nb Mineral Phases from the Boxiton Bearing Weather Bark of the Verkhne-Shchugorsky Deposit (Middle Timan) O. V. Udoratina1(B) , D. A. Varlamov2 , B. A. Makeev1 , V. P. Lutoev1 , and A. S. Shuyskiy1 1 Syktyvkar Branch of the Russian Mineralogical Society, Institute of Geology, FRC Komi SC

UB RAS, Syktyvkar, Russia [email protected] 2 Moscow Branch of the Russian Mineralogical Society, Institute of Experimental Mineralogy RAS, Chernogolovka, Russia

Abstract. In the bauxitebearing crust of weathering of the VerkhneShchugorskoye deposit (Middle Timan, Russia), developed over alkaline metasomatites, the presence of Ti-Fe-Nb phases unusual in composition (with high TiO2 contents up to 20–40 Wt%) was established. Ti-Fe-Nb phases are found in alkaline metasomatites and rocks of the bauxitebearing crust of weathering along them in aggregates with columbite in the form of nesting accumulations, veinlets and rare phenocrysts and are characterized by wide variations in chemical composition, significantly differing from the minerals of the Ti-Fe-Nb system described in the literature. Presumably, this is a new mineral species corresponding to the compositions of the (Ti, Nb) (Fe, Nb) O4 series, which is confirmed by preliminary data of single crystal diffractometry and Mossbauer spectroscopy. Keywords: Ferrocolumbite · Titanium-niobium phases · Crust of weathering · Middle Timan

1 Introduction This article is devoted to the discovery of mineral phases of unusual composition Ti-FeNb in bauxitebearing crusts of weathering (BCW) from alkaline metasomatites of the Timan Ridge. Ore rare-metal-rare-earth mineralization (Nb, Sr, LREE, Th) and zones of corresponding disseminated mineralization are developed in the rocks of the bauxite, phosphate-bauxite and rare-metal-bauxite subformations of the Verkhne-Shchugorskoe deposit (Middle Timan, Komi Republic, Russia; 64°24 N, 51°04 E). Ore rare-metalrare-earth areas are observed in bauxite-bearing weathering crusts based on alkaline metasomatites, which, in turn, were formed from terrigenous-sedimentary rocks of the Pavyug and Vorykva suites (Likhachev 1993). © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 110–116, 2023. https://doi.org/10.1007/978-3-031-23390-6_15

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On the Middle Timan, within the Chetlassky Kamen, rare-metal-rare-earth occurrences are widely developed, united in the Kosyusky ore cluster (Kosyuskoe, Novobobrovskoe, Verkhne-Bobrovskoe, Oktyabrskoe, Mezenskoe, Nizhne-Mezenskoe, Verkhne-Shchugorskoe). The bulk of ore rare-metal-rare-earth bodies and alkaline metasomatites (fenites) are developed in quartzite sandstones of the Chetlas Group (Svetlinskaya, Novobobrovskaya, Vizingskaya formations) and partially in terigenic-carbonate deposits of the Bystrinskaya series (Anyugskaya, Rochuk / Vorygitinskaya, Paunya, Pavunya. The main minerals concentrators of complex mineralization in various manifestations are represented by monazite, xenotime, columbite, pyrochlore. Rare metal-rare earth mineralization localized in the rocks of the vein complex and alkaline metasomatites (both sodium and potassium) is genetically associated with the plume Kosyu complex of ultrabasic rocks with carbonatites (Nedosekova et al. 2011, 2014, 2017). There is a point of view that the rocks belong to the FES (fluid-explosive structure) of the carbonatite-alkaline type of mantle nature of a very long formation (Golubeva et al. 2019). The age of sandstones of the Svetlinskaya Formation, which serves as a substrate for ore metasomatites, is now estimated as Late Riphean (U-Pb, LA ICP MS based on zircons from quartzite sandstones of the Novobobrovsky ore field (Udoratina et al. 2017), the age of the youngest zircon is 1100 Ma, a similar age was also obtained for the stratotypes of the Chetlas Suites. The age of the magmatic formations is estimated by the K-Ar and Ar-Ar (from phlogopite) methods at the level of 600 Ma (Udoratina, Travin, 2014]. There is a point of view that the age of the magmatic formations is older and is 820 ± 9 Ma. The age of mineralization processes, determined directly from the ore minerals of the Novobobrovsky occurrence (U-Th-Pb (from monazite), Sm-Nd (thoritecolumbite-monazite)), is 552 ± 31 Ma and 581 ± 47 Ma, respectively (Udoratina et al. 2015; 2016; Udoratina and Kapitanova, 2017). The age determined by the Ar-Ar method from the microcline of the Oktyabrskoye deposit is 513.2 ± 3.8 Ma (Udoratina et al. 2020). According to stock data ore-metasomatic processes at the Verkhne-Shchugorsk occurrence are dated at a level of 520 Ma (K-Ar). According to I.I.Golubeva et al., the processes of alkaline metasomatism and ore genesis may be more ancient based on the dating of albite from cement brecciated xenolith FES (Kosyu ore field), its age (Ar-Ar method) is 845 ± 8 Ma (Golubeva et al. 2019). Previously, V.V. Likhachev studied in detail similar Ti-Fe-Nb phases both in metasomatites (substrate rocks) and in BCW rocks: columbite (Fe-columbite) was examined and “iron niobate” was discovered (Likhachev 1993, p. 161) in the form of an independent phase and in a mixture with Fe-columbite. V.V. Likhachev assumed that during the oxidation of Fe2+ to Fe3+ , the columbite structure is retained only up to a certain concentration of Fe3+ ions, but the parameters of its crystal lattice decrease. The latter is due to the difference in the ionic radius of Fe2+ and Fe3+ . When a certain limit of Fe3+ concentration is reached, the structure of columbite changes with a transition to the structure of the wolframite type, which is characteristic of FeNbO4 . At the same time, V.V. Likhachev considered the processes of weathering as the main reasons for the formation of these phases. Weathering processes cause changes in the physical and chemical properties of columbite. Its crystals become fractured, porous, cavernous. Chemical changes in columbite (Likhachev 1993, p. 165) consist in the oxidation of its iron. In this case, the columbite structure is retained up to a certain concentration of Fe3+ ions, only the

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unit cell parameters associated with different radius of Fe2+ and Fe3+ change. Complete oxidation of iron in columbite leads to the formation of iron niobate, a compound corresponding to the formula FeNbO4 . Bauxite-bearing crusts of weathering of lateritic feldspar metasomatites inherit the main textural and structural features of primary-layered alkaline metasomatites and largely retain the ore mineralization of the latter (especially resistant to weathering). The rare-metal-rare-earth complex (Nb, Sr, LREE, Th) of minerals is also inherited from alkaline metasomatites and is represented by pyrochlores of various variations (pyrochlores proper, Sr-pyrochlores, Pb-pyrochlores), columbites (Fe-columbite, Ticolumbites), ilmenorutile REE phosphates (monazite, xenotime, more rare complex phosphates). The material under study is represented by monofractions of titanium-niobium phases isolated by the authors from bulk core samples from wells drilled during exploration at the Verkhne-Shchugorskoye bauxite deposit (Bauxite Timana OJSC), as well as from the collection of V.V. Likhachev (Institute of Geology, Federal Research Center of the Komi Ural Branch of the Russian Academy of Sciences, Syktyvkar), collected earlier on the basis of geological survey materials. The objective of the study was to identify primary and superimposed (secondary, metasomatic) mineral complexes of ore zones, to establish the mineral composition and genetic characteristics of mineral formation processes.

2 Research Methodology A comprehensive study of monofractions of columbites and similar Ti-Fe-Nb phases (with high contents of titanium and niobium) was carried out using the analytical equipment of the Geoscience Center for Shared Use “Geoscience” (Syktyvkar, Russia) and the Institute of Experimental Mineralogy (IEM RAS, Chernogolovka, Russia). Individual grains and aggregates were mounted in polished epoxy blocks, after which a detailed electron probe microanalysis was carried out, including the acquisition of images of the studied objects in secondary and back-scattered electrons, as well as local X-ray spectral microanalysis. The work was carried out on digital scanning electron microscopes manufactured by Tescan (Tescan Orsay Holding, Brno, Czech Republic, https://www. tescan.com): (1) Tescan Vega 3 LMH with an Oxford Instrument X-Max 50 mm2 energy dispersive attachment (IG Komi SC UB RAS) and (2) Tescan VEGA-II XMU with EDS INCA Energy 450 and WDS Oxford INCA Wave 700 (IEM RAS). The studies were carried out at an accelerating voltage of 20 kV. The current of absorbed electrons on the studied samples is from 150 to 400 picoamperes (depending on the microrelief, structure and composition of the sample). The size of the electron probe on the sample surface was 157–180 nm, with scanning up to 60 nm. The excitation region, depending on the composition of the sample and the geometry of the phases, can reach 5 µm in diameter. Standards - pure metals and synthetic oxides and silicates.

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In addition, after the discovery of unusual mineral phases, a preliminary study was carried out by X-ray diffraction (single crystal and powder diffractometry) methods (Apatity, KSC RAS, T.L. Panikorovsky) and Mossbauer spectroscopy (Chernogolovka, IEM RAS, Voronin M.V.), which confirmed the highly probable assignment of the studied Ti-Fe-Nb phases to new mineral species with the assumed formula (Ti, Nb) (Fe, Nb) O4 .

3 Results and Discussion of Results The studied aggregates and grains reach a size of a few millimeters and, according to microprobe studies, have a complex internal structure (Fig. 1, a-d), due to the intergrowth of columbites proper and high-titanium ferroniobium phases, which have no analogues described in the literature. The chemical composition of the phases varies over a wide range within grains (Table 1). Low-titanium columbites (the lightest phase, TiO2 content less than 5 Wt%, Nb2 O5 > 65 Wt%) form a complex “mosaic” aggregate with “titanium columbites” (an old term, previously described finds in Vishnevy Gory and Yenisei Ridge (Eskova et al. 1964)) with TiO2 contents 5–15 Wt%, Nb2 O5 57–62 Wt%). In terms of chemical composition, columbites are practically pure ferrocolumbites FeNb2 O6 , manganese differences are practically absent, as well as tantalum variations. Some of the compositions of highertitanium phases, previously characterized as “titano-columbites”, contain up to 15 Wt% TiO2 , and presumably develop in more alkaline media than columbites. The boundaries between the phases are distinct, but extremely whimsical. Less developed (in the form of separate spots, fragmentary zones, rims along the “titano-columbites”) phases with the composition range of TiO2 18–27 Wt%, Nb2 O5 47–55 Wt% (Dark gray phases in Fig. 1), and in a number of grains ultra-high-titanium varieties were found (edges, zones with sharp boundaries, for example, in Fig. 1a), where the titanium content rises to 38–43 Wt% and niobium drops to 38–42 Wt% Nb2 O5 . In this case, the iron contents are quite stable - 17–29 Wt% FeO and do not strongly depend on the Ti:Nb ratio (the calculation was made for ferrous iron, although according to the data of Mössbauer spectroscopy, Fe3+ , most likely, predominates in the composition of aggregates). As in columbites, there are practically no impurities of other elements (Mn, Ta), excluding vanadium (contents up to 4 Wt% V2 O3 , in low-titanium varieties the contents of titanium and vanadium are even comparable). In ultra-high-titanium variations, the titanium content can exceed (in AT%) the niobium content by almost two times.

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Fig. 1. Ti-Fe-Nb aggregates (a-d): light - ferro-columbites and “titano-columbites”, dark gray and dark - high- and ultra-high-titanium Fe-Nb phases. Dot numbers correspond to compositions in Table 1. (e) Flattened chemical composition diagram of Ti-Fe-Nb phases. Mnz - monazite, Bar - barite. 132949, 132950 - numbers of analyzed samples

In addition to the Ti-Fe-Nb phases, the aggregates contain small inclusions of barite, monazite, and xenotime; there are pyrite and complex-zonal phosphates Al + Sr + Pb + Fe (in the rims there are zonal spherulites up to 20 µm), similar in composition of Pb2 (Fe3+ ,Al) (PO4 ) (PO3 OH) (OH)2 and Plumbogummite PbAl3 (PO4 ) (PO3 OH) (OH)6 , as well as small unidentified Nb-U oxide phases in the cracks and in the rims of the aggregates. The Ti:Nb correlation coefficient (for atomic %) is very high and reaches −0.91, which indirectly indicates the substitution of niobium for titanium, while the Ti:Fe dependence is significantly weaker (−0.49), and Fe:Nb is practically absent (−0.09).

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The described phases generally occupy an intermediate position between rossovskite (Fe3+ ,Ta) (Nb,Ti)O4 (Konovalenko et al. 2015) and high-niobium ilmenorutiles (with Nb2 O5 contents up to 30, TiO2 up to 60, FeO up to 10 Wt%), but they are quite different from them in terms of composition and structural features. Table 1. Typical compositions of Ti-Fe-Nb oxide phases (Wt%). The numbers correspond to the numbers of the points in Fig. 1 a–d № № TiO2 fig o.b a

b

c

d

V2 O3

Cr2 O3

MnO FeO

Nb2 O5

Sum

Calculated formulas (for 6 oxygen atoms)

1

40.46 1.25

–

–

17.29 39.35

2

20.79 1.28

0.32

–

22.45 54.26

98.35 Ti1.43 V0.05 Fe0.68 Nb0.84 O6

3

9.90 0.89

–

–

27.12 62.33

100.24 Ti0.38 V0.04 Fe1.15 Nb1.43 O6

4

4.21 0.00

–

–

29.13 67.02

100.36 Ti0.16 Fe1.26 Nb1.57 O6

5

42.93 1.43

–

–

16.55 38.12

99.03 Ti1.5 V0.05 Fe0.64 Nb0.8 O6

1

12.62 0.78

–

–

25.54 60.46

99.40 Ti0.48 V0.03 Fe1.09 Nb1.39 O6

2

38.16 0.85

–

–

17.63 42.28

98.92 Ti1.36 V0.03 Fe0.69 Nb0.91 O6

3

22.46 0.93

–

–

21.13 53.51

98.03 Ti0.85 V0.04 Fe0.89 Nb1.22 O6

4

21.92 1.38

–

–

21.60 54.59

99.49 Ti0.82 V0.06 Fe0.9 Nb1.23 O6

1

12.56 0.95

–

–

26.37 59.35

99.23 Ti0.48 V0.04 Fe1.12 Nb1.36 O6

2

18.93 0.78

–

–

24.60 55.42

99.73 Ti0.71 V0.03 Fe1.02 Nb1.24 O6

3

4.55 0.62

–

–

29.23 65.94

100.34 Ti0.18 V0.02 Fe1.26 Nb1.53 O6

4

1.25 0.00

–

0.48

18.68 79.70

100.11 Ti0.05 Mn0.02 Fe0.88 Nb2.04 O6

1

11.56 0.78

–

–

25.54 61.39

99.27 Ti0.45 V0.03 Fe1.1 Nb1.42 O6

2

5.07 0.36

–

–

29.14 66.07

100.64 Ti0.19 V0.0 1Fe1.25 Nb1.54 O6

3

1.95 –

–

0.37

19.36 77.98

99.10 Ti0.78 V0.05 Cr0.01 Fe0.93 Nb1.22 O6

99.66 Ti0.08 Mn0.02 Fe0.91 Nb1.99 O6

Additional preliminary analytical studies (single crystal and powder diffractometry, Mossbauer spectroscopy, Raman spectroscopy) confirm the primary conclusions that these aggregates are variations of a new mineral species corresponding to the compositions of the series (Ti,Nb) (Fe,Nb)O4 with a structure corresponding to monoclinic system of space group P21 21 2. Confirmation of the discovery of a new mineral species requires more precise analytical studies, which are currently being carried out. Acknowledgments. This work was supported by the Russian Foundation for Basic Research and the Komi Republic (Grant No. 20-45-110-010, supervisor O.V. Udoratina).

References Golubeva, I.I., Remizov, D.N., Burtsev, I.N., Filippov, V.N., Shuisky, A.S.: Fluidizate-explosive ultramafic rocks of the Middle Timan dyke complex and their paragenetic relationship with carbonatites. Reg. Geol. Metallogeny. 80, 30–44 (2019)

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Eskova, E.M., Zhabin, A.G., Mukhitdinov, G.N.: Mineralogy and geochemistry of rare elements of the Cherry Mountains, p. 319. Nauka, Moscow (1964) Yu, P. I.: Magmatism of Timan and the Kanin Peninsula. M.-L .: Nauka, p. 126 (1964) Likhachev, V.V.: Rare-metal bauxite-bearing weathering crusts of the Middle Timan. Syktyvkar, publishing house of the Komi Scientific Center of the Ural Branch of the Russian Academy of Sciences. 1993.224 s Nedosekova, I.L., Vladykin, N.V., Udoratina, O.V., Ronkin, Y.: Carbonatites of the Chetlas complex (Middle Timan): geochemical and isotope data. EZHEGODNIK-2012, Tr. IGG UB RAS, 160, 150–158 (2013) Nedosekova, I.L., Zamyatin, D.V., Udoratina, O.V.: Ore specialization of carbonatite complexes of the Urals and Timan. Litosfera 2, 60–77 (2017) Nedosekova, I.L., Udoratina, O.V., Vladykin, N.V., Pribavkin, S.V., Gulyaeva, T.Y.: Petrochemistry and geochemistry of dike ultrabasites and carbonatites of the Chetlas complex (Middle Timan). Yearbook-2010, Tr. IGG UB RAS. 158, 122–130 (2011) Udoratina, O.V., Burtsev, I.N., Nikulova, N. Y., Khubanov, V.B.: Age of metasandstones of the Upper Precambrian Chetlas Group of the Middle Timan on the basis of U-Pb dating of detrital zircons // Bul. MOIP. Dept. geol. 5, 15–32 (2017) Udoratina, O.V., Viryus, A.A., Kozyreva, I.V., Shvetsova, I.V., Kapitanova, V.A.: Age of monazites of the vein series of the Chetlas complex (Middle Timan): Th-U-Pb data. Bulletin of the Institute of Geology of the Komi Scientific Center of the Ural Branch of the Russian Academy of Sciences. Syktyvkar 3, 23–29 (2015) Udoratina, O.V., Kazantseva, M.I., Savatenkov, V.M.: Sm-Nd dating of ore minerals of the Novobobrovskoe deposit (Middle Timan). Alkaline magmatism of the Earth and associated deposits of strategic metals. Tr. In: XXXIII International Conference Moscow. GEOCHI. 27 May 2016. Resp. ed. acad. Kogarko L. N. M.: GEOKHI RAN, pp. 134–136 (2016) Udoratina, O.V., Kapitanova, V.A.: Rare-metal-rare-earth deposits and ore occurrences in the north of the Urals and Timan: geochronology of the ore process. Izvestiya Komi Scientific Center Ural Branch of the Russian Academy of Sciences 4(28), 86–101 (2016) Udoratina, O.V., Travin, A.V., Burtsev, I.N., Kulikova, K.V., Gubarev, I.A.: Oktyabrskoe ore field (Middle Timan): Ar-Ar data. In: Proceedings of the Fersman Scientific Session of the Geological Institute KSC RAS 17, 534–538 (2020) Konovalenko, S.I., et al.: A new mineral species rossovskite, (Fe3+ , Ta) (Nb, Ti)O 4: crystal chemistry and physical properties. Phys. Chem. Miner. 42, 825–833 (2015). https://doi.org/10.1007/ s00269-015-0766-5 Udoratina, O.V., Travin, A.V.: Alkaline picrites Chetlassky complex Middle Timan: Ar-Ar data. “Ore potential of alkaline, kimberlite and carbonatite magmatism”. In: Materials of 30 International Conference. Antalya-Moscow, pp. 82–84 (2014)

Scandium Garnets from Chloritolites, South Ural D. A. Varlamov1(B) and V. V. Murzin2 1 Moscow Branch of the Russian Mineralogical Society, D.S. Korzhinskii Institute of

Experimental Mineralogy RAS, Chernogolovka, Russia [email protected] 2 Ural Branch of the Russian Mineralogical Society, The Zavaritsky Institute of Geology and Geochemistry of the Ural Branch (UB) of the Russian Academy of Sciences (RAS), Yekaterinburg, Russia Abstract. During studying chloritolites from copper ore occurrences near the Muldakaevo village (Uchalinsky district, Bashkortostan, Russia), very exotic scandium-vanadium garnets were identified, corresponding in composition to the series of eringaite - goldmanite - andradite. Previously, similar garnets (but represented by Sc-Zr varieties) were found only in rodingite-like rocks on the Vilyui River, Yakutia. The ore occurrences are located 35 km southeast of the city of Miass in the eastern foothills of the Southern Urals and are localized in metasomatites of the Late Devonian-Permian age. Keywords: Eringaite · Goldmanite · Chloritolites · Rodingites · Bashkortostan · Ural

1 Introduction To compare mineralogical features with previously studied gold-bearing rodingites of Zolotaya Gora (Spiridonov and Pletnev 2002; Murzin et al. 2017; Murzin et al. 2018) and Au-Cu-Ag Tuvan rodingites of the Agardag deposit (Palyanova et al. 2018; Murzin et al. 2020), a study of the mineralogy and geochemistry of several occurrences of similar potentially gold-bearing rodingite-like rocks and metasomatites of the Southern and Middle Urals was undertaken. The studied manifestation of chloritolites and garnet-chlorite rocks is located 35 km southeast of the city of Miass, near the village. Orlovka and Muldakaevo, 500 m north-west of the well-known Muldakaevskoe green jasper deposit (54° 46´56´´ N; 59° 47´55´´E). In geological and tectonic terms, it is located within the Main Ural fault in the West Magnitogorsk structural-formational zone and is confined to the zone of serpentinite melange of the Late Devonian-Permian age. Melange rocks are composed of blocks (in the first hundred meters in size), scraps of plates and blocks of apodunite and apogharzburgite serpentinites, as well as fragments of volcanic and volcanogenicsedimentary Paleozoic rocks of the Polyakovskaya (O1-2) and Irendyk (D1-2) formations developed in the region. The rocks of the melange zone underwent significant hydrothermal-metasomatic alterations, manifested in the development of talc-carbonate rocks, talcites, listvenites, chloritolites, and rodingites. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 117–122, 2023. https://doi.org/10.1007/978-3-031-23390-6_16

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2 Materials and Methods Samples were selected from outcrops of chloritised serpentinite, chloritolite and garnetchlorite rocks near the Muldakaevskoye jasper deposit. The chains of rocky outcrops can be found at a distance of 20 m. In some cases, the presence in the metasomatites of a significant amount of garnet and Fe-Ti ore minerals, distributed in chlorite-containing rocks, is determined. The most interesting studied samples with garnet coincide with the contact of monomineral chloritolites with chlorite-garnet rock. Microscopically, chloritolite itself is a relatively fine-grained mass of differently oriented chlorite flakes, sometimes acquiring a scalloped appearance, in which rare precipitates of calcite, apatite and fine ore minerals are interspersed. Veins of coarse-grained chlorite up to 5 mm thick dissect the mass, sometimes forming strip-like aggregates of course-flaked chlorite among the fine-grained chlorite mass, as well as spherulite aggregates. Among the large chlorite (spherulites) there are grains of twinned calcite, and among the fine-grained chlorite there are small inclusions of apatite and various accessories (see below). In the contact zones, medium-flaky chlorite gradually transforms into a fine-grained chlorite mass with rounded garnet segregations and then to - the zone of anisotropic brown garnet. In it, coarse-flaked chlorite composes vein-nested spherulite aggregates containing larger (compared to the fine-grained mass) magnetites, ilmenites, titanites and copper minerals (both primary types of bornite, chalcopyrite and chalcosine, and secondary types - sulfates, silicates and copper carbonates). A garnet forms irregular nested fine-grained brown clusters up to 5–6 mm in size, and chlorite fills the interstitium between garnet grains, less often garnets together with Fe-Ti ore minerals, form chains and strip-like segregations in the chlorite mass. The mineral composition of chloritolites was studied by microscope in transparent and polished thin sections and heavy component concentrate (crushed to a fraction of −0.5 mm). The concentrate is presented by: garnet, ilmenite, and octahedral magnetite crystals and its fragments, which are in approximately equal amounts. Among other accessory minerals, the concentrate contains single crystals of apatite, zircon, monazite, and xenotime in fractions of fineness less than 0.25 mm. The chemical composition of the rock was determined at the analytical center “Geoanalyst” of the Institute of Geology and Geochemistry of the Ural Branch of the Russian Academy of Sciences using X-ray fluorescence analysis XRF (CPM-35 and XRF1800, main components) and ICP-MS inductively coupled plasma mass spectrometry (ELAN 9000 and NexION 300S, trace elements). The concentrations in the rocks of Sc (70–80 ppm) and V (600 ppm) are typical of the Urals chloritolites and are not anomalous. Electron probe microanalysis, including the acquisition of images of the studied objects in secondary and back-scattered (BSE) electrons, as well as X-ray spectral local microanalysis, was performed on a Tescan VEGA-II XMU scanning electron microscope with an INCA Energy 450 energy dispersive spectrometer and an Oxford INCA Wave 700 wave dispersion spectrometer at IEM RAS. The studies were carried out at an accelerating voltage of 20 kV. The current of absorbed electrons on the studied samples is from 150 to 400 picoamperes (depending on the microrelief, structure and composition). The size of the electron probe on the sample surface was 157–180 nm (Tescan), with

Scandium Garnets from Chloritolites, South Ural

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scanning up to 60 nm. Depending on the composition of the sample and the geometry of the phases, the range of excitation spectra can reach to 5 µm in diameter. Chloritolites form lenticular bodies and are represented by almost monomineral chlorite rocks - Fe-Mg chlorites of various sizes and compositions (XMg from 51 to 80) and sharply subordinate carbonates, mainly calcite, much less dolomite. In some varieties, in addition to the groundmass, the rocks contain abundant accessory mineralization (garnet, apatite, Mn-ilmenite, titanite, V-bearing magnetite, allanite, REE-bearing zircon, REE phosphates and carbonates, uraninite and thorianite). Among the ore minerals, chalcopyrite, pyrrhotite, bornite, chalcocite, secondary carbonates and hydrosilicates of copper are diagnosed. The content of garnets in some samples reaches 20 vol%, light brown to reddish brown anisotropic garnets are represented by veins, nests up to 5–6 mm and individual idiomorphic precipitates up to 1 mm (Fig. 1) and usually correspond to common andradites with an admixture of grossular. It should be noted that high scandium garnets were recorded only in 2–3 lenses of chloritolites, visually indistinguishable from those, but without scandium minerals. Garnets from several bodies are found (Table 1) contain abnormally high contents of scandium (Sc2O3 up to 12.3 wt%, average 6.1%), titanium (TiO2 up to 5.3%, average 2.3%) and vanadium (V2O3 up to 4.9%, average 2.5%). In general, they correspond to scandium-vanadium (± Ti) garnets of the series erringaite (Erg) Ca3 Sc2 [SiO4 ] 3) - goldmanite Ca3 V2 [SiO4 ]3 - andradite Ca3 Fe3 + 2 [SiO4 ] 3 (final after Grew et al. 2013). In contrast to the world’s first finding of natural scandium garnets in akhtaranditecontaining rodingite-like rocks on the r. Vilyui, Yakutia (Galuskina et al. 2005; Galuskina et al. 2010) Sc garnets of the Muldakaevo ore occurrence do not contain zirconium, but are enriched in vanadium and titanium. The contents of scandium in the most enriched varieties even exceed those described earlier (12.3 vs 11.2 wt% Sc2O3 and up to 0.89 a.p.f.u. vs 0.82). Some of the grains are almost homogeneous by respect to Sc. In most grains there are separate zones enriched in scandium or aluminum with respect to Fe3+ (dark zones in Fig. 1a), while garnet in the BSE acquires a “mosaic” structure. There is no regular zoning. The bulk of the highest scandium phases is represented by inclusions or ingrowths in magnetite (less often in ilmenite) separately or in intergrowths with apatite and ilmenite. Garnets often form skeletal forms rather than massive phenocrysts (Fig. 1c, d), and the scandium and vanadium contents in such “skeletons” are usually higher than in “monolithic” garnet excretions. The compositions of typical compositions and the corresponding formula coefficients are shown in Table 1. Calculation of formula units was done according to the interpretation of the crystal chemical position of scandium in synthetic and natural garnets and the corresponding calculation scheme for garnets of the andradite group (Quartieri et al. 2006; Grew et al. 2013). It is clear from the compositions that the almost complete series are forming: eringaite - andradite - to the complete absence of scandium in the garnet composition. For the most scandium composition, an idealized formula was obtained (Ca, Mn, Mg)3(Sc0.89, Fe3+, Al, V, Ti)2(Si, Al)3O12 (analysis 2–31 in Table 1). Scandium has a very high negative correlation with Fe3+ (R = −0.92) and relatively low positive

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Fig. 1. a) magnetite overgrowth of the intergrowth of idiomorphic Sc-Grt (Erg) with Ap; b) scandium garnets in magnetite; c, d) Sc-Grt (Erg) skeletal crystals with Ilm and Ap in Mt.

correlations with Al (R = +0.42) and V (R = +0.31), which indirectly indicates the substitution of scandium primarily for trivalent iron in octahedral Y positions of the grenade. In addition to garnet, elevated Sc and V contents are found in titanites (separate growth zones up to 1.2% Sc2O3), and high V contents are found in magnetites (up to 3 wt% V2O3). This finding of high-scandium minerals makes it possible to reveal during the further study the possible mechanisms of the concentration of ultra-scattered components such as scandium in metasomatites over ultrabasic rocks. Probably, the concentration of scandium occurs in a joint geochemical process with titanium, vanadium, phosphorus and, possibly, rare-earth elements of the cerium group.

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Table 1. Chemical Compositions (wt%) and a.p.f.u. Sc-V garnets (calculated for 12 O)

MgO Al2 O3

2–31

2–32

1–42

1–30

1–43

1–31

1–32

2–60

2–58

2–80

2–64

0.08

0.04

0.82

1.06

0.08

0.63

0.75

0.21

0.07

0.29

0.01

5.99

5.74

0.00

0.24

4.41

0.13

0.21

0.90

0.37

1.85

0.59

SiO2

34.22 35.31 35.21 34.07 35.15 33.66 34.73 32.95 34.28 33.52 32.94

CaO

34.31 34.24 32.60 33.22 33.07 32.13 32.95 31.87 32.16 32.68 33.26

Sc2 O3 12.30 11.81

9.31

8.74

8.21

7.51

6.93

3.27

2.04

0.51

0.17

TiO2

1.88

2.28

1.85

2.14

2.13

1.45

1.79

2.95

1.22

5.35

3.16

V2 O3

0.88

0.75

3.31

3.59

1.64

4.91

4.21

1.66

1.99

0.69

1.12

MnO

0.30

0.20

0.00

0.00

0.17

0.01

0.13

0.64

0.27

0.21

0.17

Fe2 O3

8.10

7.69 16.47 15.87 14.06 17.69 17.34 23.55 26.15 23.14 27.47

Total

98.16 98.06 99.57 99.15 98.97 98.21 99.10 98.20 98.73 98.53 98.92

Ca

3.03

3.01

2.91

2.99

2.92

2.93

2.97

2.93

2.94

2.96

3.05

Mg

0.01

0.00

0.10

0.13

0.01

0.08

0.09

0.03

0.01

0.04

0.00

X site

3.04

3.02

3.01

3.12

2.93

3.01

3.06

2.95

2.95

3.00

3.05

AlY

0.41

0.46

0.00

0.00

0.33

0.00

0.00

0.00

0.00

0.02

0.00

Sc

0.89

0.84

0.68

0.64

0.59

0.56

0.51

0.24

0.15

0.04

0.01

Ti

0.12

0.14

0.12

0.13

0.13

0.09

0.11

0.19

0.08

0.34

0.20

V

0.06

0.05

0.22

0.24

0.11

0.33

0.28

0.11

0.14

0.05

0.08

Mn

0.02

0.01

0.00

0.00

0.01

0.00

0.01

0.05

0.02

0.02

0.01

Fe3+

Y

0.50

0.48

0.96

0.89

0.87

1.01

1.03

1.44

1.64

1.47

1.65

Y site

2.00

1.98

1.98

1.92

2.04

2.00

1.96

2.04

2.04

1.95

1.96

Si

2.82

2.90

2.93

2.86

2.90

2.87

2.92

2.82

2.93

2.83

2.82

AlZ

0.18

0.10

0.00

0.02

0.10

0.01

0.02

0.09

0.04

0.17

0.06

FeZ

0.00

0.00

0.07

0.11

0.00

0.12

0.06

0.08

0.04

0.00

0.12

Z site

3.00

3.00

3.00

3.00

3.00

3.00

3.00

3.00

3.00

3.00

3.00

Total

8.03

8.00

7.99

8.03

7.97

8.00

8.02

8.00

7.98

7.96

8.01

3 Results and Discussion In contrast to the described first finding of Sc garnets, the described crystallization of garnets of the eringaite - goldmanite series in the Muldakaevo ore occurrence is unlikely to be associated with a sufficiently high-temperature formation process (>400 C, up to 800 C), as in the case of the formation of similar exotic zirconium and tin garnets (such as biticleite (SnAl), biticleite (ZrFe), toturite and elbrusite (Zr)) in Vilyui and in nearsurface high-temperature skarns in the Caucasus (Galuskina et al. 2015). TMetasomatic processes forming the bulk chlorite are unlikely to have taken place at temperatures above 250 °C, however, this issue requires careful further study.

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Acknowledgments. The work was carried out within the framework of state assignments (state registration No. AAAA-A18-118052590028-9, AAAA-A18-118020590151-3).

References Murzin, V.V., Varlamov, D.A., Palyanova, G.A.: Formation conditions of gold-bearing magnetitechlorite-carbonate rocks of the Karabash massif of hyperbasites (South Urals). Geologiya I geophizika [Geol. Geophys.] (7), 1006–1020 (2017). (In Russian). https://doi.org/10.15372/ GiG20170704 Palyanova, G.A., Murzin, V.V., Zhuravkova, T.V., Varlamov, D.A.: Au-Cu-Ag mineralization of rodingites and nephrites of the Agardag hyperbasite massif (Yu. Tuva, Russia). Geologiya I geophizika [Geol. Geophys.] 59(3), 300–321 (2018). (in Russian). https://doi.org/10.15372/ GiG20180303 Spiridonov, E.M., Pletnev, P.A.: The deposit of cuprous gold Zolotaya Gora (about the “goldrodingite” formation), 220 p. Nauchniy mir [Scientific world], Moscow (2002). (in Russian) Galuskina, I.O., Galuskin, E.V., Dzier´zanowski, P., Armbruster, T., Kozanecki, M.: A natural scandian garnet. Am. Mineral. 90, 1688–1692 (2005). https://doi.org/10.2138/am.2005.1981 Galuskina, I.O., et al.: Eringaite, Ca3 Sc2 (SiO4 )3 , a new mineral of the garnet group. Mineral. Mag. 74(2), 365–373 (2010). https://doi.org/10.1180/minmag.2010.074.2.365 Galuskina, I.O., et al.: Toturite Ca3 Sn2 Fe2 SiO12 - A new mineral species of the garnet group. Am. Mineral. 95(8–9), 1305–1311 (2015). https://doi.org/10.2138/am.2010.3421 Grew, E.S., Locock, A.J., Mills, S.J., Galuskina, I.O., Galuskin, E.V., Hålenius, U.: Nomenclature of the garnet supergroup. Am. Mineral. 98, 785–811 (2013). https://doi.org/10.2138/am.2013. 4201 Murzin, V.V., Chudnenko, K.V., Palyanova, G.A., Varlamov, D.A., Naumov, E.A., Pirajno, F.: Physicochemical model for the genesis of Cu-Ag-Au-Hg solid solutions and intermetallics in the rodingites of the Zolotaya Gora gold deposit (Urals, Russia). Ore Geol. Rev. 93, 81–97 (2018). https://doi.org/10.1016/j.oregeorev.2017.12.018 Murzin, V.V., Palyanova, G.A., Varlamov, D.A., Shanina, S.N.: Gold-bearing rodingites of the Agardak ultramafic massif (Southern Tuva, Russia) and problems of their genesis. Geol. Ore Deposits 62(3), 204–224 (2020). https://doi.org/10.1134/S107570152002004X Quartieri, S., et al.: Site preference and local geometry of Sc in garnets: part II. The crystalchemistry of octahedral Sc in the andradite- Ca3 Sc2 Si3 O12 join. Am. Mineral. 91, 1240–1248 (2006). https://doi.org/10.2138/am.2006.2038

Minerals - Indicators of Petro- and Ore Genesis and New Methods of Its Identification

Compositional Evolution of Ree- and Ti-Bearing Accessory Minerals in Metamorphic Schists of the Atomfjella Series, Western Ny Friesland, Spitsbergen S. A. Akbarpuran Haiyati1(B) , Yu. L. Gulbin1 , A. N. Sirotkin2 , and I. M. Gembitskaya1 1 Saint-Petersburg Branch of the Russian Mineralogical Society, Saint Petersburg Mining

University, Saint-Petersburg, Russia [email protected] 2 Saint-Petersburg Branch of the Russian Mineralogical Society, Stock Venture “Polar Marine Geosurvey Expedition”, Saint-Petersburg, Russia

Abstract. Representative samples of metapelites with the assemblage Ms–Bt– Grt–Qz–Pl and calcic pelitic schists with additional carbonate and clinozoisite were studied. The special attention was paid to the microstructure of aggregates of accessory minerals and its petrogenetic interpretation. Conditions and mechanisms of phase reactions responsible for the formation of accessories are discussed. Keywords: Metapelites · Calcic pelitic schists · Allanite · Clinozoisite crystals with allanite cores · Rutile · Titanite · Atomfjella Antiform · Mossel series · Ny friesland · Spitsbergen

1 Introduction Accessory minerals, along with rock-forming ones, take an active part in metamorphic transformations, acting as sources of rare elements (REE + Y, U, Th, etc.) participating in phase reactions. The study of the composition, zoning and textural relationships of accessories allows obtaining information related to the sequence and age of metamorphic events. This article discusses accessory mineralization from the rocks of the crystalline basement of one of terranes, which takes part in the geological structure of the Spitsbergen archipelago. The microstructure of aggregates and the chemical composition of accessories have been studied. The phase equilibria forward modeling was used to calculate metamorphic conditions.

2 Geological Setting The Ny Friesland terrain is located north of Spitsbergen. Precambrian complexes in Ny Friesland form a major fold, the Western Ny Friesland Anticlinorium (also named as © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 125–132, 2023. https://doi.org/10.1007/978-3-031-23390-6_17

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the Atomfjella Antiform), elongated in the S–N direction, and separated by a tectonic contact from the Hinlopen synclinorium in the east and by the Wijdefjorden deep fault from the Old Red Sandstone Graben in the west. The crystalline basement of West Nu Friesland is composed of the Atomfjella (PR1 ) and Mossel (RF1 ) Series. The Atomfjella Series is dominated by a well-stratified volcanic-sedimentary sequence which includes migmatized gneiss, schists, quartzites, amphibolites, and marbles. This succession is over 8 km thick and deformed into isoclinal folds often complicated by longitudinal and transverse faults. All rocks are metamorphosed at amphibolite facies conditions. Anatectic granites intruding volcanicsedimentary units have U-Pb zircon age of ca. 1750 Ma (Sirotkin and Evdokimov 2011). Metamorphosed mafic and ultramafic intrusions occurring within the Atomfjella Series dated by the U-Pb zircon method gave ages of ca. 1470 and ca. 1350 Ma respectively (Sirotkin and Evdokimov 2020). The Atomfjella Series is unconformably overlapped by the Mossel Series. In the east, the last one has a tectonic contact with the Upper Riphean Lomfjorden Group that differs sharply both in features of the section and metamorphism grade from the Mossel Series.

3 Analytical Methods Representative rock samples from the northern (well exposed) part of the anticlinorium were studied in detail to characterize accessory minerals. Bulk-rock compositions were determined by X-ray spectral fluorescence analysis at the Russian Geological Research Institute (VSEGEI). Mineral compositions were analyzed using a JSM-6460LV scanning electron microscope with an Oxford INCA Energy dispersive microanalysis system at Saint Petersburg Mining University. Theriak-Domino software by de Capitani and Petrakakis (2010) was used to calculate P–T pseudosection.

4 Petrography Sample 3912-3a (metapelitic schist) has garnet porphyroblasts up to 4–5 mm in diameter which are wrapped by a fine-grained foliated quartz-plagioclase-mica matrix with minor carbonaceous matter and ilmenite. Garnet contains S-shaped quartz and other matrix mineral inclusion trails, as well as late aggregates of small chlorite and albite. Sample 3912-3b (calcic pelitic schist) are thin-banded foliated due to alternation of lenticular interlayers composed of fine-grained quartz and sericite replacing plagioclase, with stratums of more coarser-grained K-feldspar, calcite, titanite, and scapolite. Garnet porphyroblasts up to 1 cm in size were observed in the rock. They are wrapped by the foliated biotite aggregate or enclosed in K-feldspar lenses, contain numerous inclusions of matrix minerals, and cross-cut by late chlorite-calcite-clinozoisite veins.

5 Accessory Minerals and the Sequence of Their Formation Monazite-(Ce) is one of the most typical REE-rich accessories of the studied metapelitic schists. It is observed as euhedral prismatic crystals up to 50 µm in length occupied

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interstitial positions between biotite and muscovite flakes. Often these crystals form clusters and occur in intergrowth with plates of carbonaceous matter. A detailed study reveals concentric and sector zoning in monazite crystals. They are rich in cerium (Ce2 O3 33.7–34.9 wt %, Ce 0.48–0.53 apfu), lanthanum (La2 O3 15.4– 18.5 wt %, La 0.22–0.27 apfu), and neodymium (Nd2 O3 11.5–15.9 wt %, Nd 0.16–0.22 apfu). The minor components are SiO2 (up to 1.1 wt %) and ThO2 (up to 6.2 wt %). Minerals of the epidote supergroup are represented by allanite-(Ce), which is closely associated with clinozoisite, rarer epidote, and their REE-rich varieties. In metapelitic schists, allanite-(Ce) forms thin lamellar crystals closely intergrown with larger grains of REE-rich epidote. Aggregates of two minerals up to 150–200 µm in size have irregular sinuous boundaries and form inclusions in garnet. Total REE content in allanite from metapelites are 0.58–0.67 apfu (Ce 0.30–0.37 apfu, La 0.15–0.19 apfu, Nd 0.11–0.14 apfu). In REE-rich epidote, total REE content decreases to 0.40–0.42 apfu with the same ratio of Ce to La and Nd.

Fig. 1. Epidote-REE-rich clinozoisite-allanite-(Ce) aggregates in the matrix of the carbonatebearing schist of the Atomfjella Series. Sample 3912-3b. BSE images. Abbreviations of minerals after Kretz (1983).

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In calcic pelitic schists, allanite-(Ce), clinozoisite, and epidote occur in two forms. In the matrix, many oval-shaped epidote-clinozoisite-allanite aggregates smaller than 700– 800 µm that lie along the schistosity are observed (Fig. 1). There is a complex intergrowth of allanite-(Ce) and REE-rich clinozoisite in the central part of each aggregate which on both sides, in the schistosity direction, is surrounded by scattered clusters of small (10–30 µm) epidote, clinozoisite, and REE-rich clinozoisite grains. Total REE content in allanite-(Ce) ranges within 0.56–0.75 apfu with the Ce content varies from 0.29 to 0.41 apfu. In REE-rich clinozoisite, total REE content markedly decreases (up to 0.40–0.42 apfu) whereas in clinozoisite it reduces to more than 0.05 apfu. In garnet porphyroblasts, there are inclusion of crystals of clinozoisite with allanite cores (Fig. 2). They are 200–250 µm in size and have a prismatic and dipyramidal habit. The internal texture of allanite cores is analogous to that of intergrowths of allanite and REE-rich clinozoisite in the matrix. Allanite is in intimate intergrowth with REErich clinozoisite here too. Compositions of allanite-(Ce) in the matrix and in inclusions within garnet are similar to one another. Compositions of REE-rich clinozoisite vary over a wide range, forming an almost continuous isomorphic series, the end-members of which are allanite and clinozoisite free of REE. Additionally, unidentified Th-phases are located at edges of allanite cores (Fig. 2). The Ti-bearing accessory minerals in the metapelites are ilmenite and rutile. They occur as small (100–200 µm) grains in the matrix and as inclusions within garnet. As shown in Fig. 3, garnet exhibits zoning in the distribution of Fe-Ti oxide inclusions due to it contains inclusions of ilmenite in the core and mantle, and rutile in the rim. Two minerals grow together in the transition zone. Ilmenite contains minor amounts of MnO (up to 2.2 wt %), rutile contains minor amounts of FeO (up to 1.36 wt %).

Fig. 2. Inclusions of clinozoisite crystals with allanite cores in garnet. Sample 3912-3b. BSE images. Th denotes Th-phases.

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Fig. 3. Zonal distribution of inclusions in the garnet porphyroblast. Sample 3912-3a.

In calcic pelitic schists, rutile-ilmenite intergrowths are observed in the rim of garnet porphyroblast. Ilmenite is enriched in MnO (5.5–6.8 wt %) as compared to metapelites. Titanite is closely associated with these minerals. It occurs as small (0.1–0.2 mm) zonal grains in the matrix, forms intergrowths with allanite-(Ce), and surrounds ilmenite grain. The relatively late time of crystallization of this mineral is also indicated by its close association with chlorite, along cleavage cracks in which lamellar crystals of titanite develop. To reconstruct the evolution of metamorphic conditions during the crystallization of accessory minerals, isochemical P–T phase diagrams were calculated and isopleths of pyrope and grossular contents in garnet were plotted. According to the calculations, in the case of metapelite schist, the Grt–Bt–Wm–Chl–Pl–Ilm paragenesis was stable at initial stages of porphyroblast formation (500–510 ºC, 5 kbar). As temperature and pressure increase to their peak values (670–690 °C, 10–11 kbar), ilmenite became unstable and was replaced by rutile. In the case of calcic pelitic schists, the first garnet nuclei appeared in the Grt– Bt–Chl–Wm–Czo–Rt±Ilm–Cal paragenesis field at 530–540 °C, 5.5–7.5 kbar (Fig. 4). This means that clinozoisite and rutile coexisted as part of a stable mineral assemblage at initial stages of garnet porphyroblast growth. When temperature increased above 580 °C, clinozoisite was replaced by plagioclase. At metamorphic peak conditions (660–680 °C, 8.5–10.5 kbar), Grt–Bt–Wm–Pl–Rt–Cal paragenesis equilibrated. When temperature and pressure decreased, ilmenite became stable instead rutile (550–600 °C, 6–6.5 kbar) and, in turn, was replaced by titanite at lower temperature conditions (450–470 °C, 3–5 kbar).

S. A. Akbarpuran Haiyati et al.

Pressure, bar

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Temperature, Cº Fig. 4. Isochemical P–T phase diagram calculated for carbonate-bearing schist sample 39123b using Theriak/Domino (de Capitani and Petrakakis 2010) and the internally consistent thermodynamic dataset (tcdb55c2d) of Holland and Powell (1998). Thermodynamic modeling was  performed in the MnNCKFMASHTC system assuming that aH2 O = 1 and XCO2 = CO2 (CO2 + H2 O) = 0.01. All mineral assemblages contain quartz. Wm denotes white mica, Liq denotes melt. Rutile-bearing paragenesis fields are shaded in grey. The fields of parageneses that are stable at the early and late stages of metamorphic crystallization are highlighted in green and yellow. Red, blue, and green lines show X Py , X Grs , and X Sps isopleths corresponding to the compositions of cores and rims of garnet porphyroblasts. The dotted rectangle refers to peak P–T conditions contoured with the garnet-biotite geothermometer (Kaneko and Miyano 2004; Gulbin 2011), GBPQ (Wu et al. 2004), and GRISP (Wu and Zhao 2006) geobarometers.

According to the literature, zoned crystals of clinozoisite or epidote with allanite cores are characteristic of medium-grade metamorphic rocks (Janots et al. 2006; Krenn and Finger 2007; and others). Allanite is replaced by monazite and minerals of the epidote supergroup under conditions of the epidote-amphibolite facies at 525–610 °C (Wing et al. 2003; Janots et al. 2007; and others). A similar sequence of the mineral

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formation took place in the studied rocks. Allanite (detrital or newly formed) dissolved incongruently at temperatures of 530–540 °C and replaced by REE-rich clinozoisite with the formation of “spongy faceted” pseudomorphs according to the classification of Glikin (2004). The mineral phase enriched in thorium was one of the products of the replacement reactions, which is typical for such processes (Wing et al. 2003; Skrzypek et al. 2017). In the calcic pelitic schists, where clinozoisite was a part of assemblages due to the increased content of calcium in the rocks, clinozoisite rims crystallized around irregularly shaped grains of allanite. These zoned crystals armored within garnet were preserved as relics of early assemblages at late stages of metamorphism. At the same time, zoned Aln–Czo crystals in the matrix underwent partial pseudomorphic replacement by REErich clinozoisite in the form of dissipated clusters of small grains presumably repeating contours of clinozoisite rims at early stages of the porphyroblast formation. According to the classification of Glikin, these clusters can be regarded as “localized automorphs” or aggregates of secondary crystals spatially superposed with a protocrystal but not retaining elements of its shape. After Glikin, low rates of nucleation and growth of newly formed crystals are limiting factors in such cluster formation.

6 Conclusion As a result, several accessory assemblages were identified in the studied rocks, corresponding to different “time sections” of the metamorphic evolution. The earlier assemblage consists of monazite-(Ce) as well as REE-rich clinozoisite and epidote overgrown on allanite-(Ce). These minerals were appeared before the onset of garnet nucleation and at initial stages of the porphyroblast formation under greenschist and low amphibolite facies conditions. In the period that preceded the garnet growth, clinozoisite rims crystallized around the allanite-(Ce) grains. This is evidenced by the zoned clinozoisite crystals with allanite cores observed as inclusions in garnet. At final stages of the porphyroblast formation, when peak metamorphic conditions were reached (670–690 °C, 10–11 kbar), rutile was stabilized and the assemblage of Fe-Ti oxides arose, which included, in addition to rutile, metastable under these conditions ilmenite. At the retrograde metamorphism stage, when the rocks cooled to 450– 470 °C and pressure dropped to 3–5 kbar, rutile and ilmenite in calcic pelitic schists were replaced by titanite occurred in paragenesis with late chlorite. Good preservation of assemblages of early accessories in the schists of the Atomfjella Series indicates relatively high rate of metamorphic processes.

References De Capitani, C., Petrakakis, K.: The computation of equilibrium assemblage diagrams with Theriak/Domino software. Am. Mineral. 95, 1006–1016 (2010) Glikin, A.E.: Polymineral-Metasomatic Crystallogenesis, p. 312. Springer, Dordrecht (2009). https://doi.org/10.1007/978-1-4020-8983-1 Gulbin, Y.L.: Optimization of the garnet–biotite geothermometer: part II. Calibration equations and accuracy of the estimation. Geol. Ore Deposits 53(7), 543–557 (2011). https://doi.org/10. 1134/S1075701511070099

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Holland, T.J.B., Powell, R.: An internally consistent thermodynamic dataset for phases of petrological interest. J. Metamorph. Geol. 16, 309–344 (1998) Janots, E., Negro, F., Brunet, F., Goffe, B., Engi, M.: Evolution of the REE mineralogy in HP– LT metapelites of the Sebtide complex, Rif, Morocco: monazite stability and geochronology. Lithos 87, 214–234 (2006) Janots, E., Brunet, F., Goffé, B., Poinssot, C., Burchard, M., Cemic, L.: Thermochemistry of monazite-(La) and dissakisite-(La): implications for monazite and allanite stability in metapelites. Contrib. Mineral. Petrol. 154, 1–14 (2007). https://doi.org/10.1007/s00410-0060176-2 Kaneko, Y., Miyano, T.: Recalibration of mutually consistent garnet-biotite and garnet-cordierite geothermometers. Lithos 73, 255–269 (2004) Krenn, E., Finger, F.: Formation of monazite and rhabdophane at the expense of allanite during Alpine low temperature retrogression of metapelitic basement rocks from Crete, Greece: microprobe data and geochronological implications. Lithos 95, 130–147 (2007) Kretz, R.: Symbols for rock-forming minerals. Am. Mineral. 68, 277–279 (1983) Sirotkin, A.N., Evdokimov, A.N.: Endogenous regimes and metamorphic evolution of folded complexes in the basement of the Spitsbergen Archipelago (a case study of Ny Friesland), 270 p. VNIIOkeangeologia, Saint Petersburg (2011). (in Russian) Sirotkin, A.N., Evdokimov, A.N.: New data on U-Pb dating of basic and ultrabasic metamorphosed intrusions in the north Ny-Friesland Peninsula (West Spitsbergen). Region. Geol. Metall. 81, 45–59 (2020) Skrzypek, E., Bosse, V., Kawakami, T., Martelat, J.-E., Štípská, P.: Transient allanite replacement and prograde to retrograde monazite (re)crystallization in medium-grade metasedimentary ´ znik Dome (Czech Republic/Poland): textural and geochronological rocks from the Orlica-Snie˙ arguments. Chem. Geol. 449, 41–57 (2017) Wing, B.A., Ferry, J.M., Harrison, T.M.: Prograde destruction and formation of monazite and allanite during contact and regional metamorphism of pelites: petrology and geochronology. Contrib. Mineral. Petrol. 145, 228–250 (2003). https://doi.org/10.1007/s00410-003-0446-1 Wu, C.M., Zhang, J., Ren, L.D.: Empirical garnet-biotite-plagioclase-quartz (GBPQ) geobarometry in medium-to high-grade metapelites. J. Petrol. 45, 1907–1921 (2004) Wu, C.M., Zhao, G.C.: The applicability of the GRIPS geobarometry in metapelitic assemblages. J. Metamorph. Geol. 24, 297–307 (2006)

Sulfostannates of Zwitter-Tourmalinite Complexes Accompanying the Lithium-Fluoric Granites (On the Example of Pravourmiysky Rare-Metal-Tin Deposit) V. I. Alekseev(B) Saint-Petersburg Branch of the Russian Mineralogical Society, Saint-Petersburg Mining University, Saint-Petersburg, Russia [email protected]

Abstract. The complex of sulfostannates from the Pravourmiyskoye greisen deposit in the Far East of Russia is discussed. The complex includes stannoidite, mawsonite, stannite, sakuraiite. The discovery and typomorphic features of ferrokësterite and kësterite are noted. Zwitter-tourmalinite metasomatic complexes accompanying the lithium-fluoric granites are distinguished by high ore fertility and lithochalcophilic specialization. They combine cassiterite, wolframite, sulfides (arsenopyrite, lollingite, chalcopyrite, bornite, sphalerite, pyrrhotine, bismuthinite, etc.) and sulfostannates with an admixture of In, Ag, Cd. It is proposed to use sulfostannates as minerals indicating large-scale formation of rare-metal-tin ore. Keywords: Sulfostannates · Kësterite · Ferrokësterite · Stannoidite · Mawsonite · Stannite · Zwitter · Greisen deposits · Lithium-fluoric granites · Pravourmiyskoye deposit · Amur River region

1 Introduction In prospecting mineralogy, particular attention is given to rare minerals and mineral parageneses, formed in abnormal geochemical environment and capable of serving as indicators of ore-rich large and unique deposits (Gavrilenko et al. 2000). Greisen deposits associated with leucogranites are mainly characterized by lithophilic geochemical specialization (Si, Al, F, Sn, W, Mo, Be, Rb, Li, etc.). The appearance of chalcophilic quartzsulfide mineralization in them (Cu, Zn, Pb) is connected with late stages of hydrothermal processes (Plyushchev et al. 2012). Among greisen formations, zwitter-tourmalinite metasomatic complexes (ZTC) related to lithium-fluoric granites clearly stand out by their composition and high ore fertility (Alekseev 2014). In 1948, A.I. Kiselev found stannite enriched with zinc and silver in the topazcontaining greisens of the Këster deposit in Yakutia (Kiselev 1948). Soon it was called “kësterite” and approved by the CNMMN IMA as a new mineral (Orlova 1956; BonstedtKupletskaya 1958). A little later, a ferriferous analogue of kësterite – ferrokësterite was © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 133–139, 2023. https://doi.org/10.1007/978-3-031-23390-6_18

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described in Cornwall greisens of Great Britain (Kissin and Owens 1989). Bibliometric data from Web of Science show a rapid increase in the number of publications devoted to kësterite and ferrokësterite: 18 to 2000, 69 during the period 2000–2010 and 1785 over the past ten years. Such a high interest in a rare minerals is caused by its semiconductor properties: laboratories in many countries are intensively developing technologies for the use of synthetic kësterite as a cheap and environmentally friendly substitute for tellurides, arsenides and selenides of Cd, In, Ga, traditionally used in the production of solar cell battery (Wallace et al. 2017; Dhawale et al. 2019).

2 Materials and Methods Mineral associations of the ZTC were investigated on the example of a large Pravourmiyskoye rare-metal-tin deposit associated with the eponymous complex of lithiumfluoric granites in the Badjal ore district (Amur River region) and of the Këster raremetal-tin deposit associated with the eponymous complex of lithium-fluoric granites in the Yano-Adychansky ore district (Yakutia). At the Pravourmiyskoye deposit in the crossdrift No. 568 of day-hole No. 5, 5 quartz-topaz veins with wolframite, cassiterite and sulfides were collected samples. In the bore specimen of drill hole No. 37 and 38, which opened the Këster deposit of topaz-lepidolite-muscovite greisens with cassiterite, 3 samples of quartz veins with cassiterite and sulfides were taken. Ore petrography of the 8 samples using reflected and transmitted light was carried out using an Leica DM2500 M microscope. Ore textures were assessed and representative samples were examined further by SEM-EDS methods. The internal structure, composition and relationship of sulphides were investigated in polished section using a JEOL JSM-6460LV equipped with an Oxford Instruments INCA EDS system in the Microanalytical Centre at St. Petersburg Mining University. Survey conditions: COMPO imaging signal, accelerating voltage 20 kV, beam current 1.5 nA. The composition of kësterite and ferrokësterite was investigated in the same Centre using a JEOL JXA-8230 with four WDS spectrometers and PETJ, LIF crystals. The analyses were performed using a beam current of ~20 nA, accelerating voltage of 20 kV, probe diameter 1 µm, and live times of 30 s. ZAF corrections were used for the correction procedure. The standards used were pyrite (FeKα, SKα), sphalerite (ZnKα), chalcopyrite (CuKα), InAs (InLα), Sn (SnLα), Ag (AgLα). The number of EPMA analyses of ferrokësterite is 16, kësterite is 7. To distinguish the minerals of the stannite group, the stoichiometric criteria proposed were used in (Kissin and Owens 1989). When studying the structure and relationships of kësterite-ferrokësterite and associating sulfides, the concept of minerals ontogeny was used (Alekseev 2014; Brodskaya and Marin 2016).

3 Results Due to the enough study of the kësterite deposit (Kiselev 1948; Bonstedt-Kupletskaya, 1958; Kokunin 2011) below is described only ferrokësterite of the Pravourmiyskoye deposit. This deposit is the richest source of tin (more than 100 thousand tons) and associated rare and basic metals: tungsten, copper, bismuth, niobium, indium, scandium. The expedition of the Saint-Petersburg Mining University organized under the direction

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of Yu.B. Marin in the ZTC of the Pravourmiyskoye deposit established an association of sulfostannates - stannoidite, mawsonite, stannite (Gulbin and Evangulova 1987). For the first time sakuraiite and kësterite were identified in zwitters (Alekseev 2014) (Table 1). In the composition of sulfostannates, variable concentrations of impurities, represented by In, Ag, Cd, were recorded. Rich sulphide mineralization was determined on the eastern flank of Pravourmiyskoye deposit. In the axial part of the zwitter zone are concentrated steeply pitching cassiterite-topaz veins with a thickness of 3–16 cm. They intersect with quartztourmaline veinlets (0.5–4 cm). Veins contain cassiterite, wolframite and up to 3–15% of sulfides, among which prevail arsenopyrite, chalcopyrite, sphalerite, pyrrhotine, galenite prevail. Sulfides are distributed in veins and near-lying greisens in form of dissemination, veinslets and polymineral bonny measuring 1–12 cm (Fig. 1). In topaz veins, for the first time was found ferrokësterite, represented by isometric and lenticular secretions 5–20 µm across, located in the marginal parts of the aggregates of pyrrhotine and high-iron sphalerite (Fe/Zn 0.20–0.29), on the border with quartz, topaz and fluorite (Fig. 2). The internal structure of ferrokësterite is uniform. No mineral inclusions larger than 6 nm were detected. Ferrokësterite stoichiometrically corresponds to standards from the Kliga deposit in Cornwall (Kissin and Owens 1989) and Mount Pleasant in Canada (Sinclair et al. 2006). The empirical formula of the mineral: Cu1.89 (Fe0.97 Zn0.13 )Sn0.99 S4.01 . Signs of ferrokësterite of the Far East: excessive iron content (Fe/(Fe + Zn) = 0.73 ÷ 0.92) and deficiency of copper, indium and silver, as well as other rare elements (Cd, Bi, As, Se), characteristic of its analogues from the tin ore deposits around the world. Table 1. Mineral associations of zwitter-tourmalinite complex from the Pravourmiyskoye deposit Mineral association

Minerals of zwitters

Minerals of tourmalinites

Sulfostannates of Cu, Fe, Zn, In

Ferrokësterite, sakuraiite

Stannoidite, stannite, mawsonite

Sulphides of Cu, Fe, As, Zn, Bi, In

Arsenopyrite 1, lollingite, bismuthinite, sinnerite, sphalerite 1, pyrrhotine

Chalcopyrite, bornite, sphalerite 2, roquesite i dp

Rare metal minerals

Cassiterite, wolframite, monazite, xenotime, fergusonite, pyrochlore i dp

Cassiterite, monazite, Ce-epidote

4 Discussion The finding of ferrokësterite on eastern flank of the Pravourmiyskoye deposit is not accidental. It is connected with the inclination of ore bodies to the east and a decrease in their erosion cut in this direction. Ferrokësterite was found on the uppermost tier of a greisen-ore column enriched with base metals, and on the eastern flank of the ore zone

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it replaces stannoidite and stannite as part of sulfostannates. It replaces stannoidite and stannite on eastern flank of the ore zone as part of sulfostannates. Replacement of stannite to ferrokësterite according to the scheme: Cu2 FeSnS4 + ZnS → Cu2 (Fe, Zn)SnS4 + (ZnFe)S (Osadchii and Sorokin 1989). At the Këster deposit, kësterite is also confined to upper part of the greisens ore delf. It displaces the stannite as part of the sulfide complex, and associated with cassiterite, sphalerite, pyrrhotine and arsenopyrite (Kokunin 2011).

Fig. 1. Topaz veins with cassiterite, wolframite, sulfides, and ferrokesterite from zwitter of the Pravourmiyskoye deposit: a – topaz vein with cassiterite, arsenopyrite, with bonny of sphalerite and ferrokësterite; b - topaz vein with cassiterite, wolframite, arsenopyrite, chalcopyrite, with bonny of sphalerite, pyrrhotine and ferrokësterite. Apy – arsenopyrite, Ccp – xalkopipit, Cst – cassiterite, Fks – ferrokësterite, Po – pyrrhotine, Sp – sphalerite, Tpz – topaz, Tur – tourmaline, Qtz – quartz, Wlf – wolframite.

Greisen deposits associated with leucogranites are mainly characterized by lithophilic geochemical specialization (Si, Al, F, Sn, W, Mo, Be, Rb, Li, etc.). ZTC of large rare-metal-tin ore deposits accompanying the lithium-fluoric granites (Ehrenfriedersdorf, Germany; Baga-Ghazryn, Mongolia; Mount Pleasant, Canada; Lost River, Alaska; Odinokoe, Yakutia; Tigrinoe, Primorye, etc.), are characterized by specific mixed mineral paragenesis (Alekseev 2014). On the one hand, they are composed of lithophilic minerals (quartz, light mica, topaz, albite, etc.) and contain accessory and ore mineralization typical of rare-metal-tin ore deposits (cassiterite, wolframite, beryl, fluorite, tantalum-niobates, etc.). On the other hand, they are saturated with chalcophilic rockforming and ore minerals – zinnwaldite, tourmaline and sulfides - arsenopyrite, chalcopyrite, sphalerite, etc. Emblematic for the mineralogy of ZTC is the presence of complex sulfides – sulfostannates: stannite, stannoidite, kësterite, etc. (Parrish 1977; Kissin and Owens 1989; Sinclair et al. 2006; Moura et al. 2007; Kokunin 2011; Popova et al. 2013; Alekseev 2014; Wu et al. 2017).

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Fig. 2. Ferrokesterite and kesterite in greisen associated with Li–F granites of the Pravourmiyskoye (a, b) and Kester (c, d) deposits: a – ferrokësterite in the place of contact with pyrrhotine and high-iron sphalerite; b – fragment of Fig. 2, a: ferrokësterite vein; c – encrustation of pyrrhotine with kësterite in the place of contact with cassiterite and sphalerite in quartz veins; d – aggregate of kësterite with cassiterite and pyrrhotine in a cassiterite-quartz vein. Ccp – chalcopyrite, Cst – cassiterite, Fks – ferrokësterite, Gn – galena, Ks – kësterite, Po – pyrrhotine, Sp – sphalerite, Tp – topaz, Qtz – quartz, Wlf – wolframite.

Sulfostannates are attributed of silicate-sulfide tin-polymetalic ore deposits. Their emergence in association with rare-metal minerals of the cassiterite-quartz formation can be explained by an increased concentration of copper and sulfur at the final stages of greisenization process. As reducing conditions are established, sulfostannates are successively formed: sakuraiite → ferrokësterite → stannite → stannoidite → mawsonite. The list of kësterite finds in greisen deposits in the Far East of Russia, Canada with high-temperature paragenesis of topaz, cassiterite, arsenopyrite, wolframite, kësterite and cubic stannite is expanding (Bonstedt-Kupletskaya 1958; Parrish 1977; Cerny and Harris 1978; Kokunin 2011; Popova et al. 2013). Ferrokësterite is also discover in relatively high-temperature deposits in South America, Canada, Great Britain, combining greisen-arsenopyrite and hydrothermal base metal-sulfide mineralization (Kissin and Owens 1989; Betterton et al. 1998; Sinclair et al. 2006; Torres et al. 2019). From the geodynamics viewpoint the considered greisen-magmatic systems (YanoAdychan district in Yakutia, Badjal district in the Amur river region, Arminsky district in Primorye, Cornwall in the UK, Mount Pleasant in Canada, etc.), are formed along

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the boundaries of stable geoblocks, in the inner region of continental margin. It is recommended to consider sulfostannates as mineral indicating large-scale formation of rare-metal-tin ore. A great practical interest to kësterite is related to its semiconductor properties, making it a promising multicomponent material for solar energy conversion (Wallace et al. 2017; Dhawale et al. 2019). Given the high prospects for application of synthetic kësterite for the production of solar panels, ferrokësterite should be investigated as a likely natural prototype of a new optoelectronic material for converting solar energy into electricity.

5 Conclusions Thus, the zwitter-tourmalinite complexes accompanying the Li-F granites is characterized by a mixed lithochalcophilic specialization of ores. The presence, species diversity and variable composition of sulfostannates in greisens (ferrokësterite, sakuraiite) and tourmalinites (stannoidite, stannite, mawsonite) have been established. You can conclude about the mineralogical features of large oregenesis of the Pravourmiyskoye deposit and extrapolate this conclusion to rare-metal-tin deposits associated with lithium-fluoride granites. Ferrokësterite is a likely natural prototype of a new optoelectronic material for converting solar energy into electricity. Acknowledgments. The reported study was funded by RFBR, project number 20-15-50064.

References Alekseev, V.I.: Lithium-fluoric granites of the Far East, 244 p. Saint-Petersburg Mining University, Saint Petersburg (2014). (in Russian) Brodskaya, R.L., Marin, Yu.B.: Ontogenetic analysis of mineral individuals and aggregates at micro and nanolevel for the restoration of ore-forming conditions and assessment of mineral raw technological properties. J. Min. Inst. 219, 369–376 (2016). (in Russian) Bonshtedt-Kupletskaya, E.M.: New minerals. Zapiski VMO (Proc. Russian Miner. Soc.) (1), 76–84 (1958). (in Russian) Cerny, P., Harris, D.C.: The Tango pegmatite at Bernic Lake, Manitoba. XI. Native elements, alloys, sulfides and sulfosalts. Can. Mineral. 16(4), 625–640 (1978) Dhawale, D.S., Ali, A., Lokhande, A.C.: Impact of various dopant elements on the properties of kesterite com-pounds for solar cell applications: a status review. Sustain. Energy Fuels 3(6), 1365–1383 (2019) Gavrilenko, V.V., Marin, Yu.B., Panova, E.G., Levsky, L.K.: Mineralogy-geochemical signs of large and unique deposits, associated with granite magmatism. Zapiski RMO (2), 1–9 (2000). (in Russian) Gulbin, Yu.L., Evangulova, E.B.: Hydrothermal-metasomatic formations of the Pravourmiysky deposit. J. Min. Inst. 112, 39–50 (1987). (in Russian) Kiselev, A.I.: Silver-zincian stannite from a deposit of the Arga-Ynnakh-Khaysky intrusion in the basin of Yana river. Materials on geology and mineral resources of northeast USSR. Magadan (3) (the first series), 113–117 (1948). (in Russian)

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Kissin, S.A., Owens, D.R.: The relatives of stannite in the light of new data. Can. Mineral. 27(4), 673–688 (1989) Kokunin, M.V.: Rare minerals of the forgotten deposit. Native Geol. (1), 72–82 (2011). (in Russian) Moura, M.A., Botelho, N.F., de Mendonca, F.C.: The indium-rich sulfides and rare arsenates of the Sn-In mineralized Mangabeira A-type granite, central Brazil. Can. Mineral. 45(3), 485–496 (2007) Orlova, Z.V.: Collected book of chemical analyses of ores and minerals from mineral deposits of the northeast USSR. Proc. All-Union. Magadan Res. Inst. 2, 76 (1956). (in Russian) Osadchii, E.G., Sorokin, V.I.: Stannite Bearing Sulphide Systems, 136 p. Nauka, Moscow (1989). (in Russian) Parrish, I.S.: Mineral catalog for the Mount Pleasant deposit of Brunswick tin mines. Can. Mineral. 15, 121–126 (1977) Plyushchev, E.V., Shatov, V.V., Kashin, S.V.: Metallogeny of hydrothermal-metasomatic formations. In: Proceedings VSEGEI. A New Series, vol. 354, 560 p. VSEGEI, Saint-Petersburg (2012). (in Russian) Popova, V.I., Popov, V.A., Korostelev, P.G., Orlovsky, V.V.: Mineralogy of the Tigrinoe WSn deposit on Sikhote-Alin and the prospects for its development, 132 p. RIO URO RAS, Yekaterinburg (2013). (in Russian) Sinclair, W.D., Kooiman, G.J.A., Martin, D.A., Kjarsgaard, I.M.: Geology, geochemistry and mineralogy of indium resources at Mount Pleasant, New Bunswick, Canada. Ore Geol. Rev. 28(1), 123–145 (2006) Torres, B., et al.: The Poopó polymetallic epithermal deposit, Bolivia: mineralogy, genetic constraints, and distribution of critical elements. Minerals. 9(8), 472 (2019) Wallace, S.K., Mitzi, D.B., Walsh, A.: The steady rise of kesterite solar cells. ACS Energy Lett. 2(4), 776–779 (2017) Wu, M., Samson, I.M., Zhang, D.: Textural and Chemical Constraints on the Formation of Disseminated Granite-hosted W-Ta-Nb Mineralization at the Dajishan Deposit, Nanling Range, Southeastern China. Econ. Geol. 112(4), 855–887 (2017)

Mineralogical Features of Columbite from Rare-Metal Granites and Its Isomorphism N. V. Alymova(B) and N. V. Vladykin East-Siberia Branch of the Russian Mineralogical Society, A. P. Vinogradov Institute of Geochemistry SB RAS, Irkutsk, Russia [email protected]

Abstract. The Zashikhinsky massif is unique tantalum-niobium deposit of alkaline-granite type hosted by the Late Paleozoic rare-metal zone of magmatism in the East Sayan Mountains. Columbite is the mineral concentrating Nb, Ta and Y-group elements. It forms both large (2–5 mm) and small (smaller 0.5 mm) black grains, in places it occurs as flattened elongated crystals. In the rocks, it is associated with major rock-forming minerals like quartz, microcline, albite and accessory minerals arfvedsonite, aegirine, zircon and mica. Columbite is found in all facial varieties of granites, and its chemical compositions vary widely. It makes up a complete isomorphous series from columbite-Fe to columbite-Mn (0.38–12.06 wt.% MnO, 7.19–19.71 wt.% FeOtotal , 1.85–18.94 wt.% Ta2 O5 , 58.88–75.46 wt.% Nb2 O5 ). Heightened TiO2 (up to 3.26 wt.%), SnO (to 0.41 wt.%) and low Ce2 O3 , Nd2 O3 , Yb2 O3 , UO2 , ThO2 contents have been defined as well. The Zashikhinsky deposit is derived from the magma of “transitional composition” holding the mineral associations intermediate between alkaline agpaitic and Li-F granites. Keywords: Columbite · Rare-metal granites · Zashikhinsky massif

1 Introduction The Zashikhinsky deposit located in the East Sayan Mountains of Irkutsk Region is a promising geological site of rare metals with large stocks of Ta-Nb (with Zr and Hf) ores, with favorable conditions for open-cast mining. This deposit is hosted by the massif of the agpaitic alkaline granites within the Late Paleozoic rare-metal zone in the East Sayan Mountains. The rocks contain the highest Ta contents in Russia (Mashkovtsev et al. 2011), and they are enriched in Y-group rare-earth elements. The agpaitic granites are unique in that columbite is the major mineral concentrating rare elements, similar to Li-F granites of Trans-Baikal area and Mongolia. Whereas in the granites of deposits similar in ore-formation type (Katuginsky massif) it is the pyrochlore being the concentrating mineral; its contents in Zashikhinsky rocks are insignificant. This paper reports the morphological features and geochemical data on columbite from alkaline granites of the Zashikhinsky massif and provides research results on mineral-concentrator Ta and Nb associated with the other minerals in rare-metal rocks. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 140–148, 2023. https://doi.org/10.1007/978-3-031-23390-6_19

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2 Brief Geologic-Mineralogical Description of the Zashikhinsky Massif The Zashikhinsky Ta-Nb deposit is encompassed by the massif looking as a separately located body with area about 1.3 km2 , which is incorporated into the Khailaminsky massif of granitoids of the Middle Paleozoic Ognitsky complex (Arkhangelskaya et al. 2012). It sits within the Major Sayan Fault being the marginal suture of the Siberian Platform. In plan, it has ellipsoidal shape, and extends in the northwestern direction; and its looks as a mushroom on the geological section. The contacts with hosting rocks are sloping at angles 50°–80° with general southwestern dipping towards the zone of the Major Sayan Fault (Vladykin et al. 2016). The Zashikhinsky massif is typified by three granite varieties: (1) amphibole-bearing quartz-microcline-albite; (2) leucocratic quartz-albite-microcline rare-metal; (3) leucocratic quartz-albite altered to albitites (Vladykin et al. 2016). Considering the composition, the rare-metal rocks of the Zashikhinsky deposit are referred to as the agpaitic alkaline granites. They have high contents of most incompatible elements, e.g.Y, Zr, Hf, Ta, Nb, Th, U, Zn, Ga, REE relative to Clarke contents (Wedepohl 1995), increased alkalinity (Na2 O + K2 O do 12.68 mass %) and low contents of Ca, Mg, Al, Ba and Sr. Petrochemical parameters of rare-metal rocks and their mineral composition correspond to the A-type granites (Whalen et al. 1987; Frost and Frost 2011), and they are attributed to the areas of alkai-oversaturated granites (Maniar and Piccolli 1989). The two debatable viewpoints exist on the genesis of ore-containing rocks in the Zashikhinsky massif. Some authors believe that the massif is composed of alkaline agpaitic granites, and the rare-metal mineralization is linked with the processes of longterm crystallization differentiation of melt with a regular accumulation of incompatible elements to the final products of magmatic process (Yarmolyuk et al. 2012, 2016; Beskin 2014; Vladykin et al. 2016; Alymova and Vladykin 2021). Rare metals display high affinity to oxygen and magmatic melt. Thus, they concentrate in the residual melt enriching the late differentiates of granite magmas. On the other hand, some researchers suggest that rare-metal mineralization resulted from post-magmatic metasomatic processing of granites (Arkhangelskaya et al. 1997, 2012; Kudrin et al. 1998).

3 Materials and Methods Columbite was studied with single-mineral fractions obtained by crushing rare-metal granite samples of all facial varieties. Crushed material was panned on the concentration table. After panning, the samples were divided in heavy liquid by Bromoform CHBr3 (tribrommethane), then followed electromagnetic separation of the concentrate with device SIM-1 and picking columbite grains under binoculars. Identified grains were placed into containers of epoxy resin. Columbite was studied with microprobe JXA-8200 (analyst Suvorova L.F.) equipped with high-resolution raster electronic microscope, energy-dispersive spectrometer (EDS) with SiLi-detector at resolution 129 eV and five spectrometers with wave dispersion (WDS). The studies were performed at the Center for Collective Use “Isotopegeochemical investigations” at the Institute of Geochemistry SB RAS, Irkutsk.

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4 Features of Columbite Composition Columbite (Fe, Mn)(Nb, Ta)2 O6 concentrates tantalum and niobium in the Zashikhinsky massif ore. It occurs in all facial varieties of granites. It produces both large (2–5 mm), and small (less 0.5 mm) black grains. In places it is found as flattened elongated pinacoid {010} and prismatic {001} crystals (Fig. 1).

Fig. 1. Micrographs of Columbite grains.

In alkaline granites of the massif, it is associated with major rock-forming (quartz, microcline, albite) and accessory like arfvedsonite, aegirine, zircon and mica (Fig. 2 and Fig. 3). In the light and crossed nicols, pleochroism exhibits the indigo-blue color.

Fig. 2. Columbite from the rocks of the Zashikhinsky massif in transmitted light (a – nicolas are parallel, b – nicolas are crossed). Lens 4×. Qtz – quartz, Ab – albite, Fl – fluorite, Col – columbite, Pcl – pyrochlore, Gag – gagarinite, Mc – mica, Zrn – zircon.

Columbite is characterized by essential variations of component contents (mass %): MnO 0.38–12.06, FeOtotal 7.19–20.17, Ta2 O5 1.85–18.94, Nb2 O5 58.88–76.5, predominance of Nb over Ta, atomic ratios Mn/(Mn + Fe) = 0.03–0.63 and Ta/(Ta + Nb) = 0.01–0.16. The mineral shows high abundances of TiO2 (up to 3.26 wt.%) and insignificant concentrations of Ce2 O3 , Nd2 O3 , Yb2 O3 , UO2 and ThO2 . The Sn admixture is available in all studied samples, and SnO reaches 0.41 wt.% (Table 1). No distinct zonation is observed in columbite grains. In some cases, there are dark grey spots in the central zones and lighter spots on the crystal margins (Vladykin et al.

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Fig. 3. Columbite from the rocks of the Zashikhinsky massif in transmitted light (a – nicolas are parallel, b – nicolas are crossed). Lens 4 ×. Qtz – quartz, Ab – albite, Fl – fluorite, Col – columbite, Gag – gagarinite.

2016). With vague contours, the zonation looks poor (Fig. 1). The peripheral zones appear to be later formations, and they reflect the changes proceeding in the crystallizing magma environment. These zones have high Ta2 O5 (10–19 wt.%) and low MnO (0.5–7 wt.%) contents. In all analyzed grains, the Nb content dominates Ta, and the coefficients of Nb/Ta ratios vary with different intensity from 5.19 to 66.82. The highest values are common for columbite with heightened MnO. To add, in the grains with indistinct zonation there is inessential drop in Nb/Ta values from center to margin. We may underline that the dominance of Nb over Ta is due to the increased alkalinity of residual melt in formation of alkali-granitoid magmas. Table 1. Chemical composition of columbites in rare-metal granites (wt.%) Columbite-Mn Oxide

1

2

4

5

6

7

8c

8r

TiO2

0.46

0.29 1.03

0.64

0.72

0.82

0.52

0.67

0.73

FeO

7.92

8.25 8.47

8.3

8.71

8.58

8.23

8.2

7.19

MnO

12.06 11.7 11.64 11.8

11.64 11.59 11.83 11.42 12

MgO

bdl

0.02

Nb2 O5

75.28 72,9 76.4

Ta2 O5

4.5

SnO2

0.06

Ce2 O3

0.06

Nd2 O3

bdl

Yb2 O3 ThO2

bdl

3

0.02

bdl

bdl

0.04

0.05

bdl

76.41 76.5

76.5

76.49 75.46 73.2

4.93 1.95

1.84

2.26

1.87

1.37

1.85

6.01

0.08 0.02

bdl

0.05

0.01

bdl

0.02

0.12

0.07 0.04

bdl

bdl

0.01

bdl

bdl

bdl

bdl

bdl

0,78

bdl

bdl

1,01

bdl

0.16

0.01

bdl

0.15

0.13

bdl

0.06

0.06

0.06

0.26

bdl

bdl

0.03

bdl

bdl

bdl

0.03

0.12

bdl

(continued)

144

N. V. Alymova and N. V. Vladykin Table 1. (continued) Columbite-Mn UO2

0.03

0.01 bdl

0.01

bdl

Cymma

100.4 98.3 99.75 99.91 99.9

bdl

bdl

0.07

bdl

99.44 99.58 97.92 99.7

Mn/(Mn + Fe) 0.61

0.59 0.58

0.59

0.58

0.58

0.59

0.59

0.63

Ta/(Ta + Nb)

0.03

0.04 0.02

0.07

0.02

0.01

0.01

0.01

0.05

Nb/Ta

27.81 24.6 65.13 13.59 56.27 68.01 66.82 67.81 20.2

Columbite-Fe Oxide

9

10

11c

11r

12

13

14

15

TiO2

1.75

0.66

3.19

2.72

1.8

1.95

2.91

1.12

FeO

14.76

20.17

19.71

19.86

15.65

19.85

20

16.51

MnO

4.58

0.75

0.62

0.38

3.62

0.54

0.77

3.81

MgO

bdl

0.18

0.17

0.2

0.01

0.18

0.19

0.09

Nb2 O5

58.88

71.56

68.02

61.81

59.18

66.74

68.91

69.58

Ta2 O5

18.75

5.48

8.32

14.87

18.94

10.13

5.88

7.52

SnO2

0.29

0.04

0.41

0.31

0.28

0.25

0.31

0.22

Ce2 O3

0.03

bdl

bdl

0.06

0.1

0.15

0.08

bdl

Nd2 O3

0,28

bdl

bdl

bdl

bdl

0.42

0.92

0.68

Yb2 O3

0,09

bdl

bdl

bdl

0.01

bdl

bdl

bdl

ThO2

bdl

bdl

0.02

bdl

bdl

0.04

bdl

bdl

UO2

bdl

bdl

0.01

0.01

0.02

bdl

bdl

bdl

Cymma

99.41

98.84

100.5

100.2

99.61

100.25

99.86

99.53

Mn/(Mn + Fe)

0.24

0.04

0.03

0.03

0.19

0.04

0.04

0.19

Ta/(Ta + 0.16 Nb)

0.04

0.07

0.07

0.16

0.08

0.05

0.06

Nb/Ta

21.71

13.59

13.59

5.19

11.03

19.48

15.38

5.22

Note: c–center of grain, r–grain radius. bdl–below detection limited.

As regards the major components, this ore mineral refers to the isomorphous set ranging from columbite-Fe to columbite-Mn (Table 1). The columbite grains in which Ta/(Ta + Fe) > 0.5 and referred to tantalites were not found (Fig. 4a). The correlation diagrams display clear linear relationships between the abundances of MnO and FeO, Ta2 O5 and Nb2 O5 (Fig. 4b, c) and absence of correlations between Ta2 O5 and MnO, Nb2 O5 and FeO (Fig. 4d, e).

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Fig. 4. Composition variations of columbite from the Zashikhinsky massif rocks (wt.%).

This is the indication that columbite has isovalent isomorphism, when the Fe2+ ions are replaced by Mn2+ ions, and Nb5+ ions are replaced by Ta5+ ions. No correlation is the case between Nb2 O5 /Ta2 O5 and FeO/MnO, MnO/Ta2 O5 and FeO/Nb2 O5 (Fig. 4f, g). The TiO2 content correlates with SnO2 content (Fig. 4h). This fact suggests that in the structures the Sn4+ ions occupy part of octahedral positions at places of Ti4+ .In addition to the independent mineral forms like columbite

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and Nb-rutile, the niobium being the isomorphous admixture is found in small portions in albite, arfvedsonite, mica, fluorite, cryolite, xenotim, titanite, and tantalum in mica, zircon, fluorite and titanite.

5 Discussion Columbite occurs in all facial varieties of granites of the Zashikhinsky massif where it is uniformly impregnated in the rocks. It was found that this mineral shows wide variations of contents in the isomorphous series from columbite-Fe to columbite-Mn. A wide range of chemical compositions of columbite, even within one massif, is typical for the deposits of alkaline-granite type. It is noteworthy, that no distinct zonation of composition of columbite grains is the case. Only in some instances, a poorly expressed zonation is visible as dark-grey spots in the center and lighter spots on the crystal margins. The marginal zones are evidently later formations reflecting the changes in the crystallizing magma environment. Even columbite displays noticeable variability in Ta2 O5 (1.85– 18.94 wt.%). Some authors attribute alkaline rare-metal granites and metasomatites to the sources of columbite-Fe and -Mn with the abundances of Ta2 O5 reaching 3 wt.% (Geochemistry 1966) or Ta2 O5 less 10 wt.% (Beskin 2014). At the same time, columbite with concentrations of Ta2 O5 reaching 30 wt.% is considered to be the mineral from Li-F granites (Lufuandi Matondo and Ivanov 2020). With significant variations of Ta2 O5 columbite of the Zashikhinsky massif may be referred both to alkaline agpaite varieties and Li-F granites. The mineralogical and geochemical studies pinpoint that the Zashikhinsky massif is composed of the granites similar in mineral associations both to alkaline agpaite varieties and Li-F granites (Alymova et al. 2021). Considering the Ta, Li, Rb, Be and F abundances, the deposit ores approach the plumasite Ta-bearing Li-F granites (Vladykin 1983). It is known that the Li-F granites with agpaite factor (Ka) not exceeding 1.0 contain columbite being the major Ta-and Nb-concentrating mineral, topaz concentrating fluorine, lithium mica concentrating Li. The pyrochlore mineral crystallizes at later stages of granite massif emplacement. In the rocks of the Zashikhinsky deposit in addition to mica typical for agpaite alkaline granites (polylithionite, lithium lepidomelane), muscovite, lepidolite and protolithionite were discovered (Arkhangelskaya et al. 2012), i.e. these are typical minerals of Li-F granites. Above that, the ongonite-like dykes were found in the exocontact zones of the deposit (Dergachev, Annikova 1993). The ongonites are known to be subvolcanic analogs of Li-F granites (Kovalenko, Kovalenko 1976; Vladykin 1983). The major ore mineral occurs in association with zircon, arfvedsonite, aegirine, gagarinite and cryolite. Arfvedsoniteand aegirine are the minerals of alkaline rocks which may be derived only under conditions of high agpaite coefficients at Ka > 1.0 (Vladykin 1983). We should remind that for alkaline granites with Ka > 1.0 that the leading role of the mineral concentrating Ta and Nb belongs to pyrochlore associated with zircon, arfvedsonite, gagarinite and alumofluoride, e.g. cryolite. Such mineral composition is specific to agpaite granites of the Katugin massif similar in ore-formation type. Thus, considering the mineralogical and geochemical features of rocks it was identified that the Zashikhinsky massif is composed of granites similar in mineral associations both to

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alkaline agpaite varieties and Li-F granites. Kovalenko V.I. reported (1977) that agpaitic and Li-F granites are crystallized from granite magmas of various geochemical types. These two varieties of granites do not occur within the same rare-metal massif. With this data in mind, it was inferred that the Zashikhinsky deposit was derived from the magma of “transitional composition” holding mineral associations intermediate between associations of alkaline agpaitic and Li-F granites.

6 Conclusions The uniqueness of the Zashikhinsky massif rocks concentrating rare elements in the major ore mineral columbite distinguishes this deposit amongst the others, in which the predominant part of tantalum and niobium are present in pyrochlore. Showing a wide range of chemical compositions, columbite was detected in all facial varieties of granites. It includes a complete isomorphous set from columbite-Fe to columbite-Mn (0.38–12.06 wt.% MnO, 7.19–19.71 wt.% FeOtotal , 1.85–18.94 wt.% Ta2 O5 , 58.88–75.46 wt.% Nb2 O5 ). Furthermore, it was feasible to measure heightened TiO2 contents (to 3.26 wt.%), SnO (to 0.41 wt.%) and low Ce2 O3 , Nd2 O3 , Yb2 O3 , UO2 and ThO2 concentrations. The Zashikhinsky deposit was derived from the magma of “transitional composition”, bearing mineral associations intermediate between associations of agpaite and Li-F granites. Acknowledgments. This study was supported by RFBR, research project no. 20-05-00261, Integration project of ISC SB RAS (block 1.4), Governmental assignment for Project no. 0284-2021-0008.

References Alymova, N.V., Vladykin, N.V.: Features of the composition of ore-forming minerals in raremetal alkaline granites of the Zashikhinsky massif (Irkutsk region). Notes of the Russian Mineralogical Society 1, 76–91 (2021) Arhangel’skaya, V.V., Ryabcev, V.V., Shuriga, T.N.: Geological structure and mineralogy of the tantalum deposits of Russia. Mineral Raw Mater. 26, 155–189 (2012) Arhangel’skaya, V.V., Shuriga, T.N.: Geological features, zoning, and mineralization of the Zashikhinsky tantalum-niobium deposit. Domestic Geol. 5, 7–10 (1997) Beskin, C.M.: Geology and Indicator Geochemistry of Tantalum-Niobium Deposits in Russia (Rare-Metal Granites), p. 112. Scientific World, Moscow (2014) Dergachev, V.B., Annikova, I.Yu.: Ongonite-like dikes of the Zashikhinsky rare metal deposit (Eastern Sayan). Doklady Akademii Nauk 332(5), 614–616 (1993) Frost, C.D., Frost, B.R.: On ferroan (A-type) granitoids: their compositional variability and modes of origin. J. Petrol. 52, 39–55 (2011) Geochemistry, mineralogy and genetic types of deposits of rare elements. In: Vlasov, K.A. (ed.) Genetic Types of Deposits of Rare Elements, vol. 3, 860 p. Science (1966) Kovalenko, V.I.: Petrology and Geochemistry of Rare-Metal Granites, p. 205. Nauka Publ., Novosibirsk (1977)

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Kovalenko, V.I., Kovalenko, N.I.: Ongonites are Subvolcanic Analogs of Metal Li-F Granites, p. 127. Science, Moscow (1976) Kudrin, V.S., Shuriga, T.N.: Russian experience in discovering unique and large complex raremetal (Ta, Nb, Y, TR, Zr) deposits in alkaline quartz-albite-microcline metasomatites and ways of its implementation in modern conditions. In: Large and Unique Deposits of Rare and Noble Metals, pp. 79–84. Publishing House of the Mining Institute, St. Petersburg (1998) Lufuandi Matondo, I.P., Ivanov, M.A.: Composition and probable root source of columbite from alluvial deposits of the Mayuko region (Republic of the Congo). Notes of the Mining Institute 242, 139–149 (2020) Maniar, P.D., Piccoli, P.M.: Tectonic discrimination of granitoids. GSA Bulletin. 101(5), 635–643 (1989) Mashkovcev, G.A., Bykhovskij, L.Z., Rogozhin, A.A., Temnov, A.V.: Prospects of rational development of complex niobium-tantalum-rare-metal deposits of Russia. Explor. Prot. Miner. Resour. 6, 9–13 (2011) Vladykin, N.V.: Mineralogical and Geochemical Features of Rare-Metal Granitoids in Mongolia, p. 200. Science, Novosibirsk (1983) Vladykin, N.V., Alymova, N.V., Perf il’ev, V.V.: Geochemical features of rare-metal granites of the Zashikhinsky Massif, East Sayan. Petrology 24(5), 512–525 (2016) Whalen, J.B., Currie, K.L., Chappell, B.W.: A-type granites: geochemical, characteristics, discrimination and petrogenesis. Contrib. Mineral. Petrol. 95, 407–419 (1987) Yarmolyuk, V.V., Kozlovsky, A.M., Nikiforov, A.V., Travin. A.V., Lykhin, D.A.: Composition, sources, and mechanisms of origin of rare-metal granitoids in the Late Paleozoic Eastern Sayan zone of alkaline magmatism: a case study of the Ulaan Tolgoi massif. Petrology 24(5), 477–496 (2016) Yarmolyuk, V.V., Kuz’min, M.I.: Late Paleozoic and Early Mesozoic rare-earth magmatism of Central Asia: stages, regions and conditions of formation. Geol. Ore Deposits 54(5), 375–399 (2012)

The Inclusions in Zircon of the Kozhim Massif (The Subpolar Urals) Yu. V. Denisova(B) Institute of Geology, FRC Komi SC UB RAS, Syktyvkar Branch of the Russian Mineralogical Society, Syktyvkar, Russia [email protected]

Abstract. The study of zircon provides extensive information of a geological and petrographic nature. A detailed study of the inclusions of this mineral is even more able to supplement the data obtained. In the present paper, the mineral inclusions from the accessory zircon of the Kozhim granite massif (the Subpolar Urals) are considered. These minerals usually contain a large amount of the fluid and molten inclusions. Mineral varieties are represented by inclusions of apatite, quartz, plagioclase, titanite, monazite, epidote. For the first time, the gold inclusions were detected. Apatite can be divided into early and late generations of the host mineral. Monazite clearly indicates the zircons crystallized at the final stage of granitogenesis. Quartz and, more rarely, plagioclase prefer to fill the cracks of zircon after exposure to catalase processes. Even a single gold piece indicates the presence of gold in the parent melt. Titanite and epidote can be considered as indicators of secondary generation zircons. Keywords: Zicron · The inclusions · Granite · The Kozim massif · The Subpolar Urals

1 Introduction Zircon is characterized by exceptional resistance to various chemical and physical influences occurring in this environment. Due to this stability, the mineral is extremely popular for obtaining various geological and petrological information, including as a geochronometer and geothermometer. At present, the level of modern equipment allows us to obtain information not only about the morphological and chemical features of accessory zircon, but also about the inclusions determined in this accessory. The study of zircon inclusions can provide data on the phase composition, chemistry, temperature and pressure of the mineral-forming medium, divide the zircons into early and late generations, determine whether it is pre-deposited, re-deposited or formed initially during the formation of the rock, etc. (Lyakhovich 1979; Krasnobaev 1986; Nosyrev et al. 1989; Guo et al. 1996). This paper presents the results of the study of inclusions in the accessory zircon of the Kozhim granite massif (the Subpolar Urals). Several granite massifs are exposed in the vaulted part of the Lyapinsky anticlinorium. One of them is the Kozhim massif (Fig. 1.). This massif is the second in area © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 149–155, 2023. https://doi.org/10.1007/978-3-031-23390-6_20

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among the bodies that make up the Kozhim interplastic intrusion, which breaks through the deposits of the Puivinsky formation of the Middle Riphean. The Kuzpuayu granite massif is also part of this intrusion. The Kozhim massif is considered to be a group of isolated elongated plast-like bodies located on the banks of the Kozhim River in the basins of the Ponyu, Oseyu and Epkoshor streams. The rocks of the massif are highly fragmented and shale formations. In some places, the Kozhim granites have been transformed into sericite dynamometamorphic shales. The granites of this massif with the greatest preservation of the primary structure and appearance are dense gneiss-like rocks. These rocks are characterized by a pink color, reflecting the increased content of alkaline feldspar in the rock, and a greenish-gray shade, indicating the presence of muscovite, small grains of quartz in granite. Macroscopic examination of the rock reveals large subidiomorphic feldspars embedded in a medium-fine-grained mass consisting of quartz grains, feldspars, and mica flakes. This allows us to speak about the granular hypidiomorphic structure of the Kozhim granites. In some places, the structure of the studied rocks turns into medium-grained allotriomorphic. Rock-forming minerals are represented by potassium-sodium feldspar (up to 50%), plagioclase (up to 20%), quartz (up to 40%), biotite (up to 5%), muscovite (up to 7%). Among the accessory minerals, the most common are zircon, apatite, and garnet. Titanite, ortite, fluorite, monazite, and torite can also be observed in the samples (Fishman et al. 1968; Makhlaev 1966).

Fig. 1. Overview map of the area of the Circumpolar Urals (the rectangle marks the area of study) (Pystin and Pystina 2008). 1 – isinglass - quartz shales, green ortoshales, quartzite; 2 – isinglass - quartz shales, porphyries, porphyrites, interlayers of marbles and quartzites; 3 – granites; 4 – gabbro; 5 – the geological boundaries: stratigraphic and igneous, b – tectonic; 6 – the occurrence of planar structures. The massifs (numerals in circles): 1 – the Kuzpuayu massif; 2 – the Kozhim massif.

2 Materials and Methods Accessory zircon in the rocks of the Kozhimsky granite massif is mainly represented by well-cut light yellow transparent crystals of a dipyramidal-prismatic appearance. The grain size ranges from 0.05 to 0.15 mm with an elongation coefficient of 1.0 to 1.8. The faces (100) and (110) are developed. (111) dipyramide is present. Some crystals

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contain inclusions of quartz, apatite, plagioclase, monazite, titanite, and epidote. The content of zircons leaves 80% of the total volume of the mineral in the rock. In a small amount (in total, no more than 20% of the total composition of the mineral content in the rock), brown, more often translucent dipyramidal-prismatic zircons (size 0.05– 0.10 mm, elongation coefficient 1.0–2.0) and light yellow transparent and translucent dipyramidal-prismatic and prismatic zircons (size 0.4–0.8 mm, elongation coefficient 2.0–4.0 (up to 6.0)) are also noted. The appearance of these types of crystals is due to the development of the faces (100), (110), (111). Dark zircon contains inclusions of apatite, quartz, plagioclase, monazite, and epidote. Gold was found in one grain. In elongated light crystals, quartz, plagioclase, apatite, and epidote formations are common among inclusions (Denisova 2014, 2016).

3 Results and Discussion Kozhimsky crystals of zircons are often overflowing with gas-liquid and solid mineral inclusions. Mineral varieties are mainly represented by inclusions of apatite, quartz. Single grains contain inclusions of plagioclase, titanite, monazite, and epidote. For the first time, the inclusion of gold was observed in one zircon crystal (Fig. 2.).

Fig. 2. The inclusions of apatite (A), quartz (Q), plagioclase (P), titanite (T), monazite (M), epidote (E), and gold (G) in zircon from the granites of the Kozhim massif.

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Apatite is the main inclusion in the studied zircon. Its number is 60% of the total number of other inclusions. The mineral is marked in the form of long-prismatic grains, the section of which has the form of a hexagonal hexagon. Apatite inclusions are observed both in the central part and in the peripheral zone of the zircon crystal. The mineral was most likely captured during the growth of the zircon itself, which indicates an earlier crystallization of apatite compared to the host mineral. According to microprobe data, the mineral belongs to the fluorine variety due to the increased content of fluorine (on average, 2.7 wt.%). The indicator F/Cl ratio (on average 21) indicates the igneous origin of the apatite inclusions. These inclusions are also characterized by an increased iron content (FeO on average 0.48 wt%) (Table 1) (Denisova 2019). Table 1. Chemical composition of inclusions in the zircon of the Kozhimsky massif (wt.%) Oxides

The inclusions in zircon Apatite

Quartz

Plagioclase

Titanite

Monazite

Epidote

SiO2

0,27

99,7

70,52

32,88

0,78

34,01

TiO2

-

-

0,15

33,11

-

0,08

Al2 O3

-

0,22

17,11

7,09

-

27,22

Fe2 O3

-

0,23

0,55

-

-

-

FeO

0,48

-

0,03

0,18

-

9,69

MnO

0,05

-

-

0,03

-

0,27

MgO

0,09

-

0,27

0,04

-

0,09

CaO

53,19

0,15

0,23

24,78

-

23,71

Na2 O

0,05

-

10,62

-

-

-

K2 O

-

-

0,29

0,03

-

-

P2 O3

45,75

-

-

0,07

28,77

-

ThO2

-

-

-

0,33

13,22

-

UO2

-

-

-

0,11

3,3

-

TR2 O3

0.33

-

-

1,06

53,31

5,11

Y2 O3

-

-

-

0,31

0,89

-

F/ Cl 

21

-

-

-

-

-

100,21

100,03

99,77

100,02

100,27

100,18

Quartz is also a common inclusion. Usually, the mineral is found in the marginal zones of zircon crystals in the form of rounded inclusions. According to the microprobe analysis, quartz inclusions contain aluminum impurities (Al2 O3 on average 0.22 wt. %), iron (Fe2 O3 on average 0.23 wt.%). Calcium (CaO on average 0.15 wt. %), Most of the mineral inclusions are epigenetic formations formed as a result of the impact of superimposed processes. Upon completion of crystallization, the zircon was subjected to deformation with the formation of cracks, which were subsequently “healed” by quartz.

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Plagioclase forms rare inclusions in the Kozhim zircons. The mineral forms round inclusions more often in the edge region of the zircon crystal. The chemical composition of plagioclase is represented by albite, which is characterized by an increased content of iron impurities (Fe2 O3 on average 0.55 wt. %), magnesium (MgO on average 0.27 wt. %), potassium (K2 O on average 0.29 wt. %), calcium (CaO on average 0.23 wt.%). This mineral, as well as quartz, can fill the cracks of zircon after the impact of cataclysm processes on it. Titanite in the form of the zircon inclusion is rare. These are small rounded grains confined to the central zones of zircon crystals. The chemical composition of the titanite inclusions is similar to the accessory titanite of the Kozhim massif. Analysis of the microprobe data shows the presence of aluminum impurities (Al2 O3 on average 7.09 wt. %), rare earths (TR2 O3 on average 1.06 wt.%). The formation of the mineral probably occurred simultaneously with zircon. Monazite in the form of the zircon inclusion occurs in single grains. The mineral is located mainly in the peripheral zone of zircon crystals. It is rarely observed in the middle region of zircon crystals. According to the data of microprobe analysis, monazite belongs to the cerium variety with the presence of thorium impurities (ThO2 on average 13.22 wt. %). Monazite was formed simultaneously with the zircon containing it at its final stage of crystallization. Epidote also makes up the rare inclusiveness in studied accessory zircon. It is noted in the marginal parts of zircon crystals mainly in the form of irregular grains. It can also develop along the cracks of deformed zircon. The study of the chemical composition of the epidote revealed an increased content of rare earth elements (TR2 O3 on average 5.11 wt.%). The release of this mineral from the parent melt occurred in the late stage of granitogenesis. Epidote was formed after the complete crystallization of the zircon of the Kozhim massif. Gold was found in the single grain of Kozhim zircon. An earlier study showed that the inclusion consists entirely of Au, without any Ag impurities. The gold inclusions are located in the middle region of the zircon crystal, which allows us to talk about the formation of gold in the process of growth of the zircon itself. It was assumed that a small amount of gold was already present in the mineral-forming medium of this zircon. The research of M. V. Fishman and his colleagues also revealed single signs of native gold in the granites of the Kozhim massif.

4 Conclusions Analysis of the composition of the inclusions in zircon, taking into account the sequence of crystallization of minerals during the formation of the rock, makes it possible to obtain more detailed information about the individual stages of zircon formation (Erokhin et al. 2017). According to the research of M.V. Fishman and his colleagues, zircon was the first to crystallize into the solid phase. Later in the same early magmatic stage, apatite with the bulk of feldspars was distinguished. Monazite was formed in the final stage of this stage. Titanite, epidote, and zircon of secondary generations were formed in the Late Magmatic stage. Having studied the location of the mineral inclusion in the zircon crystal and its composition, it is possible to draw conclusions not only about the early and late varieties

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of zircon, but also about some features of the mineral-forming medium. Apatite is most often found in the central part of zircon crystals. Some inclusions of the phosphate mineral have the perfect cut. These apatite crystals probably formed earlier than the host crystal and were captured by the growing zircon. The presence of fluorapatite in the periphery of zircon crystals indicates the parallel growth of these minerals. The appearance of monazite in zircon may be associated with a sharp jump in the content of rare earths in the melt. Moreover, the crystallization of the zircon-monazite system occurred later than the zircon-apatite system. Quartz inclusions are much more common than plagioclase inclusions. Probably, the period of active separation of quartz from the melt is longer than for plagioclase. The inclusions of titanite and epidote are the marker of secondary generation zircons.

References Denisova, J.V.: Tipomorficheskie i tipohimicheskie osobennosti akcessornyh cirkonov granitoidov pripoljarnogo Urala. Vestnik Instituta geologii Komi NC UrO RAN, Syktyvkar 5, 9–16 (2014). [Denisova JuV. Typomorphic and typochemical accessory zircons sings of the Subpolar Urals granitoids. Vestnik IG Komi SC UB RAS, Syktyvkar;2014;5:9–16. (In Russ.)] Denisova, J.V.: Termometrija cirkona iz granitoidov Pripoljarnogo Urala. Vestnik Instituta geologii Komi NC UrO RAN, Syktyvkar 11, 11–22 (2016). [Denisova JuV. Temperature survey of zircon from the granitoids of the Subpolar Urals. Vestnik IG Komi SC UB RAS, Syktyvkar;2016;11:11–22. (In Russ.)] Denisova, J.V.: Termometriya nasyshcheniya cirkona, apatita, monacita (Kozhimskij massiv, Pripolyarnyj Ural). Izvestiya Komi nauchnogo centra UrO RAN, Syktyvkar 3, 25–30 (2019). https://doi.org/10.19110/1994-5655-2019-3-47-52. [Denisova YuV. Thermometry of saturation of zircon, apatite, monazite (the Kozhim massif, the Subpolar Urals). Proceedinds Komi SC UB RAS, Syktyvkar;2019;3:25-30. doi https://doi.org/10.19110/1994-5655-2019-3-47-52. (In Russ.)] Erohin, Y.V., Ivanov, K.S., Koroteev, V.A., Hiller, V.V.: Mineralogiya vklyuchenij i vozrast cirkona iz granitov fundamenta Verhnerechenskoj ploshchadi (Poluostrov YAmal). Litosfera 17(6), 81–90 (2017). https://doi.org/10.24930/1681-9004-2017-6-081-090. [Erokhin Yu.V., Ivanov K.S., Koroteev V.A., Khiller V.V. Mineralogy of the inclusions and age of zircon from granite basement of Verkhnerechensk area (Yamal peninsula). Lithosphere. 2017;17(6):81–90. (In Russ.) https://doi.org/10.24930/1681-9004-2017-6-081-090] Fishman, M.V., Jushkin, N.P., Goldin, B.A., Kalinin, E.P.: Mineralogija, tipomorfizm i genezis akcessornyh mineralov izverzhennyh porod severa Urala i Timana. M.- L: Nauka (1968). [Fishman MV., Jushkin NP., Goldin BA., Kalinin EP. Mineralogy, typomorphism and Genesis of accessory minerals of igneous rocks of the North Urals and Timan. M.- L.: Nauka;1968. (In Russ.)] Guo, J., O’Reilly, S.Y., Griffin, W.L.: Zircon inclusions in corundum megacrysts: I. Trace element geochemistry and clues to the origin of corundum megacrysts in alkali basalts. Geochim. Cosmochim. Acta 60, 2347–2363 (1996) Krasnobaev, A.A.: Cirkon kak indikator geologicheskihz processov. M.: Nauka (1986). [Krasnobaev AA. Zircon as an indicator of geological processes. M.: Nauka;1986. (In Russ.)] Lyahovich, V.V.: Akcessornye mineraly gornyh porod. M.: Nedra (1979). [Lyakhovich V. V. Accessory minerals of rocks. M.: Nedra, 1979. (In Russ.)] Mahlaev, L.V.: Granitoidy severa Central’no- Ural’skogo podnjatija (Poljarnyj i Pripoljarnyj Ural). Ekaterinburg: UrO RAN (1996). [Mahlaev LV. Granitoids of the North of the Central Ural uplift (the Polar and the Subpolar Urals). Ekaterinburg: UrO RAN;1996. (In Russ.)]

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Nosyrev, I.V., Esipchuk, K.E., Orsa, V.I., Robul, V.M.: Generacionnyj analiz akcessornogo cirkona. M.: Nauka (1989). [Nosyrev IV., Esipchuk KE., Orsa VI., Robul VM. Generational analysis of accessory zircon. M.: Nauka, 1989. (In Russ.)] Pystin, A.M., Pystina, J.I.: Metamorfizm i granitoobrazovanie v proterozojsko- rannepaleozojskoj istorii formirovanija Pripoljarnoural’skogo segmenta zemnoj kory. Litosfera 11, 25–38 (2008). [Pystin AM., Pystina JuI. Metamorphism and granite formation in the Proterozoic-early Paleozoic history of the formation of the Circumpolar segment of the earth’s crust. Litosfera. 2008;11:25–38. (In Russ.)]

Method for Multiple Analysis of Indicator Mineral Compositions of Kimblites to Estimate the Presence of Type IIa Large Diamonds A. S. Ivanov1(B) and V. N. Zinchenko2 1 Saint-Petersburg Branch of the Russian Mineralogical Society, Saint-Petersburg Mining

University, Saint-Petersburg, Russia [email protected] 2 Catoca Mining Company Catoca, Luanda, Angola

Abstract. In the last decade, researchers are especially interested in giant type IIa diamonds, which differ strongly in composition and physical characteristics from diamonds of “P” and “E” generations. Especially large diamonds of this type of high quality are mined at several deposits in Africa and Russia. The cost of some crystals of such diamonds reaches tens of millions of dollars (Fig. 1). Their genesis has not yet been fully elucidated, and it represents a large field for the study of this amazing phenomenon of kimberlite nature. One of the ways to decrypt the genesis of these diamonds is to simulate the mineralogical and geochemical conditions of the diamond generation environment by the chemical compositions of the KIM that characterize this environment - pyropes, chromites, ilmenites and pyroxenes. 5E diagrams of the KIM compositions for five elements - Cr, Al, Fe, Mg, Mn were constructed for Karove and Grib industrial deposits, mainly containing large and giant type of diamonds. On the basis of such diagrams, a method for assessing the probability of the presence of large and giant type IIa diamonds in kimberlites of explored deposits is proposed based on the method of comparison with the standard (analogy method). Keywords: Kimberlite indicator minerals (KIM) · Cluster groups (CG) · Chemical genetic groups (CGG) · Type IIa diamonds · Carat (ct) · Kimberlite · Pipe

1 Introduction A quantitative assessment of the diamond content of kimberlites (diamond content in ores) based on geostatistical methods encounters an insurmountable “nugget” effect limiting the continuity of the distribution law of diamond crystals by weight within 2–2.5 carats (exponential, power-series distribution) (Zuev, 2005; Zinchenko, 2017). Statistical methods and models do not take into account the presence of rare, large, more than 10.9 ct. diamonds, and giant diamonds weighing more than 100 carats in kimberlites. It reduces the accuracy and quality of the geological and economic assessment of such deposits, which often have low average diamond grades in ores (0, 14 ct/t - Karove © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 156–164, 2023. https://doi.org/10.1007/978-3-031-23390-6_21

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pipe, Botswana). The authors proposed a method for predicting the presence of large and giant type IIa diamonds in kimberlites based on the compositions of four KIM pyropes, chromites, picroilmenites, and pyroxenes on the diagrams of five elements (Cr, Al, Fe, Mg, Mn) - 5E diagrams (Zinchenko, Ivanov 2021; Ivanov, Zinchenko, 2021). According to Moore (2009), isotopically light, nitrogen-free, non-UV-fluorescent giant diamonds of type IIa from kimberlites are a generation close to the websterite upper mantle paragenesis (“W”) associated with proto-kimberlite melt. The opposite hypothesis of deep mantle generation of type IIa diamonds is put forward by Schmit et al. - crystallization in the “pockets” of the Fe–Ni melt at depths of more than 250 km. It is based on the study of the composition of drop-shaped spherical microinclusions in fractures in type IIa diamonds (Smith et al. 2016). Both of these hypotheses will be considered and the author’s concept of ontogeny of type IIa giant diamonds and the characteristics of their generation environment will be proposed below.

Fig. 1. Type IIa giant diamonds: crystal of irregular shape weighing 127.34 ct., Grib mine, Russia (a); crystal of irregular shape, 910 ct., 40 million USD, Letseng mine, Lesotho (b); crystal with fragments of octahedron faces, 1109 ct., 53 million USD, Letseng mine (c); crystal of irregular shape with flat chips, 404 ct., Lulo mine, Angola (Zinchenko, Ivanov, 2021).

2 Research Methods and Materials Chemical and mineralogical modeling of the environ for the generation of IIa diamonds is implemented on the basis of data on the chemical composition of KIM, obtained by

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RXS analysis on a JX-8230 microprobe, complete with a software product that allows simultaneous determination of the composition of both main and impurity elements by two types of spectrometers - WDS and EDS. The calculations by the method of cluster group analysis involved the results of microprobe analysis of the compositions of more than 10,000 KIM grains from the Karove and V.I. Mushroom. Clustering of the analytical database for CG compositions was carried out according to the author’s algorithms (Ivanov, 2016) based on the well-known Dawson-Stephens classifications for pyropes (Dawson, Stephens, 1975) and V.K. Garanina for picroilmenite, chrome-diopside, and chrome spinel (Garanin et al. 1991). For these two deposits, containing especially large and giant diamonds (Fig. 1), diagrams of the compositions of the KIM for Cr, Al, Fe, Mg were plotted. This type of diagram was proposed by Mitchell R. (Mitchell, 1986) for the compositions of chromites, which was applied by the authors to the compositions of picroilmenites, pyropes and pyroxenes. The concentration of the fifth element - Mn - is shown by the size of a spherical analytical “point”, which forms a bubble diagram (Fig. 2) (Ivanov, 2020). For better perception, the diagrams show different KIMs in different colors, as well as the corresponding trend lines of changes in their compositions. By the number of chemical elements involved in the analysis, this type of graphs was named 5E diagrams. They are supplemented by the correlation table of the frequency of occurrence (FO) of the CG KIM, which demonstrates their high correlation (Table 1). The KG IMK are believed to be indicative of such combinations, which capture the mineralogical and geochemical environment/melt conditions at close or equal values of their ChV in reference kimberlites with type IIa diamonds (Zinchenko, Ivanov, 2021).

3 Research Results 5E diagrams for Karove and Grib industrial deposits, containing large and giant diamonds of high gem quality, are presented (Fig. 2). The charts show a high degree of identity of the presented compositions of KIM, which indicates the similarity of the geochemical environments of the formation of their parasteresis in the area of generation of these diamonds at the level of the mantle producing kimberlite melts. The diagrams are formed according to a common database and give an idea of the integral parasteresis contour of the CG (CGG) of the KIM compositions of the reference Karove pipe (more than 10 000 analyzes), shown by the dotted line. Genetic affiliation of indicator for large diamonds CG (CGG) KIM according to V.K. Garanin (Garanin et al. 1991) and Dawson D. (Dawson et al. 1975), noted in Table 1 is shown in Fig. 2. Noteworthy is the CG of pyropes G2, established by A. Moore in inclusions in giant diamonds from the Karove pipe (Moore, 2009). This fact proves the paragenetic connection of giant type IIa diamonds with the CG G2 of pyropes, which makes it possible to use its parasteresis with the CG (CGG) of other KIMs to construct a mineralogical-geochemical model of the generation environment for such diamonds. It is significant that the NWs of this indicator CG of pyropes in Karove and Grib tubes are the same (Table 1). Based on the convergence of the values of the CG FO (CGG) of the KIM series in both tubes, their pairs were selected that have equal or similar values, which are marked in yellow in Table 1. The following pairs of CG (CGG) KIMs have the closest FO values: chromespinelide shp1 and shp9;

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pyropes G1, G2, G3 and G10; picroilmenites ilm4; chrome-diopside CrDi7 - they are considered indicators of the presence of giant type IIa diamonds in kimberlites.

Fig. 2. Compositions of KIM of Karove kimberlite pipes and Grib mine on 5E diagrams Fe/(Fe + Mg) – Cr/(Cr + Al): dotted contour - area of KIM compositions of the reference Karove pipe (more than 10 000 analyzes); blue lines - picrite (horizontal), - kimberlite (vertical) trends in chromite compositions (blue numbers - CGG chromites by V.K. Garanina); black lines - paramagnetic (right) and ferrimagnetic (left) trends in picroilmenite compositions (black numbers CGG ilmenites by V.K. Garanina); red lines - trends in the compositions of chromium pyropes G10 (left), titanium uvarovite-pyropes G11 (right) (red numbers - KG of Dawson’s pyropes); $500 and $1000 - the cost of diamonds USD/ct. (https: // www. interfax.ru/business/563835, ECONOMY; https://www.rough-polished.com/ru/analytics/111699.html); concentration of Mn reflected by a spherical “bubble” corresponding to the composition of the KIM; CGG of chromespinelide: Shp1 - from high-diamond-bearing dunites and harzburgites and inclusions in diamonds; Shp9 - from magnesium-calcium alcremites; CG pyropes: G1 - titanium pyropes of kimberlites, lherzolites and websterites; 3.33% grains with diamonds; MgO (20%), TiO2 (0.58%), Cr2 O3 (1.34%); G2 - high-Ti pyropes of kimberlites; inclusion in large and giant diamonds of the weakly diamondiferous kimberlite Karove (Moore, 2009); G3 - calcium pyrope-almandines of kimberlites, lherzolites, eclogites and websterites; with diamonds 46.15% of grains; high contents of FeO and CaO (16.49% and 6.5%, respectively), MgO (13.35%), TiO2 (0.31%) and Cr2 O3 (0.30%); G9 - chromium pyropes of kimberlites, lherzolites, harzburgites, eclogites and websterites, 5.17% were found with diamonds; TiO2 , CaO (0.17%; 5.17%;), Cr2 O3 (3.5%); G10 - low-calcium chromium pyropes of kimberlites and garnet serpentinites, 41.56% with diamonds; MgO (23.2%), Cr2 O3 (7.7%) and CaO (2.13%); CGG of picroilmenites: Ilm3 - from inclusions in diamond, chromium-containing (0–5.4% Cr2 O3 , on average 1.7%), high-Mg; from non-diamondiferous peridontitis and cataclastic lherzolites; Ilm4 - high-chromium (0.8–7.3% Cr2 O3 , on average 2.0%) high-magnesian hemoilmenite from non-diamondiferous peridotites and ilmenite-orthopyroxene rocks (enstatitites); Chrome-diopside CGG: CrDi1 - inclusion in diamonds, jadeite-yuriite-clinoferrisilite-clinoenstatite-diopside; CrDi4 - intergrowths with diamond, aegirine-yuriite-jadeite-diopside; CrDi7 - non-diamondiferous lherzolites, yuriite-clinoferrisiliteclinoenstatite-diopside; CrDi9 - weakly diamondiferous ilmenite lherzolites, websterites and pyroxenites, yuriite-jadeite-clinoferrisilite-clinoenstatite-diopside (Zinchenko and Ivanov, 2021).

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Table 1. Frequencies of CG (CGG) KIMs of Karove kimberlite pipes and Grib mine with indicators for the content of type IIa giant diamonds by parasteresis (genetic belonging of KIMs in Fig. 2) (Zinchenko, Ivanov, 2021).

Notably, the limits of Cr/(Cr + Al) ratio variation controlling PT environmental parameters, of the environ, in chrome-diopside and picroilmenites in chromediopsides and picrolmenites are broad (0.1–1.0) and almost identical, the latter close to the paramagnetic trend. On the contrary, in the chromospinelids they are rather narrow (0.8–1.0), with a pronounced pycritic trend. The Fe/(Fe + Mg) ratio for all four MSA as a whole has rather wide variation limits (0.1–0.7), but for separate CG of chromediopsides, chromospinels and picrolmenites its variation limits are within a local interval (0.1–0.2); pyrope is distinguished by wider range of variations (0.1–0.6) and they are represented by contrast in genetic belonging CG - from websterite-eclogite paragenesis to peridotite-dunite and lherzolite. The paramagnetic low-hematite picrolmenites, which are indicative of the low oxidation potential of KG ilm1,2, are practically not represented in the Karove pipe, characterized by low gross diamond content − 0.14 ct, whereas in the Griba pipe their CH is 40%, determining its high diamond content − 0.30–0.50 ct for the crater blocks and 1.0 ct for the diatremite ore blocks. Griba pipe has a NiF of over 40%, which determines its higher diamondiferousness − 0.30–0.50 ct for the crater blocks and over 1.0 ct for the diatreme ore blocks (https://www. interfax.ru/business/563835, ECONOMICS; https://www. rough-polished. com/en/analytics/ 111,699.html). The effectiveness of the 5E diagram method is demonstrated using two Yakutian kimberlite diamond deposits as examples (Fig. 3). The diamond content in kimberlites from the Aikhal pipe is several times higher than in the Komsomolskaya pipe, but the

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cost of diamond crystals from the latter is 7 times higher ($500/car) than from the Aikhal pipe ($70/car). A distinctive feature of the compositions of the of the IMC pipe Komsomolskaya, as well as of the Griba and Karove kimberlite pipes, is the presence of diamondiferous websterite parageneses of chromites and pyrope, corresponding to areas with elevated chromium and iron values (high PT parameters of the streams). The kimberlite of the Aikhal pipe is characterized by a higher degree of metasomatism, which is fixed on the diagram by a trend of more ferruginous composition of picrolmenites high Fe2 O3 content (high oxidative potential of the medium), which affects the quality of its diamonds.

Fig. 3. Compositions of KIM of diamondiferous kimberlite pipes Komsomolskaya and Aikhal on the diagram Fe/(Fe + Mg) – Cr/(Cr + Al) in the contour of compositions of KIM of the reference Karove pipe (Symbols in Fig. 2; compositions of chrome-diopside - calculated parasteresis) (Ivanov, Zinchenko, 2021).

4 The Discussion of the Results The presented data on the compositions of KIMs for kimberlites containing type IIa giant diamonds made it possible to propose a physicochemical model of the environment of their formation, synthesizing the two aforementioned hypotheses - “upper mantle” websterite (Moore, 2009) and peridotite “deep” (Smith et al. 2016). The compositions of the CG (CGG) KIMs, indicative of large type IIa diamonds, show their hybrid nature, which may be associated with the gradual transformation of the composition of the environ of their generation at the intratelluric stage (Milashev, 1994) of the development of the kimberlite volcanic process (Zinchenko and Ivanov, 2021). It seems that the more highly parametric proto-kimberlite melts in the plume circulation mode rose to the upper mantle level, where they interacted with its eclogite layer. This interaction led to the melting of ore minerals of eclogites and the segregation of metal-oxide-sulfide melts in the process of segregation, collapsing into droplets, the coalescence of which led to the formation of “pockets” described by Schmitt (Smith et al.

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2016). We recorded this process in eclogite xenoliths of the Katoka pipe, in which molten drops of metal-oxide-sulfide composition were revealed (Fig. 4) (Zinchenko, 2016). It is significant that the spherical Fe,Ni (C,S) inclusions in type IIa giant diamonds described by Schmitt (Smith et al. 2016) are close in composition to Fe,Ni (O,S) spheroids from eclogites, which indicates a single source and mechanism of their formation as a result of partial melting of oxide-sulfide minerals of mantle rocks. The absence of carbon in their composition is most likely the effect of the deposition of a graphite layer on the surface of the eclogite sample during the RXS analysis on a microprobe. The characteristic curvilinear internal zoning of spheroid grains in eclogites is evidence in favor of the hypothesis of differentiation of the mantle substrate by the “zone melting” mechanism (Fig. 4, e, f) (Milashev, 1994). It took place in the PT conditions of equilibrium of the Py-Cpx mineral association in eclogites - T = 1000–1300 °C, P = 42–70 Kbar (diamond depth facies) (Korolev et al. 2014).

Fig. 4. Grains of Fe,Ni (O,S) phases in eclogites from kimberlites of the Katoka pipe: grain rounded as a result of fusion, sample Kat-1, thin section with rectangular field of view “b”, NII (a); detail of thin section “a” with rounded grain, KIM photo (b); grain “b” with points of microprobe analysis, KIM photo (c); spherical grains of Fe,Ni (O,S) molten phases in clinopyroxene (Cpx), sample Kat-5 - surface of a thin section with a highlighted field “d”, NII (d); detail of thin section “g”, KIM photo (e); elliptical Fe,Ni (O,S) spheroid in pyrope (Py) grain, sample Kat-15, KIM photo (e). Microprobe JSM-6510 LA with JED-2200 (JEOL) (Zinchenko, 2016).

5 Conclusions The proposed method is based on a comprehensive assessment of KIM compositions by constructing 5E diagrams using group cluster analysis procedures. Diagram 5E makes it possible to assess the presence of expensive and large type IIa diamonds in kimberlite pipes at the geological exploration stage, as well as to reconstruct the composition of deep mantle rocks, which is reflected in the compositions of the KIM when they are graphically represented by five chemical elements.

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According to the composition of the KIM of Karove pipes and Grib mine, geochemical signs of the presence of especially large type IIa diamond crystals in kimberlites (“W” generation, according to (Moore, 2009) were established - the same or close values of the FO CG KIM, which are highlighted in yellow in Table 1 and whose compositions on the 5E diagrams fall into contour of the KIM compositions of the reference Karove pipe (Fig. 3). The compositions of KIMs indicative of large type IIa diamonds show their hybrid nature, which may be associated with the introduction of deep ultrabasic melt into the upper mantle eclogites (websterites, alcremites, and pyroxenites) in the plume circulation regime. This confirms Moore’s hypothesis about the crystallization of type IIa giant diamonds in proto-kimberlite melt within the upper mantle (eclogite-websterite paragenesis, “W” generation) (Moore, 2009). Microspherical Fe,Ni (C,S) drop-shaped inclusions in type IIa giant diamonds described by E. Schmitt are close in composition to Fe,Ni (O,S) spheroids from eclogites (Zinchenko et al. 2016), which indicates a single source and mechanism of their formation as a result of the melting of oxide-sulfide minerals of eclogites by the mechanism of “zone melting” (Milashev, 1994) at T = 1000–1300 °C and P = 42–70 Kbar (diamond depth facies) (Korolev et al. 2014), and which confirms the hypothesis of E. Schmitt about the crystallization of such diamonds in metal-sulfide-oxide melts (“pockets”) (Smith et al. 2016). Indicator CG (CGG) KIMs established in the reference Karove kimberlite pipe with very large and giant type IIa diamonds can be used to predict their presence in kimberlites by the method of analogy and comparison with the standard in prospecting and exploration of such deposits in perspective regions of kimberlite provinces of the world.

References Diamond mining industry in Botswana - current state and prospects (2018). https://www.roughpolished.com/ru/analytics/111699.html Garanin, V.K., Kudryavtseva, G.P., Marfunin, A.S., et al.: Inclusions in diamond and diamondiferous rocks, p. 240. M. Publishing house of Moscow State University (1991) Zinchenko, V.N.: Deposits of diamonds from kimberlites in northeastern Angola, p. 465. Publishing house of St. Petersburg State University (2017) Zinchenko, V.N., Ivanov, A.S.: Modeling of physical and geochemical parameters of crystallization of large type IIa diamonds by parasteresis of their satellite minerals. J. Sci. Lyon, 1(17), 9–14 (2021) Zuev, 2005.Zuev, V.M.: On the role of studying kimberlite ore bodies in the development of domestic diamond geology. Reg. Geol. Metallogenia. No. 26, 34–36 (2005) Ivanov, A.S.: Methodology for calculating mineral parasteresis in kimberlites. In: Proceedings of the XIII All-Russian (with international participation) Scientific school “Mathematical research in natural sciences”, pp. 173–182. Apatity (2016) Ivanov, A.S.: Bubble diagrams of pyrope compositions. In: Collection: Geology and Mineral Resources of North-East Russia: Materials of the X All-Russian Scientific-Practical Conference with International Participation, pp. 343–346 Yakutsk. NEFU Publishing House (2020) Korolev, N.M., Marine, Yu., B., Nikitina LP, et al. High-niobium rutile from upper mantle eclogite xenoliths of the diamondiferous kimberlite pipe Katoka, Angola // Dokl, vol. 454(2), pp. 207– 210 (2014)

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LUKOIL completed the sale of its diamond business to Otkritie for $1.45 billion. https: // www. interfax.ru/business/563835 ECONOMY. 13:44 (2017) Milashev, V.A.: Environment and processes of formation of natural diamonds. “Bosom”. S-Pb, p. 142 (1994) Dawson, J.B., Stephens, W.E.: Statistical classification of garnets from kimberlites and xenoliths. J. Geol. 83(5), 589–607 (1975) Ivanov, A.S.: Statistical analysis of indicator minerals of kimberlites. In: Proceedings of the XIII All-Russian (with International Participation) Fersman Session. KSC RAS. Apatity, pp. 172– 181 (2017) Ivanov, A.S., Zinchenko, V.N.: Method of complex analyzes of the compositions of kimberlite indicator minerals to assess the presence of large diamonds. In: Proceedings of the EGU General Assembly, pp. 22–27. EGU21–1907 (2021) Mitchell, R.H.: Kimberlites: Mineralogy, Geochemistry and Petrology, p. 442. Plenum Press, New York. (1986) Moore, A.E.: Type II diamonds: flamboyant megacrysts // S. Afr. J. Geol. 112, 23–38 (2009) Smith, E.M., et al.: Large gem diamonds from metallic liquid in Earth’s deep mantle. Science in press, vol. 354, pp. 1403–1405.6318 (2016) Zinchenko, V.N.: [Fe, Ni, Cu] (O, S) spheroides from Catoca kimbertits eclogite xenolites. In: 35th International Geological Congress Abstracts. Cape Town. South Africa (2016)

Mineral Inclusions in Irghizites and Microirghizites (Zhamanshin Astroblem, Kazakhstan) E. S. Sergienko1 , S. J. Janson1(B) , A. Esau4,5 , Hamann4 , F. Kaufmann4 , L. Hecht4,5 , V. V. Karpinsky1 , E. V. Petrova3 , and P. V. Kharitonskii2 1 Saint-Petersburg Branch of the Russian Mineralogical Society, Saint-Petersburg State

University, Saint-Petersburg, Russia [email protected] 2 Saint-Petersburg Electrotechnical University ‘LETI’, Saint-Petersburg, Russia 3 Institute of Physics and Technology, Ural Federal University, Ekaterinburg, Russia 4 Museum Für Naturkunde, Berlin, Germany 5 Institut für Geologische Wissenschaften, Freie Universität Berlin (FUB), Berlin, Germany

Abstract. A collection of irghizites and microirghizites selected by the authors during two field seasons 2018–2019 at the Zhamanshin impact structure (Kazakhstan) was studied. The main task is to identify and study mineral inclusions regarding the morphological features of the samples. This study will help to resolve existing ambiguities and contradictions in the data on these impact rocks. On the other hand, it will serve to understand the genesis and ontogenesis of the impact glasses (i.e., zhamanshinites, irghizites, and microirghizites) of the Zhamanshin astrobleme in general and will provide information for the reconstruction of the impact event. Keywords: Zhamanshin · Impactites · Irghizite · Microirghizite · Astrobleme · Impact structure

1 Introduction Zhamanshin is one of the youngest (0.91 ± 0.14 Ma, Schmieder et al. 2020) and wellpreserved astroblems. It is located about 40 km southwest of the village Irgiz on the river of the same name in the southern part of the Turgai plateau. The plateau is a clay semi-desert with a leveled relief, complicated by denudation mountain with a height of 50–100 m. Analysis of geomorphological, geological and geophysical data showed that the target of the Zhamanshin crater has a complex geological structure (Boyko et al. 2009). Impactites (according to the classification of Stöffler et al. 2007) in the Zhamanshin astroblem are represented by a wide range of rocks—glassy melt impact rocks (irghizites, microirghizites), melt impact rocks (massive melts—tagamites and “bombs”—zhamanshinites), zuvite breccias. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 165–177, 2023. https://doi.org/10.1007/978-3-031-23390-6_22

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Interest in the study of irghizites and microirghizites has not faded away since the discovery of the astrobleme in the 1970s, and still. There are uncertainties and contradictions in questions of their genesis, composition, and features of education. The first investigators of the crater showed (Florenskii and Dabizha 1980) that irghizites are confined to the thickness of the allogeneic breccia and are localized in its upper part. They are distributed unevenly (mainly on the slopes of the outer funnel of the crater) and discretely along the radii (which makes it possible to assume the jet character of the melt ejections). They are mainly localized in the narrow southwestern sector of the crater. This point of view is still the most common in publications. However, when drilling deep (up to 1000 m) wells, slags and glass (small fragments, spherules (microirghizites), drop-shaped and dumbbell-like particles—irghizites), similar to nearsurface ones, were encountered at depths of up to hundreds of meters (Masaitis et al., 1990). It is widely believed in the literature that irghizites constitute a chemically homogeneous group with an insignificant spread in the contents of majorelements (for example, the SiO2 content is in the range from 70 to 79 wt%) (Florenskij 1977; Bouška et al. 1981; Izokh 1986; Koeberl 1986; Zolensky, Koeberl 1991). Another feature is the complete absence of mineral inclusions (Florenskij and DikovYu 1981; Skublov and Tyugai 2004; Mizera et al. 2012) and their greater homogeneity compared to other impact melts of Zhamanshin (Schulz et al. 2020). At the same time, it has been shown that at the nanoscale level, irghizites contain numerous inclusions (Gornostaeva et al. (2016). They also contain micron and submicron crystallites of iron oxides (Sergienko et al. 2019). Microirghizites are identical in composition to irghizites (Skublov et al. 2005) or close to them (Glass et al., 1983), but show a lower average SiO2 level and a high nickel content, including in the form of microinclusions (Ni-Fe spherulesand Ni-containing magnetite). The presence of cosmogenic components in the composition of impact glasses from the Zhamanshin crater is beyond doubt. The published data are based on the analysis of the content of trace elements, isotopic studies, and rare finds of intermetallic compounds (for example, iron-nickel spherules in microirghizites). The range of ideas about the type of meteorite is very large. From stone (Florenskii and Dabizha 1980), iron (Taylor and McLennan 1979) and meteorite of chondrite composition (Palme et al. 1978; Bouška et al. 1981; Glass et al. 1983; Jonášová et al. 2016; Mizera et al. 2012; Magna et al. 2017; Vetviˆcka et al. 2010) to the cometary body (Isoh, Le 1983; Isoh 1986; Skublov and Tyugai 2005; Gornostaeva et al. 2018). In this work, a collection of irghizites and microirghizites selected by the authors during two field seasons of 2018–2019 was studied on the Zhamanshin meteorite crater. The main task set by the authors of the work is the identification and study of mineral inclusions with reference to the morphological features of the samples and the places of their sampling. This study will help to understand the genesis of irisites irghizites and microirghizites and impact glasses of the Zhamanshin astrobleme in general and will provide information for reconstructing the impact event.

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2 Methods and Samples X-ray Tomography. The studies were carried out on a SkyScan 1172 high-resolution computer microtomograph (Bruker, Germany). X-ray source: 20–100 kV, 0–250 µA, resolution: 0.1– 0.2) leads to an increase in the Ca minal in Cpx due to Mg and Fe minals. In studies (Safonov et al. 2014) conducted under gradient-free conditions at 550 MPa, 750–800 °C, it was shown that the addition of CO2 to the composition of H2O-NaCl fluid also does not lead to a shift in the composition of Cpx from the field of Ca-Mg-Fe pyroxenes.

Fig. 2. Quaq-Aeg-Jd ratio (Morimoto et al. 1988) in experiments: 1-A3, H2 O; 2-A4, XNaCl = 0.1; 3-N4, XNaCl = 0.32; 4-C1, XNa2 CO3 = 0.28.

Iron Cpx f = 0.2–0.3 in experiments with H2O (experiments A3, N3, B1 in Table 1). Cpx close ferruginous were obtained in the experiments (Safonov et al. 2014), conducted in the presence of fluid H2O - CO2-NaCl at low salt contents (XNaCl ≈ 0.01–0.05). The increase of the salt content in our experiments (experiments A4, C3, N4 in Table 1) leads to the formation of Cpx with a slightly lower ferruginosity f = 0.1–0.2. In experiments with Na2CO3, the resulting clinopyroxene corresponds to aegirineaugite (Fig. 2). The mineral has a high content of FeO ≈ 22–25 wt.% and TiO2, reaching the first percent. The ferruginous content of the mineral varies in the range f = 0.70–0.80. Thus, it can be argued that clinopyroxenes of the Quad composition indicate that their formation took place in the presence of a metasomatizing fluid, which was dominated by alkali chlorides. The predominant carbonate-alkaline component in the fluid leads to more intensive removal and transfer of Fe with the formation of more ferruginous Cpx than in the cases with H2O ± NaCl fluid. The ratio (Al/(Al + Si + Fe + Mg + Mn + Ti) – (Ca/(Ca + Na + K) in amphiboles formed during the transfer of fluid elements of different compositions is shown in Fig. 3. Prg-Ed amphiboles are formed in the presence of substantially aqueous (1–2 in Fig. 3, experiments A3, N3), as well as NaCl-containing fluids at low salt contents (XNaCl ≈ ≤ 0.1), (3 in Fig. 3). With an increase in XNaCl, the formation of sodiumcalcium amphiboles – vincite - barroisite occurs in the fluid (4 in Fig. 1, experiments C3, N4, Table 1). The carbonate-alkaline fluid (XNa2 CO3 = 0.07) leads to the formation of richterite (5 in Fig. 3, experiment C4, Table 1). In the C1 experiment, at high XNa2 CO3 , amphibole is also formed, approximating the composition of taramite (Fig. 3). Probably, the excess of the fluid relative to the

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183

Fig. 3. The ratio (Al/(Al + Si + Fe + Mg + Mn + Ti) - (Ca/(Ca + Na + K) in amphiboles formed with the participation of a fluid of different composition: 1–2 - H2 O; 3–4 - NaCl; 5 - XNa2 CO3 = 0.07; 6 - XNa2 CO3 = 0.28. The inscriptions in Fig. 3 are the final members of amphiboles according to (Leake et al. 1997): Act - actinolite, Arf – arfvedsonite, Ed – edenite, Eck – eckermanite, Ktp – catophorite, Gln – glaucophane, Prg – pargasite, Rbk – ribekite, Rit – richterite, Tr – tremolite, Ts – cermakite.

suspension and the high concentrations of Na in the fluid can explain the overestimated Na values in this mineral. At the same time, sodium in the composition of film solutions can be adsorbed on the surface of the amphibole, which leads to overestimated readings of its content in the microprobe analysis. However, it is possible that natural alkalinecarbonate metasomatizing fluids do not contain as high XNa2 CO3 as those specified in the C1 experiment.

5 Conclusion As can be seen from the experiments, the composition of the fluid phase filtered through the rocks (along with the P-T parameters and the composition of the host rocks) determines the types of metasomatites. Natural observations and experimental studies show that the introduction of alkalis and silica by filtering solutions in which XNaCl > 0.1 is deposited in the rear zones of the infiltration columns with the formation of acid plagioclases, feldspars and melanocratic ferruginous biotite ± amphibole. In this case, there is a change in the composition of the fluid phase, in particular, a decrease in the content of alkalis in it. Such a substantially aqueous fluid, with low concentrations of chlorides (H+ , Na+ , K+ ), contributes to the removal of Ca, Fe, and Mg from the host rocks. In natural conditions, essentially aqueous fluids with small salt additions are responsible for the formation of basifiers during granitization processes. Both during granitization and basification, the high ferruginous content of the newly formed dark-colored minerals and the abundance of magnetite and hematite are explained by the predominant removal

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of iron from the host rocks in comparison with Mg. Therefore, during the development of ferruginous minerals in metasomatites, chloritization of the host rocks is observed. The presence of carbonate ions in the solution compositions leads to the removal of Si, Ca, and Fe from the rocks and the inertia of Mg (Khodorevskaya 2019). Thus, the appearance of carbonatites without a visible connection with the series of alkaline-base magmatites can be explained by the presence of carbon dioxide-sodium fluids, which ensure the removal of Ca from the host rocks and its redeposition into carbonates. Acknowledgments. The work was performed at the IEM RAS on the topic of research AAAAAAA18-118020590148-3.

References Korzhinsky, D.S.: Granitization as magmatic substitution. Izv AN SSSR. Ser. Geol. 2, 56–69 (1952) Kushev, V.G.: Alkaline metasomatites of the Precambrian, 190 p. L.: Nedra (1972) Savel’eva, V.B., Bazarova, E.P., Sharygin, V.V., Karmanov, N.S., Kanakin, S.V.: Metasomatites of the Onguren carbonatite complex (Western Baikal region): geochemistry and composition of accessory minerals. Geol. Ore Deposits. 59(4), 319–346 (2017) Safonov, O.G., Butvina, V.G.: Reactions-indicators of K and Na activity in the upper mantle: natural and experimental data, thermodynamic modeling. (10), 1–15 (2016) Khodorevskaya, L.I.: Experimental study of the interaction of diopside with H2O-Na2CO3 fluid under pressure gradient conditions at 750 °C. In: Proceedings of the All-Russian Annual Seminar on Experimental Mineralogy, Petrology and Geochemistry (VESEMPG-2019), pp. 122–125 (2019b) Aranovich, L.Y., Newton, R.C., Manning, C.E.: Brine assisted anatexis: experimental melting in the system haplogranite-H2O-NaCl-KCl at deep-crustal conditions. Earth Planet. Sci. Lett. V. 374, 111–120 (2013) Aranovich, L., Safonov, O.: Halogens in high-grade metamorphism. In: Harlov, D.E., Aranovich, L. (eds.) The Role of Halogens in Terrestrial and Extraterrestrial Geochemical Processes. SG, pp. 713–757. Springer, Cham (2018). https://doi.org/10.1007/978-3-319-61667-4_11 Chakhmouradian, A.R., Reguir, E.P., Kressal, R.D., et al.: Carbonatite-hosted niobium deposit at Aley, Northern British Columbia (Canada): mineralogy, geochemistry and petrogenesis. Ore. Geol. Rev. 64, 642–666 (2015) Holness, M.: Equilibrium dihedral angles in the system quartz-CO2-H2O-NaCl at 800°C and 1– 15 kbar: the effects of pressure and fluid composition on the permeability of quartzites. Earth Planet. Sci. Lett. 114, 171–184 (1992) Leake, B.E., Woolley, A.R., Birch, W.D., et al.: Nomenclature of amphiboles. Report of the subcommittee on amphiboles of the international mineralogical association commission on new minerals and mineral names. Eur. J. Mineral. 9, 623–651 (1997) Markl, G., Bucher, K.: Composition of fluids in the lower crust inferred from metamorphic salt in lower crustal rocks. Nature 391, 781–783 (1998) Morimoto, N., Fabries, J., Ferguson, A.K., et al.: Nomenclature of pyroxenes. Amer. Mineral. 73, 1123–1133 (1988) Newton, R.C., Manning, C.E.: Role of saline fluids in deep crustal and upper mantle metasomatism: insights from experimental studies. Geofluids 10, 58–72 (2010) Rankin, A.H.: Fluid inclusion studies in apatite from carbonatites of the Wasaki area of western Kenya. Lithos. 8(2), 123–136 (1975)

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Safonov, O.G., Kosova, S.A., van Reenen, D.D.: Interaction of biotite_amphibole gneiss with the H2O–CO2–(K,Na)Cl fluids at 5.5 kbar and 750 and 800°C: experimental study and applications to dehydration and partial melting in the middle crust. J. Petrol. 55, 2419–2456 (2014) Shmulovich, K.I., Graham, C.M.: Melting of albite and dehydration of brucite in H2 O-NaCl fluids to 9 kbars and 700–900°C: implications for partial melting and water activities during high pressure metamorphism. Contrib. Mineral. Petrol. 124(3–4), 370–382 (1996) Touret, J.L.R.: Fluid regime in Southern Norway: the record of inclusions. In: Tobi, A.C., Touret, J.L.R. (eds.) The Deep Proterozoic Crust in the North Atlantic Provinces. Proceedings of NATO Advanced Study Institute Series, vol. C158, pp. 517–549 (1985) Touret, J.L.R., Huizenga, J.M.: Fluids in granulites. In: van Reenen, D.D., Kramers, J.D., McCourt, S., Perchuk, L.L. (eds.) Origin and Evolution of Precambrian High-Grade Gneiss Terrains, with Special Emphasis on the Limpopo Complex of Southern Africa. Geological Society of America Memoirs, pp. 25–37 (2011)

Trace Elements in Amphiboles from Marbles of Luk Yen Ruby and Gem Spinel Deposit, North Vietnam K. A. Kuksa1,2(B) , P. B. Sokolov2 , M. E. Klimacheva1 , S. G. Skublov3,4 , and I. S. Sergeev1 1 Saint-Petersburg Branch of the Russian Mineralogical Society, Saint Petersburg State

University, Saint-Petersburg, Russia [email protected] 2 SOKOLOV Co. Ltd, Moscow, Russia 3 Saint-Petersburg Branch of the Russian Mineralogical Society, Institute of Precambrian Geology and Geochronology RAS, Saint-Petersburg, Russia 4 Saint-Petersburg Branch of the Russian Mineralogical Society, Saint-Petersburg Mining University, Saint-Petersburg, Russia

Abstract. The composition and mineral associations of amphiboles from marbles of the Luk Yen deposit of colored stones, northern Vietnam have been investigated. It was found that in ruby-bearing marbles, amphiboles are found in association with tourmaline, anorthite, phlogopite and are represented by pargasites and sadanagaites. Moreover, they are enriched in light lithophilic elements (Li, Be, B, K), fluorine, transition metals (Ti, Fe, Cr) and Ga and have more fractionated REE spectra relative to amphiboles from spinel-bearing marbles. At the same time, the latter are associated only with forsterite, clinohumite, and graphite and, in terms of chemical composition, belong to the tremolite-pargasite group. They are characterized by increased contents of V, Rb, Sr, Y, and REE and less fractionated distribution spectra of rare earths. The totality of the obtained data suggests that the formation of ruby-mineralized marbles took place not at the regressive, but at the progressive stage of metamorphism. Keywords: Amphiboles · Geochemistry of rare elements · Ruby · Noble spinel · Marble · North Vietnam

1 Introduction The Luk Yen deposit in northern Vietnam is famous for its gem-quality rubies and noble spinels, which have been mined from marbles and placer deposits developed in the vicinity since the late 70s of the last century. The works of previous researchers were devoted to mineralogy, geochemistry, and genesis of gemstone mineralization and its host marbles (Giuliani et al. 2003; Garnier et al. 2005; Garnier et al. 2008; Huong et al. 2012; Long and Giuliani 2013). In this case, the greatest attention was paid to the conditions of crystallization of rubies and spinel directly, while questions of the chemistry © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 186–193, 2023. https://doi.org/10.1007/978-3-031-23390-6_24

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and conditions of formation of other minerals remained practically unexplored. At the same time, the trace element composition of through minerals associated with rubies and spinel, such as amphiboles, micas, and minerals of the gummite group, can serve as a source of important petrological information. In this work, using the example of amphiboles from ruby- and spinel-bearing marbles from the Luk Yen deposit, North Vietnam, the possibilities of geochemistry of rare elements and petrology in solving the problems of the genesis of the marbles themselves and the gemstone mineralization in them are demonstrated.

2 Materials and Methods Samples of amphibole for the study were taken from three areas within the Luk Yen deposit from the previously identified five gemological groups of marbles (Kuksa et al. 2019). The division into groups was carried out depending on the presence of gemstone mineralization (spinel- and corundum-containing), as well as on the peculiarities of the composition of the marbles: marble with lilac, with red and blue spinel, marble with red rubies and pink sapphires. In the latter case, ruby often replaces spinel along cracks and / or overgrows its grains along the periphery. The analysis of the chemical composition of amphiboles (Na, Mg, Al, Si, Ca, F, Cl) was carried out on a Hitachi S-3400N X-ray microanalyzer with an Oxford XMax 20 attachment. The survey was carried out at the Geomodel RC, St. Petersburg State University under the following conditions: 20 kV accelerating voltage, 1 nA probe current, 20 s. exposure. A total of 109 analyzes of amphiboles were performed with a detection limit of 0.01–0.02 wt% for each element %. The trace element composition of spinels was studied by the LA-ICP-MS method at the certification and testing center of the Institute for Problems of Microelectronics Technology and Highly Pure Materials of the Russian Academy of Sciences (Chernogolovka, Moscow Region) with the following imaging parameters: beam size 45 µm, frequency 10 Hz, flux density 3.50 J/cm2 . A total of 75 samples were studied, at each point the concentrations of Li, Be, B, K, Ti, V, Cr, Mn, Fe, Ni, Co, Ga, Ge, Rb, Sr, Y, REE, Ba, Tl were estimated, Pb. The analysis error was less than 10 rel. % for most items.

3 Object of Study The Luk Yen deposit is located in the slightly altered marbles of the Lo Gam tectonic zone (Garnier et al. 2005). It is composed mainly of calcite and dolomite marbles, which are interbedded with the bodies of amphibolites and gneisses. Gemstone mineralization with differently colored noble spinels and has a bedding in the form of nests, lenses and threadlike veins. The main minerals of the deposit’s marbles are calcite and dolomite. The minor ones include forsterite, clinohumite, phlogopite, amphiboles, anorthite, scapolite, and diopside. Sulfides, graphite, rutile, uraninite, zircon, zirconolite, titanite, epidote, tourmaline, fluorite, and apatite are found in accessory amounts (Kuksa et al. 2019). Amphibole is associated with both rubies and variously colored spinel varieties. At the same time,

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amphibole in marbles with lilac and red spinel is usually represented by hypidiomorphic crystals of green green to emerald green colors, which reach sizes of 0.3–3 cm and sometimes surround spinel grains in the form of a shirt. At the same time, amphibole, which occurs with blue spinel, is usually represented by gray-green idiomorphic crystals with a maximum size of 1 cm. Amphibole, used in ruby-bearing marbles, has a yellow-green color and, as a rule, an idiomorphic habit. Crystals range in size from millimeters to 1–1.5 cm in elongation. Moreover, in one type of marble, amphibole is associated with bright red ruby, phlogopite, anorthite, and tourmaline (sometimes they are found in the form of intergrowths or inclusions). At the same time, such mineral associations are not typical for spinel-bearing marbles.

4 Amphibole Chemical Composition The results of the study showed that all studied amphiboles are of the calcium group. In this case, the compositions of amphiboles from ruby-bearing and spinel-bearing marbles form two non-intersecting fields: the first groups belong to the pargasite-sadanagaite series, while the latter form a continuous trend of tremolite to pargasite. The same pattern can be traced at the level of trace elements - amphiboles associated with rubies statistically significantly differ in the levels of Li, Be, B, K, Ti, V, Cr, Fe, Ge, Rb, Sr, Tl, Y, REE from amphiboles occurring in association with multi-colored spinel (Table 1). Table 1. Results of t-test for amphiboles from ruby-bearing and spinel-bearing marbles of the Luc Yen deposit, S. Vietnam Elements Spinel Ruby t-value (n = 56), (n = 19), average average

p

Spinel (n = 56), st. Deviation

Ruby F-ratio (n = 19), st. Deviation

p

Wt.% Na

1,5

2,4

−9,851

0,000 0,369

0,156

5,610

0,000

Mg

13,0

10,0

23,405

0,000 0,465

0,550

1,403

0,335

Al

7,2

12,5

−17,072 0,000 1,341

0,363

13,622

0,000

Si

23,3

19,2

15,711

0,000 1,119

0,423

6,999

0,000

Ca

10,6

9,9

11,260

0,000 0,187

0,263

1,978

0,055

F

0,26

0,97

−5,271

0,000 0,386

0,768

3,945

0,000

Cl

0,03

0,01

2,327

0,023 0,038

0,000

0,000

1,000

40,4

172,7

−5,196

0,000 42,507

178,3

17,604

ppm Li

0,000

(continued)

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189

Table 1. (continued) Elements Spinel Ruby t-value (n = 56), (n = 19), average average

p

Spinel (n = 56), st. Deviation

Ruby F-ratio (n = 19), st. Deviation

p

Be

13,4

19,6

−3,020

0,003 7,808

7,415

1,109

0,842

B

4,5

40,2

−7,056

0,000 2,905

38,009

171,24

0,000

K

2200

6036

−8,815

0,000 1154

2612

5,122

0,000

Ti

5530

10058

−8,259

0,000 2254

1334

2,852

0,017

V

985

413

4,578

0,000 526

232

5,161

0,000

Cr

713

1674

−4,296

0,000 624

1299

4,340

0,000

Mn

54

62

−0,987

0,327 29

39

2

0,088

Fe

1289

11184

−8,884

0,000 599

8383

196

0,000

Ni

23

7

1,537

0,129 45

4

129

0,000

Co

1,21

1,19

0,021

0,983 2,826

0,614

21,154

0,000

Ga

9,19

24,04

−12,375 0,000 3,538

6,679

3,564

0,000

Ge

0,94

1,19

−1,277

0,206 0,800

0,531

2,273

0,057

Rb

4,34

2,84

2,367

0,021 2,498

1,984

1,586

0,281

Sr

100

27

7,872

0,000 40,258

6,823

34,818

0,000

Y

27

6

4,686

0,000 19,130

2,269

71,072

0,000

Ba

19

22

−0,671

0,504 7,448

25,290

11,530

0,000

La

0,92

0,18

3,553

0,001 0,900

0,127

50,562

0,000

Ce

1,87

0,66

3,245

0,002 1,588

0,485

10,708

0,000

Pr

0,63

0,17

3,969

0,000 0,508

0,077

43,723

0,000

Nd

4,33

1,22

3,966

0,000 3,388

0,507

44,711

0,000

Sm

1,70

0,57

3,788

0,000 1,279

0,225

32,202

0,000

Eu

0,31

0,10

3,919

0,000 0,222

0,029

57,895

0,000

Gd

2,60

0,82

3,943

0,000 1,948

0,304

40,935

0,000

Tb

0,41

0,15

3,668

0,000 0,310

0,056

30,984

0,000

Dy

3,12

1,17

3,585

0,001 2,342

0,415

31,863

0,000

Ho

0,62

0,23

3,670

0,000 0,462

0,081

32,770

0,000

Er

1,77

0,69

3,539

0,001 1,318

0,234

31,658

0,000

Tm

0,22

0,09

3,275

0,002 0,162

0,031

27,130

0,000

Yb

1,26

0,59

2,838

0,006 1,007

0,206

23,843

0,000

Lu

0,14

0,07

2,745

0,008 0,103

0,024

18,693

0,000

(continued)

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K. A. Kuksa et al. Table 1. (continued)

Elements Spinel Ruby t-value (n = 56), (n = 19), average average

p

Spinel (n = 56), st. Deviation

Ruby F-ratio (n = 19), st. Deviation

p

Tl

0,02

0,16

−5,347

0,000 0,010

0,191

382,807 0,000

Pb

0,50

0,69

−1,045

0,300 0,779

0,347

5,043

0,000

AlVI

0,72

1,42

−21,425 0,000 0,136

0,073

3,531

0,005

AlIV

1,38

2,32

−14,961 0,000 0,270

0,071

14,650

0,000

apfu

Note: elements for which statistically significant differences in concentrations in the two groups of marbles under consideration are identified are highlighted in red. Al oct and Al tet denote the proportion of aluminum in the octahedral and tetrahedral positions in the structure of amphiboles, respectively; apfu - formula units

At the same time, amphiboles occurring with spinels of various color shades each have their own geochemical specifics - for example, pargasites in association with blue “cobalt” spinel are almost an order of magnitude richer in Co and Ni relative to amphiboles of other gemological groups and contain increased Mn concentrations, as well as the spinels of this type (Kuksa et al. 2019). At the same time, amphiboles, the richest in V and Cr, are found exclusively with red and lilac spinels, the color of which is caused by the presence of increased concentrations of these elements (Fig. 1).

Fig. 1. Ratio of trace elements in amphiboles of the Luk Yen deposit, S. Vietnam. Legend: 1 and 2 - from ruby-containing marbles, 3 - associated with red spinel, 4 - with purple spinel, 5 - with blue “cobalt” spinel.

In terms of the content of rare earth elements (REE), amphiboles associated with lilac spinel are sharply distinguished - the total content of REE in them varies from 17.3 to 60.0 ppm, averaging 36.6 ppm. In all other groups of amphiboles, the total REE content does not exceed 13 ppm. A characteristic feature of amphiboles associated with red and purple spinel is the presence of a negative Ce-anomaly (Ce/Ce * averages 0.48–0.58).

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In amphiboles from ruby-bearing marbles, the negative Ce anomaly is also manifested, but to a lesser extent (Ce/Ce * is 0.68 on average). In amphiboles from other groups, the Ce anomaly is not expressed. In terms of the degree of manifestation of the negative Eu anomaly, the considered amphiboles practically do not differ. In this case, according to the ratio of the absolute contents of Ce and Eu, amphibole with red and purple spinel and amphibole with blue spinel and rubies form two separate trends (Fig. 2).

Fig. 2. REE ratio in amphibole marbles of the Luc Yen deposit, S. Vietnam. See Fig. 1 for legend.

5 The Discussion of the Results The amphiboles of the Luk Yen deposit are found in various types of marbles in association with rubies, pink corundums, and variegated noble spinels. At the same time, amphiboles associated with red and lilac spinels are usually bright green, while amphiboles associated with blue “cobalt” spinels and corundums are always yellow-green. Despite the limited set of silicate and aluminosilicate phases occurring in these marbles, amphiboles are associated, in addition to rubies, with phlogopite, anorthite, and tourmaline, which is typical of skarn deposits in Burma and China (Alexandrov and Senin 2002; Themelis 2008). At the same time, in addition to amphiboles, spinel contains only forsterite, clinohumite, and graphite. Such mineral parageneses are widespread in other marble deposits of the South Asian fold belt containing gemstone mineralization, and their formation is associated with regional metamorphism of platform carbonate strata containing evaporite interlayers (Garnier et al. 2008). The study of the chemical composition of amphiboles from various types of marbles from the Luk Yen deposit confirmed that they are represented by the Ca-type, however, they form two non-overlapping fields. So, if in ruby-bearing marbles they are represented by the pargasite-sadanagaite group, in the spinel-bearing marbles they are tremolites and pargasites. Moreover, the trace element composition of the mineral also indicates a significant difference in amphiboles associated with spinel and rubies - the latter are significantly enriched in F, Li, Be, B, and Cr and have more fractionated REE spectra and less pronounced Eu and Ce anomalies relative to amphiboles from spinel-bearing marbles.

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At the same time, all amphiboles of the deposit demonstrate a strong positive correlation between the total content of REE and Y, forming a linear trend, which may indicate their formation as a result of a single process, but with a different contribution of the fluid component. On the whole, this is in good agreement with the model proposed by V. Garnier and colleagues (Garnier et al. 2008), according to which gemstone mineralization is formed with a significant involvement of Cl-, F-, H2 S- and CO2 -containing fluids. The results of studying the compositions of Ca-amphiboles from various metamorphic complexes (Skublov and Drugova 2003; Baziotis et al. 2014) showed that the content of AlIV , NaA , and Ti increases with increasing temperature, and that of AlVI and NaB - with increasing pressure (Triboulet 1992). This suggests that the significantly higher contents of these elements in different structural positions in the amphibole of ruby-bearing marbles may be a consequence of the higher temperatures and pressures that existed during their formation. Accordingly, the replacement of spinel by corundum, most likely, did not occur at the regressive stage, as suggested in (Garnier et al. 2008), but at the progressive stage of metamorphism.

6 Conclusion The mineral associations and chemical composition of amphiboles from ruby- and spinelbearing marbles of the Luk Yen deposit, North Vietnam have been studied. It has been established that in spinel marbles the mineral is represented by the pargasite-tremolite group, while in corundum marbles the composition of amphiboles corresponds to pargasites and sadanagaites. Moreover, they form two non-overlapping groups in terms of the ratio of the main and minor elements. Amphiboles associated with differently colored spinels each have their own geochemical specificity, similar to that described earlier for the corresponding spinel type. The trace element composition of amphiboles suggests that the formation of rubycontaining marbles took place at a progressive stage of the metamorphic process with a significant participation of fluids. Acknowledgments. The authors are grateful to the staff of the Geomodel RC V. Shilovskikh, N. Vlasenko, V. Bocharov, who carried out microprobe and Raman studies. Special thanks to V.A.Khvostikov, an employee of the Center of the Institute for Problems of Microelectronics Technology and High-Purity Materials of the Russian Academy of Sciences, for performing the LA-ICP-MS analysis. In carrying out the study, the hardware base of the Geomodel RC and the RC Methods for the Analysis of Matter Composition, Science Park of St. Petersburg State University was used. The study was funded by Sokolov LLC.

References Baziotis, I., Proyer, A., Mposkos, E., Marsellos, A., Leontakianakos, G.: Amphibole zonation as a tool for tracing metamorphic histories: examples from Lavrion and Penteli metamorphic core complexes. Geophys. Res. Abstracts 16, EGU2014-835-1 (2014)

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Garnier, V., et al.: Marble-hosted ruby deposits from central and Southeast Asia: towards a new genetic model. Ore Geol. Rev. 34, 169–191 (2008) Garnier, V., et al.: Age and significance of ruby-bearing marble from the Red River Shear Zone, Northern Vietnam. Can. Mineral. 43, 1315–1329 (2005) Giuliani, G., et al.: CO2 – H2S – COS – S8 – AlO (OH) -bearing fluid inclusions in ruby from marble-hosted deposits in Luc Yen area, North Vietnam. Chem. Geol. 194, 167–185 (2003) Huong, L.T.-T., et al.: Gemstones from Vietnam: an update. Gems Gemol. 48, 158–176 (2012) Long, P.V., Giuliani, G.: Update on gemstone mining in Luc Yen, Vietnam. Gems Gemol. 49(4), 31–46 (2013) Themelis, T.: Gems and Mines of Mogok, p. 352. Themelis Publisher, Thailand (2008) Triboulet, C.: The (Na – Ca) amphibole – albite – chlorite – epidote – quartz geothermobarometer in the system S – A – F – M – C – N – H2O. 1. An empirical calibration. J. Metamorphic Geol. 10, 545–556 (1992) Alexandrov, S.M., Senin, V.G.: Genesis and composition of spinels and their associations in greisenized magnesian skarns and dolomites of the Xianhualing deposit, China. Geokhimiya. [Geochemistry] (9), 952–966 (2002). (in Russian) Skublov, S., Drugova, G.: Patterns of trace-element distribution in calcic amphiboles as a function of metamorphic grade. Can. Mineral. 41(2), 383–392 (2003) Kuksa, K.A., Sokolov, P.B., Marakhovskaya, O., Gussias, G.A., Brownkomb, U.: Mineralogy, geochemistry and questions of the genesis of noble spinel of the Luk Yen deposit, Vietnam. Mineralogiya [Mineralogy] 5(3), 56–69 (2019). (In Russian) Skublov, S.G.: Geochemistry of Rare Earth Elements in Rock-Forming Metamorphic Minerals, 147 p. Nauka Publishing, Saint Petersburg (2005). (in Russian)

Periclase from Kuhilal Deposit, Southwestern Pamirs as a Result of Magnesian Solfats and Chlorites Metamorphism A. K. Litvinenko(B) , D. A. Litvinenko, and A. F. Fedorov Moscow Branch of the Russian Mineralogical Society, Sergo Ordzhonikidze Russian State University for Geological Prospecting (MGRI), Moscow, Russia [email protected]

Abstract. For the first time, periclase was discovered at the Kukhilal deposit located in the Southwestern Pamirs in the Goranian series, which underwent polycyclic metamorphism from granulite to high-temperature amphibolite facies. The deposit is localized in magnesian skarns of the abyssal facies. This mineral characterizes the low-pressure, high-temperature - periclase facies of metamorphism. Its presence in the Southwestern Pamirs (apart from Kukhilala, periclase was found in two more points) is an unusual fact. We explain the formation of periclase outside its facies setting not by the metamorphism of magnesian carbonate rocks, but by the result of changes in sulfate and chloride mineral associations that arose in evaporite salt-bearing sediments in the Early Archean. The presented study provides data on the geological position of periclase-bearing rocks, paragenesis of periclase, diagnostics of the mineral, chemical composition and trace elements, as well as possible conditions for its formation. Keywords: Southwestern Pamir · Kuhilal · Goranian series · Magnesian skarns of the abyssal facies · Granulite facies · Periclase facies · Periclase · Forsterite · Spinel · Phlogopite · Evaporite sedimentation · Sulfates and chlorides

1 Factual Materials and Research Methods We found periclase in stone material sampled at site No. 5 in the Main skarn zone, in dolomite marbles on the left side of the river. Bijunt and in sai Changin magnesite marbles. It was observed only in thin sections and was diagnosed by the octahedral shape of grains, perfect cleavage in two directions, intersecting at an angle of 90° and high relief. Optical diagnostics was confirmed by microprobe (N.N. Kononkova, GEOKHI RAS), energy dispersive analysis (V.D. Shcherbakov, Moscow State University) and La-ISP-MS method (E. Minervina, IGEM, RAS).

2 Geological Position of the Research Object The Kukhilal jewelry spinel and clinohumite deposit is located in the tectonic zone of the Southwestern Pamir, which is a fragment of the Nuristan-Pamir median massif © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 194–201, 2023. https://doi.org/10.1007/978-3-031-23390-6_25

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in the Cimmerian Afghan-South Pamir fold region (Litvinenko 2004). In the structure of the Southwestern Pamirs, three Late Archean (Goran, Khorog, Shakhdara) and one Early Proterozoic (Alichur) series, as well as the separating pluton of the Pamir-Shugnan granitoids of the Cretaceous-Paleogene age, have been distinguished (Dismemberment of stratified and intrusive formations of Tajikistan 1976). The study considers only mineral complexes of the Goran Group with a thickness of more than 4000 m. The series is represented by the paragenesis of rhythmically alternating marbles (meta-limestones, metadolomites, metamagnesites) with quartzites (metapsamites) and biotite gneisses (metapelites) with interlayers of basic and intermediate metavolcanites (amphibolites). In the summary section of the series, more than two dozen rhythms are distinguished (Kiselev and Smolin 1979), each of which is expressed by alternating metapsamites, metapelites, metapelites with interlayers of carbonate rocks and metavolcanics. The base of each rhythm contains one of the first three components, and the top contains meta-limestone, metadolomite, or metamagnesite. Elementary rhythms are combined into overrhythms with a thickness of 350 to 1000 m. A feature of the rhythm is the increase in the carbonate content of the rocks both from the base of the rhythm to its top and up the section of the series as a whole, as well as in the increase in the magnesium content of the marbles to the tops of the overrhythms. Almost all overrhythms are completed with dolomite, and in the upper part of the section - with magnesite marbles. The latter form beds and lenses in dolomite packs, the total number of which, in the section of the series, reaches five. In the upper half of the section, the marking horizons that fix the extreme members of the rhythms are magnesite marbles (“white” rocks) and graphitized kyanite-bearing metamorphites (“black” rocks), occurring at the top and bottom of the rhythms, respectively. The graphite of Kukhilala, and in other areas of the Goranian series, is organogenic in nature, being a product of the metamorphism of a living protein (algae) substance (Smolin 1991). The upper half of the section of the series differs from its lower part in the significant specific gravity of carbonate rocks, among which dolomite and magnesite marbles predominate. They are associated with “white shales” - high-magnesian and aluminous rocks composed of kyanite, talc, gedrite, cordierite, cornerupine, sapphirine, and phlogopite. These minerals are characterized by a very low iron content (Litvinenko 2003). The rocks of the series are enriched in B, P, F, Sr, Li, Rb, etc. (Budanova 1991). The dolomite-magnesite part of the Goranian series has a pronounced mineragenic individuality. It is determined by deposits of noble spinel, clinohumite and lapis lazuli. In paragenesis with the latter, scapolite, hayuin, sodalite are often found - minerals, which include Na, Cl, S in significant amounts. The listed features, according to the conclusion of many researchers, indicate that the upper part of the Goran Group belongs to the group of evaporite formations (Budanova 1991; Litvinenko 1998). The Goranskaya series and, accordingly, the Kuhilal deposit, underwent regional polycyclic metamorphism in the thermodynamic parameters of granulite (T from 750 to 900 °C, P from 8 to 11 kbar), high-temperature amphibolite, epidote-amphibolite and greenschist facies (Dismemberment of stratified and intrusive formations of Tajikistan 1976; Budanova and Budanov 1983; Litvinenko 2004). The deposit is localized in the lens of magnesite marbles, which make up the upper part of the Goran series section. The lens is 1.2 km long and more than 0.5 km thick

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(Gurevich 1987), occurring among migmatites and black biotite gneisses, containing sillimanite in noticeable amounts. The magnesite lens contains layer-by-layer bodies of granitoids and slightly altered gneisses (Fig. 1). The Kukhilal deposit belongs to the magnesian-skarn formation (Kiselev and Budanov 1985) of the abyssal facies (Litvinenko 2003). The main minerals of the formation are enstatite, forsterite, talc, phlogopite, clinohumite and spinel with large accumulations of pyrrhotite and pyrite. Their feature is a very low iron index, not higher than 1.6% (Litvinenko 2003). These minerals are partially (sometimes completely) replaced by hydrotalcite, clinochlore, serpentine, brucite, etc. Magnesite marbles contain numerous deposits of magnesian skarn. The largest Main skarn zone is confined to the hanging flank of magnesites (Fig. 1). It is traced along the strike for 1000, and the thickness reaches 85 m (Gurevich 1987). 2 sites have been explored in its contours. Extraction work is underway on-site No. 5.

3 Results Periclase is localized in white medium-coarse-grained forsterite skarns (fifth site) with large disseminations of pink spinel from 0.5 to 20 cm and bright yellow clinohumite from 0.5 to 8 cm in diameter. Forsterite in separate grains is colorless and transparent. Their clusters give its aggregate a white color. It is partially serpentinized and chloritized. Periclase is observed in three mineral associations, where it has formed two-mineral parageneses (Litvinenko and Romanova 2020). 1. Inside forsterite skarns, it occurs in the form of colorless, often isometric, large crystals and intergrowths, more than 3 mm in diameter. They have straight, sharp contacts with smaller forsterite grains. Periclase is characterized by a well-pronounced cleavage in two directions, intersecting at an angle of 90° and a high relief (Fig. 2). No solid inclusions were observed in it. Optical diagnostics of periclase, verified by microprobe analysis (average of 3 analyzes, in wt%): SiO2 – 0.24, TiO2 – 0.01, Al2 O3 – 0.02, FeO – 0.07, MnO – 0.04, MgO – 89.91, CaO – 0.13, Na2 O – 0.06, K2 O – 0.01, Cr2 O3 – 0.01, V2 O3 – 0.03, NiO – 0.01, CoO – 0.01: the sum is 90.55 wt%. The analyzes were performed according to the usual program, therefore the MgO value does not reach 100%. 2. In the phlogopite-spinel-forsterite aggregate, periclase is observed in contact with the noble spinel, which is framed by coarse-flaked crystals of hydrotalcite. The size of the periclase is more than 2 mm, the contacts are sharp. It is different from spinel the presence of clear lines of cleavage in two directions, intersecting at right angles and a lighter, better polished without shagreen surface. This may be due to its lower refractive index as well as its lower hardness, making it easier and better polished. Periclase framed by phlogopite is shown in Fig. 3. 3. Periclase is noted in large and yellow crystals of clinohumite, where it is observed in the form of abundant dissemination of microinclusions. They are colorless, transparent, have an octahedral habit with rounded edges and tops, reaching 1 mm in cross section. Its optical diagnostics in this association was confirmed using a scanning electron microscope. In the presented study, periclase is proved by the data of optical microscopy. It is easily diagnosed by a distinct cleavage in two directions, intersecting at an angle of 90° and slightly lower reliefs in relation to the spinel (Fig. 4).

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Fig. 1. Schematic geological map and section of the Kuhi-Lal deposit. Compiled by Ya.A. Gurevich (1987) with additions and changes by the authors.1 - deluvial deposits. 2 - sillimanite-bearing gneisses and migmatites. 3, 4 - marbles: 3 - dolomite, 4 - magnesite. 5 - granites, plagiogranites, pegmatites, aplites. 6 - altered gneisses. 7, 8 - magnesian skarns: 7 - enstatite with talc and gedrite-kyanite rocks, 8 - spinel-forsterite. 9 - thrust. 10 - faults.

Numerous impurities were found in the composition of periclase, a simple oxide, in wt%: Fe 0.7–0.8, Ti 0.4, Ba 0.3, Mn 0.06, Cr, V and La each 0.01, Ce 0.02, Nd ~ 0.01, Co 0.01–0.04, Ni 0.001–0.008, B 0.01–0.03, U ~ 0.03.

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Fig. 2. Periclase at the edge of the thin section. Lens 2.5x. Grain over 3 mm.

4 The Discussion of the Results The periclase identified by us is of great petrological and genetic significance. Its presence in the Goranian Group, which underwent high-pressure granulite metamorphism (Budanova 1991), is not an ordinary, not regular phenomenon, since this mineral is characteristic of magnesian rocks formed under low-pressure conditions of metamorphism (Deer et al. 1966). In the facies of depth (Korzhinsky 1957), periclase characterizes high-temperature, but shallow conditions of mineral formation at pressures less than 2 kbar. Thus, the distribution of periclase is limited by depth conditions and it is found in magnesian skarns only of the hypabyssal facies (Shabynin 1973). Periclase is classified (Marakushev and Bobrov 2005) as a mineral of the pyroxene-hornfels facies, which is characterized by high temperatures and low pressures. It belongs to the typomorphic minerals of shallow magnesian skarns (Pertsev 1977). In this system of rocks, it indicates the periclase facies of depth and is formed during the decarbonatization of dolomites (Marakushev et al. 2000) according to the reaction: CaMgCO3 = CaCO3 + MgO(periclase) + CO2 .

(1)

Our discovery of periclase at the Kukhilal deposit, which, like the entire Goran Group, formed at great depths, at least 30 km at a lithostatic pressure of 9–11 kbar (Budanova 1991; Litvinenko 2004), changes the prevailing idea of its genesis, since the great depth and the corresponding large partial pressure of CO2 in the fluid should

Periclase from Kuhilal Deposit, Southwestern Pamirs

Fig. 3. Periclase in paragenesis with phlogopite. Lens 2.5x. Grain size 3.3 × 2.5 mm.

Fig. 4. Periclase in contact with spinel. Lens 2.5x. The top grain is 3 mm long.

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prevent its crystallization (Pertsev 1977). This pattern cannot be used to explain the formation of the Cuhilal periclase. Therefore, we assume that this periclase arose not from magnesium carbonates - magnesite and dolomite (according to the above data, this reaction is “forbidden” for the Southwestern Pamirs), but either from sulfates or magnesium chlorides. To establish the prototype of the deposit, we assumed an evaporite carbonate-sulfate-chloride magnesian composition (Litvinenko 2012). In this regard, the most realistic reaction of the formation of periclase according to epsomite: MgSO4 · 7H2 O → MgO(periclase) + SO3 + 7H2 O.

(2)

The second possible reaction of the formation of periclase, probably, could pass through bischofite: MgCl2 · 7H2 O → MgO(periclase) + 2HCl + 5H2 O.

(3)

The periclase discovered by us can be considered as an indicator of magnesian sulfates and/or chlorides in the composition of the evaporite prototype of the Kuhilal deposit. The age of this substance appears to be before Late Archean, probably Early Archean. This makes it possible to pose several important lithological problems about the processes of sedimentation in the Early Archean and its transformation during the metamorphism of the earth’s crust rocks under conditions of high temperatures and pressures. The extremely variegated chemical composition of ancient sediments can be judged by the complex spectrum of numerous isomorphic inclusions in a simple oxide - periclase. It contains titanium, iron, barium, REE, cobalt, boron and uranium in appreciable quantities. In addition to Kuhilala, periclase was found in dolomite marbles of the river valley. Bijunt 15 km to the north and on the starboard side of the Stazh River 18 km to the south. This proves the widespread occurrence of periclase in magnesian marbles of the Southwestern Pamirs.

5 Conclusion The periclase we have established allows us to associate the Kuhilala magnesites with sedimentary rocks of evaporite origin. This shows that in the Early Archean, sedimentation processes were very similar to those of the Phanerozoic. Magnesite and dolomite marbles of the Goran Group also contain periclase; therefore, the evaporite sedimentation cycle, which probably took place in the Early Archean, can be extended to the entire development area of this series. The finding of periclase in the Goran Group is another argument in favor of the evaporite origin of the upper part of the Goran Group section.

References Budanova, K.T.: Metamorphic formations of Tajikistan, 336 p. Donish, Dushanbe (1991). (in Russian)

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Budanova, K.T., Budanov, V.I.: Metamagmatic formations of the Southwestern Pamirs, 275 p. Donish, Dushanbe (1983). (in Russian) Gurevich, Y.A.: Features of the geological structure and exploration of deposits of noble spinel Kukhi-Lal (South-West Pamir). Geologiya, poiski i razvedka mestorozhdenij cvetnyh kamnej Tadzhikistana [Geology, prospecting and exploration of deposits of colored stones in Tajikistan]. Dushanbe 17–20 (1987). (in Russian) Deer, W.A., Howie, R.A., Zusman, J.: Rock-Forming Minerals, vol. 5, pp. 9–11. Mir Publishing, Moscow (1966). (in Russian) Kiselev, V.I., Smolin, P.P.: Rhythmology and magnesite content of the Goran Group of the Southwestern Pamirs. Metamorfogennoerudoobrazovanie rannego dokembriya [Metamorphogenic ore formation of the Early Precambrian]. Apatity, 126–134 (1979). (in Russian) Korzhinsky, D.S.: Physicochemical Foundations of the Analysis of Mineral Paragenesis, p. 136. Academy of Sciences of the USSR, Moscow (1957). (in Russian) Litvinenko, A.K.: About the source of things two lapis lazuli deposits. Dokl. AN Respubliki Tadzhikistan [Report of the Academy of Sciences of the Republic of Tajikistan] 61(7), 46–54 (1998). (in Russian) Litvinenko, A.K.: Genetic position of noble spinel in magnesian skarns of the Southwestern Pamirs. Zapiskivserossijskogo mineralogicheskogo obshchestva. [Notes of the All-Russian Mineralogical Society] (1), 76–81 (2003). (in Russian) Litvinenko, A.K.: Nuristan-South Pamir province of Precambrian gems. Geologiyarudnyh mestorozhdenij. [Geology of ore deposits] 46(4), 305–312 (2004). (in Russian) Litvinenko, A.K.: Minerageny of precious stones in Nuristan-South Pamir Province, 315 p. Palmarium Academic Publishing (2012). (in Russian) Litvinenko, A.K., Romanova, E.I.: Periclase in Magnesian skarns of the abyssal facies of the Kukhilal deposit, South-Western Pamir. Razvedka i ohrananedr [Exploration and conservation of mineral resources], 6, 30–34 (2020). (in Russian) Marakushev, A.A., Bobrov, A.V., Pertsev, N.N., Fenogenov, A.N.: Petrology. I. Nauchnyj mir. [Scientific World], 316 p., Moscow (2000). (in Russian) Marakushev, A.A., Bobrov, A.V.: Metamorphic Petrology, 254 p. Moscow State University, Moscow (2005). (in Russian) Pertsev, N.N.: High-Temperature Metamorphism and Metasomatism of Carbonate Rocks, 255 p. Nauka Publishing, Moscow (1977). (in Russian) Dismemberment of stratified and intrusive formations of Tajikistan, 207 p. Donish, Dushanbe (1976). (in Russian) Shabynin, L.I.: Formation of Magnesian Skarn, 211 p. Science Publishing, Moscow (1973). (in Russian)

Monazit of Pizhemskogo, Yarega Deposits and Occurrence of Ichetju, Experience of Chemical Dating A. B. Makeyev1(B) and A. O. Krasotkina2 1 Moscow Branch of the Russian Mineralogical Society, Institute of Geology of Ore Deposits,

Petrography, Mineralogy and Geochemistry of RAS (IGEM RAS), Moscow, Russia [email protected] 2 Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences (IPGG RAS), St.-Petersburg, Russia

Abstract. The study of typomorphic features and age of monazite from two giant titanium deposits of Timan - Pizhemskoye and Yarega, as well as the occurrence of Ichetyu (spatially related to Pizhemskoye) made it possible to establish differences in morphology, in the species composition of inclusions, grain sizes, distribution of chemical varieties of the mineral, associated with the conditions of its crystallization and different sources of the substance. The isochronous Th-Pb age of monazite was calculated using the CHIME method. Crystals of yellow monazite from the Ichetyu occurrence are represented by the La-Ce variety, the time of their crystallization (recrystallization) is estimated at 518 ± 40 Ma. The formation time of the Nd-Ce-variety of monazite-kularite (oolitic appearance, grayish-brown color) is 978 ± 31 Ma. Three isochrones with ages 1301, 1105, and 778 Ma were constructed for the Yarega monazite; for the Pizhemsky monazite-kularite, one isochron with an age of 782 Ma. The source of the high-thorium monazite of the Yarega deposit could be ancient granite batholiths, and the origin of the low-torium Yarega monazite and Nd-Ce-monazite-kularite of the Pizhemskoe deposit with an age of ~ 780 Ma could be associated with the hydrothermal transformation of the weathering crust by lamprophyres similar in age (spessartites and kersantites) of the Chetlas Stone. Keywords: Pizhemskoye and Yarega titanium deposits · Occurrence of Ichetyu · Timan · Monazite · Kularite · Age by CHIME method

1 Factual Materials and Research Methods A study of typomorphic features and age of monazite of two giant titanium deposits of Timan - Pizhemskoye and Yarega was carried out (Makeyev 2016; 2019; Makeev et al. 2020), as well as the polymineral manifestation of Ichetyu, which made it possible to establish differences in morphology: Yarega - fragments of crystals, and the Pizhemskie and Ichetyu - elliptical oolitic grains, hydrothermally altered. Monazite was analyzed at IGEM RAS on a JXA-8200 wave microanalyzer with five X-ray spectrometers, voltage 20 kV, current 150 mA, probe diameter 5 µm. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 202–212, 2023. https://doi.org/10.1007/978-3-031-23390-6_26

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2 The Yarega Oil-Titanium Giant Deposit Deposit located in South Timan, is one of the largest deposits in Russia (over 49% of domestic titanium) and one of the largest deposits in the world (over 10% of world

Fig. 1. Electron microscopic images (BSE mode) of grains of Yarega monazite (1–9) and Pizhemsky (1–19) monazite-kularite with inclusions of quartz (black) and florensite (gray 7.15).

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reserves) in terms of titanium reserves, which are estimated at billions of tons. Its ores oil-bearing quartz sandstones with leucoxene - are among the richest in Russia in terms of titanium dioxide content (10.4 wt%). Despite the high estimate of the ore reserves of the Yarega deposit, it differs from other titanium deposits in its non-standard phasemineral composition: leucoxene-quartz, and belongs to the primary metamorphogenic genetic type (Tigunov et al. 2005). Grains and fragments of crystals of Yarega monazite were recovered from the ultraheavy fraction of a large-volume (several tons) technological sample. They have small sizes 84 × 49–110 × 80, average 93 × 63 µm, isometric or slightly elongated irregular shape with perfect cleavage; inside grains, apart from rare inclusions of quartz, other phases were not found (Fig. 1). Yarega monazite is concentrated in a fine grains ( Os); 4) fluid-metamorphogenic iridist-platinum type in light medium- and coarse-grained dunites, clinopyroxenites and chromitites (Pt > Ir); 5) magmatogenic-fluid-metasomatic palladium-platinum type in metasomatites after dunites (Pt > Pd). A detailed study of

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the ontogeny of PGMs in the Kondyor Massif made it possible to develop a model of the polycyclic formation of placer-forming formations of mineralogical and geochemical types (Mochalov 2013, 2019). With the help of 190 Pt – 4 He dating, the isochronous age of the RMF of mineralogical-geochemical types was established, corresponding: for Pt, Pt > Os and Pt > Ir - 143 ± 7 Ma; for Pt, Pt > Os, Pt > Ir and Pt > Pd - 128 ± 6 Ma; for Pt > Pd - 115 ± 6 Ma, a confirmation of the polycyclic model was obtained and the duration of the PMP formation was determined to be ~ 30 Ma in the development of the Mesozoic tectonic-magmatic activation of the Aldan Shield (Mochalov et al. 2021).

3 Results FCs were found among PMP Pt > Pd type. It is better to examine the FC with an electron microscope (Fig. 1a). Large FCs visually resemble beams of “platinum herb” on the crystal faces (Fig. 1) and on the porous surface of isoferroplatinum pseudomorphs.

Fig. 1. Twins of growth along (111) of cubic PMP crystals “overgrown” with whiskers, which have arisen during the process of multi-headed facet growth. a - hereinafter BEC - backscattered electron image; SEL - secondary electron image. b - photo width 2 mm.

Cubic crystals of the Pt > Pd type, most often twinned (Makhorkina et al. 1994; Cabry and Laflamme 1997; Shcheka et al. 2004, etc.). The chemical composition of cubic single crystals approximately corresponds to the isoferroplatinum formula - Pt3−x Fe1+x (Table 1). The main habit forms of isoferroplatinum crystals are {100}, rarely {111}. Some twins, according to the results of X-ray analysis, are represented by cryptoaggregates of isoferroplatinum (Pm–3m) and tetraferroplatinum (P4/mmm). Crystals grow together parallel to the (111) or (112) planes, rarely along the (100) plane. The growth of faces leads to the formation of twins according to the fluorite law and, less often, according to the spinel law. Porous pseudomorphs of dissolution can be observed in the form of corrosive porous rims (Fig. 2 a), shadow forms of platinum proto-minerals of all mineralogical and geochemical types (Table 1), in the form of inherited skeletons or frameworks. Porous dissolution pseudomorphs are formed, with a decrease in the volume of the proto-mineral. The species composition of the pseudomorphic minerals

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itself remains the same as that of the protomineral (isoferroplatinum, native platinum, tetraferroplatinum, their cryptoaggregates). Table 1. Composition of PMP for mineralogical, geochemical and genetic types of the Kondyor massif Mineral intergrowth; f.c.

n

Pt

Ir

Os

Ru

Rh

Pd

Fe

Cu

Ni

Pt magmatogenic-fluid-metasomatic dunites and pyroxenites Ol, Cpx, Spl

33

f.c. Pt3-x Fe1+x C

1

f.c. Pt3-x Fe1+x

88,9

0,12

0,08

0,09

0,92

0,60

8,31

0,57

0,13

2,883

0,004

0,003

0,006

0,057

0,036

0,941

0,057

0,014

89,2

0,00

0,01

0,08

0,59

0,10

9,27

0,58

0,06

2,854

0,000

0,000

0,005

0,036

0,006

1,036

0,057

0,006

Pt > Os magmatogenic-fluid-metasomatic pyroxenites Cpx

37

f.c. Pt3 Fe

88,8

0,37

0,29

0,09

1,05

0,70

7,56

0,71

0,06

2,918

0,012

0,010

0,006

0,065

0,042

0,868

0,072

0,007

Pt > Ir fluid-metamorphogenic dunite and pyroxenite Ol, Cpx, Spl

86,3

2,20

0,38

0,11

0,72

0,28

8,81

0,64

0,13

f.c. Pt3-x Fe1+x

2,780

0,072

0,013

0,007

0,044

0,017

0,991

0,063

0,014

Ps (Ol, Cpx) 13

86,5

2,24

0,32

0,08

0,58

0,3

9,08

0,59

0,19

f.c. Pt3-x Fe1+x

2,767

0,073

0,010

0,005

0,035

0,018

1,014

0,058

0,020

87,8

1,45

0,01

0,01

0,89

0,11

8,94

0,76

0

2,815

0,047

0,000

0,001

0,054

0,006

1,001

0,075

0,000

C

63

2

f.c. Pt3-x Fe1+x

Pt > Pd magmatogenic-fluid-metasomatic metasomatic rocks Ol, Cpx, Spl

70

f.c. Pt3-x Fe1+x C+T f.c. Pt3-x Fe1+x

99

88

0,12

0,13

0,07

0,68

0,87

8,79

0,79

0,21

2,814

0,004

0,004

0,004

0,041

0,051

0,982

0,078

0,022

88,4

0

0,02

0,07

0,48

0,74

9,39

0,63

0,05

2,813

0,000

0,001

0,004

0,029

0,043

1,044

0,062

0,005

Note. Ol - olivine, Cpx - clinopyroxene, Spl - Cr-spinel, Ps - pseudomorphism, C - crystals, T twins. n is the number of analyzed chips; f.c. - formula coefficients of isoferroplatinu

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The nuclei of PMP crystals Pt > Pd type can be found in polished thin sections and on grains at high magnification in the composition of porous pseudomorphs after early PGMs (Fig. 2). In pseudomorphoses, one can also find “populations” consisting of a multitude of crystals that have emerged and begun to grow. Single such crystals were found among serpentine or in chalcopyrite-malachite nests in apatite-titanomagnetitebiotite-amphibole-clinopyroxene metasomatites. The nucleation of crystals is observed in pseudomorphosis (both inside and on the surface) and outside it. This is due to the transfer of Pt from the porous zone.

Fig. 2. “Populations” consisting of a multitude of crystals that have originated and started their growth in a border pseudomorphosis of dissolution of proto-PMP (a): b - growth steps are visible on the edges of the cube; c - small twins of cubic crystals and their aggregates; d - irregular intergrowth of cubic crystals with growth figures on the {100} faces.

Already at the stage of the onset of growth, larger regular accretions of two or more crystals are distinguished from the total mass of nuclei, among which twins are observed. The pseudomorphization of early (relict) PMP suggests a Pt oversaturation of mineralforming fluids. From such a supersaturated fluid, PMP nuclei are first formed within the framework of a porous pseudomorphosis, on relict seeds of proto- PMP. Later, in the process of crystal growth, the nearest parts of the porous pseudomorphisms of the PMP dissolve, and at the same time Pt and Fe are partly used to build a growing crystal, and partly carried out by solutions from the pseudomorphosis. Thus, in the space of the “mother” pseudomorphosis, a cavity is formed in which individual crystals, twins

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and druses grow. The formation of PMP crystals in such a pseudomorphic cavity occurs as a result of their free growth, which can explain the fact that some PMP crystals are ideally shaped on all sides, and neither the edges nor the edges bear imprints of the silicate substrate. It can be assumed that large ideal PMP crystals could arise in this way only within the limits of pseudomorphs along large nuggets of the Pt > Ir-type PMP. Pt and Fe redeposited by means of fluid are first fixed as small crystals on the surface of pseudomorphs. In such a crystal, one (xenomorphic) part grows together with the relict part of the PMP, while the other grows in contact with the minerals of the silicate matrix. Subsequently, platinum-bearing fluids release Pt and Fe among the minerals of metasomatites, as evidenced by xenomorphic surfaces on individuals of the PMP in intergrowths with clinopyroxenes, magnetite, amphibole, apatite, biotite, titanite, etc. later into malachite. Aggregates of PMP crystals often grow together. Signs of multiple nucleation and growth of late crystals on early PMP crystals are also observed. The growth of crystals was carried out according to the stepwise-layered, mosaic-block and, probably, skeletal mechanisms. FCs and their aggregates look very original (Fig. 3). The dimensions of the FC are from 2–15 microns in thickness and up to 4 mm in length. In external form, it is well-cut and strongly elongated square or rectangular prisms. At the vertices, some FCs split into two strands. A relatively coarse shading parallel to the elongation is sometimes observed on the edge of the prism. At high magnification, very fine shading can be seen on the edges of the prism, creating a picture of X-shaped intersecting convex and concave stripes a few hundredths of a micron wide (Fig. 3d). Such shading may be the result of subtle polysynthetic twinning. The backscattered electron image shows that this pattern is due to the alternation of wider bands of isoferroplatinum (bright phase) and narrow bands of tetraferroplatinum (darker phase). Thus, FCs are cryptoaggregates of an oriented cubic phase - isoferroplatinum and tetragonal - tetraferroplatinum. They can develop as subindividuals on the cube faces of isoferroplatinum crystals. Rarely are “frameworks” of numerous FCs that seem to continue the growth of the {100} face of the crystal (Fig. 3a) and even form separate “framework crystals” with pronounced {100} and {111} faces, which are fused with “ normal “isoferroplatinum crystal, also formed by {100} and {111} faces (Fig. 3b). As a rule, the formation of isoferroplatinum aggregates ends with the appearance of FCs (Fig. 3e).

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Fig. 3. FC PMP. a - “framework” of numerous FCs - the product of multi-headed growth of the {100} face of the isoferroplatinum crystal. b - “frame crystal” with pronounced skeletal forms on the {100} and {111} faces of the isoferroplatinum crystal. c, d - subindividuals bent in the process of growth: d - on the faces of the pseudo-prism, a regular accretion is observed - an epitaxic or syntactic “lattice” composed of parallel (111) lamellae of isoferroplatinum (light stripes) and tetraferroplatinum (dark stripes). e - an aggregate of cubic PMP crystals with FC grown on the {100} face.

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4 The Discussion of the Results FCs and their aggregates should be classified as forms associated with skeletal and multiheaded growth. They often appear on the surface of isoferroplatinum crystals or twins as a result of continued uneven facet growth. The form subindividuals on the surface of crystal faces are cubic or tabular (flattened pseudo-tetragonal prism). Crystals often divide into separate blocks during growth, somewhat rotated relative to each other, and mosaicism appears at the faces. Large blocks of this “mosaic” sometimes exhibit structures of mosaic growth of lower orders, especially in crystals with elements of deformation bending. In isoferroplatinum crystals with a mosaic structure, thin slit-like cavities filled with silicates are observed between the subindividuals. Probably, the process of multi-headed growth of such crystals was accompanied to a small extent by their splitting, as a result of which the subindividuals began to grow separately. At the same time, multi-headed growth can also occur as a result of epitaxial growth of small crystals on the edge of large crystals or during the intergrowth of isoferroplatinum crystals of a single population within a framework pseudomorphosis. In this case, it is likely that intergrown crystals in the process of joint growth are oriented parallel or subparallel to each other, turning into a single crystal. FCs appear when the growth of skeletal crystals continues. In fact, these are wellfaceted cubes, strongly elongated in one direction, or tetragonal prisms. Some of the thicker crystals of this kind stand out as corrugations along the elongation. We were able to find the answer to this corrugation on tetragonal prisms 0.2 mm and 0.7 mm thick (Fig. 4). It can be seen that the tetragonal prism consists of many intergrown FCs, the edges and faces of which give rise to corrugation. Intergrowths of several crystals are observed, including split highly elongated tetragonal prisms, some of which continue as a bundle of whiskers.

Fig. 4. An intergrowth of two cubic PMP crystals strongly elongated along [100] (tetragonal prism) on a block one. b - a fragment, it can be seen that the tetragonal prism consists of many accrete FCs.

It seems that the growth of whiskers, probably, for the most part occurred at the base, above micron-sized pores on the surface of a pseudomorphosis or crystal, through which the mineral-forming fluid entered. In cases when adjacent micron pores merged, the NC became more “powerful” with a “horned head”. Thus, the growth of NC genetically differs from the dendritic multi-headed growth, when the crystals grow at the vertices.

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5 Conclusion The described FCs, as well as large PMP crystals, have no analogues in the world. They are not found in the known alkaline-ultrabasic massifs and their placers. They are also not found in similar unique placer deposits of the Urals and their primary sources - initially cumulative gabbro-pyroxenite-dunite plutons. Of course, only genetic mineralogy can solve this riddle. Acknowledgments. The author is grateful to O.L. Galankina, E.M. Goryacheva, N.N. Kononkova for her practical assistance in conducting research. The work was carried out according to the research plan of SRL IPGG RAS (SEM-EDA) and supported by the Russian Science Foundation - No. 22-27-00342 (mineralogy, interpretation).

References Geology, Petrology and Ore Content of the Kondyor Massif, 180 p. Nauka Publishing, Moscow (1994) (in Russian) Makhorkina, T.I., Mochalov, A.G., Zhirinovsky, I.V.: Crystals of isoferroplatinum, laurite and sperrylite from the placer deposit of palinodes r. Kondyor. In: VII Mezhdunarodnyj platinovyj simpozium [VII International Platinum Symposium], pp. 65–70. Moscow Contact Publishing, Moscow (1994) Mochalov, A.G.: A genetic model of PGM hosted in cumulative gabbro–pyroxenite–dunite complexes of the Koryak Highland, Russia. Geol. Ore Depos. 55(3), 145–161 (2013) Mochalov, A.G.: Remarkable platinum minerals of the Konder Massif (Khabarovsk Krai, Russia). Mineral. Almanac 23(3), 128 p. (2019). Mineral-Almanac Ltd./Ocean Hictures Ltd. USA, Moscow (2019) Mochalov, A.G., Galankina, O.L.: Features of ontogeny of placer-forming platinum minerals under conditions of polycyclic formation of the alkaline-ultramafic massif Konder (Khabarovsk Krai, Russia). In the book: Evolution of the Material and Isotopic Composition of the Precambrian Lithosphere, pp. 459–499, 669–675. IPA VUZov, St. Petersburg (2018). (in Russian) Mochalov, A.G., Zhernovsky, I.V., Dmitrenko, G.G.: Composition and abundance of native platinum and iron minerals in ultramafic rocks. Geologiya rudnyh mestorozhdenij. [Geol. Ore Deposits] (5), 47–58 (1988). (in Russian) Mochalov, A.G., Yakubovich, O.V., Zolotarev A.A.: Structural transformations and retention of radiogenic 4 He in platinum minerals under mechanical deformations. Dokl. Earth Sci. 480(1), 591–594 (2018) Mochalov, A.G., Yakubovich, O.V., Stewart, F.M., Bortnikov, N.S.: New evidence of the polycyclic genesis of platinum placer-forming formations of the Kondyor alkaline-ultramafic massif: results of 190 Pt–4 He dating. Dokl. Earth Sci. 498(1), 372–378 (2021) Nekrasov, I.Ya., Lennikov, A.M., Oktyabrsky, R.A., Zalischak, B.L., Sapin, V.I.: Petrology and Platinum Content of Ring Alkaline-Ultrabasic Complexes, 381 p. Nauka Publishing, Moscow (1994). (in Russian) Orlova, M.P.: Geological structure and genesis of the Kondyor ultramafic massif. Tihookeanskaya geologiya [Pac. Geol.] 1, 80–88 (1991) Burg, J.-P., et al.: Translithospheric mantle diapirism: geological evidence and numerical modeling of the Kondyor zoned ultramafic complex (Russian Far-East). Petrol. J. 50(2), 289–321 (2009) Cabry, L.J., Laflamme, J.H.G.: Platinum group minerals from the Konder massif, Russian Far East. Mineralog. Rec. 28, 97–106 (1997)

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Mochalov, A.G., Khoroshilova, T.S.: The Konder alluvial placer of platinum metals. In: International Platinum, pp. 206–220. Theophrastus Publications, Athens (1998) Shcheka, G.G., Lehmann, B., Gierth, E., Gömann, K., Wallianos, A.: Macrocrystals of Pt – Fe alloy from the Kondyor PGM placer deposit, Khabarovskiy kray, Russia: trace-element content, mineral inclusions and reaction assemblages. Can. Mineral. 42, 601–617 (2004)

Compositional Zoning of Spessartine-Grossular Garnets in the Archean Metavolcanics of the Central Bundelkhand Greenstone Complex, Bundelkhand Craton, Indian Shield O. S. Sibelev(B) Karelian Branch of the Russian Mineralogical Society, Institute of Geology, Karelian Research Centre RAS, Petrozavodsk, Russia [email protected]

Abstract. The paper deals with the peculiarities of the chemistry and internal structure of garnet from the Archean metavolcanites of the Mauranipur structure of the Central Bundelkhand greenstone complex. Garnet in them is stable during a long metamorphic evolution and naturally changes its composition from almandine-spessartine, to grossular, associating with amphibole (composition from pargasite and chermakite, to grunerite-cummingtonite and actinolite), clinopyroxene, chlorite, zoisite-clinocoisite, kalishpate, etc., In the final stages it is in equilibrium with calcite, albite, prenite, etc. pumpellite. In some garnet grains, a contrasting complex chemical zonality is formed with sharp zone boundaries and changes in the mineral composition of inclusions across zones. The number of zones (three) is comparable to the number of epigenetic stages. Due to the contrast of the BSE images of the garnet (due to the inverse dependence of the FeO and CaO contents), the character of zoning is considered, stringers, “interzone anomalies” and inclusions of grossular garnet in spessartin-almandin are identified. Garnet grains are not always a closed system and they can undergo processes of recrystallization of inclusions. Keywords: Archean · Metamorphism · Garnet · Garnet zoning · Stringers · Bundelkhand craton · Indian shield

1 Introduction Undoubtedly, one of the most informative minerals for determining the modes of endogenous processes of their changes and the sequence of epigenetic events is garnet. In the greenstone rocks of the Central Bundelkhand greenstone complex (CBZK), it is quite rare and far from ubiquitous. There are only isolated finds of garnet in the Mauranipur structure (Slabunov and Singh 2021; Sibelev 2020). This paper presents the results of studies of the garnets identified by the author, the garnet-containing mineral associations, the features of the chemistry and internal structure of this mineral, which, in the author’s opinion, are of petrological significance. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 223–231, 2023. https://doi.org/10.1007/978-3-031-23390-6_28

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2 Geological Sketch The Bundelkhand craton consists mainly of Neoarchean microcline granites (Ramakrishnan and Vaidyanadhan 2010; Singh et al. 2019), among which there are large fragments of decompressed tonalite-trondyemite-granodiorites estimated to be 3.59–3.2 billion years old (Kaur et al. 2016). The Meso-Neoarchean Central Bundelkhand (CBPC) and South Bundelkhand greenstone complexes play an important role in the craton structure (Singh and Slabunov 2015, Singh et al., 2019, 2021). The CDZK is composed of the Babin and Mauranipur belts and its exits are traced from west to east for about 150 km (Fig. 1a). The early association of the Mauranipura belt CDP is composed of three strata: (1) ultrabasite-basalt (metaultramafites and metabasalts) (Fig. 1b); (2) rhyolite-dacite (felsic metavolcanites); and (3) ferruginous quartzites (BIF). The Late one is a subvolcanic body of acidic volcanics. The contacts between the strata are tectonic (Slabunov and Singh 2021). The age of early acidic volcanics is 2813 ± 20 Ma, metasomatites are 2687 ± 17 Ma, and dikes of felsic rocks (late association) are 2542–2557 Ma (Singh and Slabunov 2015; Slabunov and Singh 2021). Paleoproterozoic hydrothermal processes have been observed in the area, during which giant quartz veins have formed (Ramakrishnan and Vaidyanadhan 2010; Pati et al. 2007; Slabunov and Singh 2021, 2022). The

Fig. 1. a. Layout of the Central Bundelkhand Terrane (modifided after Slabunov and Singh 2021) Symbols: 1-alluvial deposits; 2- Vindhyan Supergroup; 3-terrane boundaries; 4-Bundelkhand granitoids; 5-greenstone complexes; 6-TTG complexes. b. Diagram of the geological structure of the greenstone belt in the Mauranipur district of the Bundelkhand craton (modifided after (Slabunov and Singh 2021; Sibelev et al. 2021a, 2021b). Symbols: 1 – alluvial deposits; 2 – quartz veins (reefs) (1.9–1.8 Ga); 3–7 – greenstone complex: 3 – dike of felsic rocks (2.56 Ga), 4 – banded iron formation (BIF), 5 – felsic metavolcanites (2.81 Ga), 6 – metabasalts (sometimes with relics of pillow texture), 7 – metaultramafites and high – magnesium basal rocks; 8 – metasomatic rocks (ca 2.7 Ga); 9 – granitoids (3.55–2.5 Ga); 10 – sampling points and their number; 11 – estimated faults (a) and thrusts (b); 12–14 – occurrence elements: 12 – banding, 13 – shale and linearity, 14-overturned occurrence.

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age of the early stage of their formation is estimated at 1866 ± 12 Ma, and the late stage-1779 ± 43 (Slabunov et al. 2017; Slabunov and Singh 2022). Three stages of epigenetic transformations are distinguished in metavolcanites (Sibelev et al. 2021a, 2021b): 1) Neoarchean (about 2.7 Ga) metamorphism with a peak at the level of the amphibolite facies of increased pressures (T – 580–680 °C, P – 7.2–10 kbar); 2) regressive metamorphism with an assumed P-T-t trend "clockwise", associated with intense Ca-metasomatosis, and 3) Paleoproterozoic (1.9–1.8 Ga) metamorphism of the prehnite-pumpellite facies (T – 150–250 °C, P – 3–5 kbar).

3 Working Methods During fieldwork, more than 60 samples of metavolcanites were selected to study metamorphic processes. Preference was given to the selection of metamorphic and metasomatically altered rocks containing superimposed minerals and mineral associations. The problem of mineral paragenesis isolation was solved with the help of detailed petrographic studies and paragenetic analysis. The analysis of the chemical composition of minerals was performed on a scanning scanning electron microscope TESCAN VEGA IILSH with the prefix INCA Emergency 350, combined with a microanalyzer in the analytical center of the Institute of Geology of the KarSC RAS, Petrozavodsk (analyst A. N. Ternovoy). The calculation of mineral formulas from weight oxides of elements to crystallographic formulas was performed using the program Minal 3.0, created by D. V. Dolivo-Dobrovolsky (Institute of Precambrian Geology and Geochronology of the Russian Academy of Sciences (IGGD RAS).

4 Petrography Garnet is a typomorphic mineral for metamorphic rocks and is recorded in metamafiteultramafic and acidic metavolcanites. At high-temperature stages of transformation in both types of protolith, it occurs together with metamorphogenic clinopyroxene (diopside). Also, as index minerals, amphiboles of a wide range of compositions are associated with garnets: from low-siliceous pargasites and cermakites, through hornblende, to cummingtonites-grunerites and actinolites. The chlorites are represented by pycnochlorite and clinochlorite, and the minerals of the epidote group are zoisite and clinocoisite. Acidic metavolcanites, initially rocks of allotriomorphic-grained (aplitic), with areas of porphyritic microstructure, characterized by the presence of plagioclase and polycrystalline (recrystallized) quartz inclusions, up to 1 mm in size, against the background of a fine-grained (0.05–0.15 mm) bulk of quartz-feldspar (±Amp, Ms, Chl, Mag) composition. Under the influence of superimposed processes, the primary structural and textural features of rocks are obscured, and are described in terms of metamorphic petrography as gneisses of nematogranogranoblast, porphyrogranoblast structures, with a plane-parallel or banded texture. The mineral composition of acidic metavolcanites depends not so much on the variations in the composition of the protolith, but on the nature and intensity of the superimposed, especially metasomatic transformations.

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Metaultramafites are represented by altered olivine clinopyroxenites (Malviya et al. 2006), clinopyroxenites, and possibly websterites (one of the samples recorded relics of orthopyroxene and cummingtonite pseudomorphoses on it). In the selected samples, olivine was not recorded, but pseudomorphoses of aggregates of ore minerals of rounded shape, which could be formed by olivine, were noted. Metaclinopyroxenites are characterized by a coarse-grained (3–5 mm) panidiomorphic-grained structure and a massive texture. In addition to amphibole, they crystallize garnet, chlorite, clinocoisite and other secondary minerals. Rocks acquire first poikilite or mosaic, then – nematoblast and nematogranoblast structures. Under intensive, relatively low – temperature transformations, cummingtonite, amphiboles of the actinolite series, and, sometimes in significant quantities, chlorite develop. The derivatives of this process are medium-grained actinoliths and garnet-amphibole chloritites. Early metamorphic parageneses are represented by: Grt-Prg-Pl; Cpx-Prg-Pl; CpxGrt-Pl; Cpx-Prg (±Ksp, ± Qz, ± Mag). The regressive stage is traced in the sequential change of parageneses: Grt-Pl-Hbl; Grt-Chl-(Hbl-Act); Grt-(Zo-Czo)-(Hbl-Act); GrtChl-Pl (±Ksp, ± Qz, ± Mag, ± Ms). The late stage of metamorphic transformations occurs in the prehnite-pumpelliite facies, with parageneses: Prh-Pmp-Alb; Prh-Pmp-Grt; Pmp-Grt-Alb; Prh-Cc-Act; Prh-Grt-Cc.

5 Chemical Composition, Zoning and Internal Structure of Pomegranates Macroscopically, the pomegranate grains are colored in different colors, but the color relationship with the chemical composition is not revealed. Grain sizes rarely exceed 1 mm. Their number is small and rarely exceeds 2–3 grains per cut. Garnets crystallize in the form of isometric, poikilite, and often – case-shaped grains and have a noticeable anisotropy (they are illuminated in crossed nichols), which is characteristic of the grossular-andradite varieties of this mineral. According to the chemical composition, the studied garnets belong to the pyralspite (Prp-Alm-Sps) and partially to the granitic (Grs – Adr) series (Godovikov 1983; Grew et al 2013) (Fig. 2). They are characterized by high concentrations of spessartin minal (up to 44%), low-pyrope components, and colossal variations in the contents of almandine and grossular minal both in the general sample and within individual grains. In some analyses, small amounts of shorlomite (up to 0.83% TiO2) and uvarovite (up to 0.16% Cr2O3) minals are detected. Almost all studied grain of garnets possesses contrasting zonation (Fig. 3). In the most high-temperature areas at low concentrations and a slight hesitation Cao, marked inverse correlation between Prp and Alm minals with regressive orientation (fall and increase in MgO FeO). Changes in MnO contents are not natural. In the intermediate and, especially, in the marginal zones, with a sharp increase in the Grs content of the minal, both MgO, FeO, and sometimes – MnO have a direct correlation with each other, and their contents fall, compensating for the increase in CaO. The zones have clear boundaries with sharp differences in the content of components, which indicates a sharp change in the mode of epigenetic processes.

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Fig. 2. Component (nominal) composition was analyzed garnets from rocks CBSC Bundelkhand craton (a) in the coordinates of spessartine (Sps) – almandine (Alm) – andradite grossular (Grs Adr), with dedicated fields of pyralspite (Pir) and rangitoto (Grn) series (Godovikov 1983; Grew et al. 2013).

Numerous cracks splitting grenades or its individual zone, made by chlorite, potassium feldspar, prehnite or late calcium garnet. In the latter case, they are interpreted as stringers. Prenite cracks, unlike the others, cut not only the garnet grains, but also the matrix. In the BSE images, in the largest pomegranate grains, three zones are clearly distinguished (Fig. 3a). By the number of zones, we can judge at least two sharp changes in the parameters of the superimposed transformations. The central zones of the garnets were formed within the metamorphism of the amphibolite facies, with a regressive intra-zone sequence of changes in the chemical composition. Intermediate zones can be associated with a regressive stage or metasomatic changes. The marginal zones are interpreted as areas that crystallize either under the influence of metasomatosis or metamorphism of the prehnite-pumpelliite facies. The latter assumption is supported by the fact that the garnets of the marginal zones are in equilibrium with prenite and pumpellite. At the boundaries of the zones, darker areas are often observed – “interzone anomalies” (Fig. 3a), characterized by a higher content of grossular minal and a lower content of almandine, relative to the contents of these components in the zone containing them. The same three zones can be observed not only in the whole garnet, but also in areas with grain defects in its peripheral corroded part (Fig. 3b). Such zoning, in fact, can be interpreted as a giant double stringer-a crack healed by late generations of garnet. At least two generations of stringers have been identified in the grenades. The largest number of them dissects the central parts of the grains, but some are traced to the intermediate zones. In the borders, the stringers are often not visible, since the component composition of the garnet stringers is close to the composition of the marginal zones that contain them. The profile distribution of components in stringers is similar to the distribution of components by zones (Fig. 3b). These observations indicate that the formation of stringers began at the relatively early stages of blastesis, simultaneously with the growth of the garnet, and was regressive.

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Fig. 3. Back-scattered electron (BSE) images of fragments of pomegranate seeds and profiles of the concentration distribution of the main indicators of the composition and with growth zoning and “radiative anomalies”; b - stringencoding zonation in the peripheral area of the grain (b).

Based on the nature of the curves of the concentration distribution of components on the profiles through stringers, contacts of zones or inclusions of garnet in garnet, knowing the temperature of metamorphism at this stage and the diffusion coefficients of the components, it is possible to calculate the duration (chronometry) of the metamorphic process (Perchuk 2003). In the case of the processes under consideration, this task does not seem relevant, but judging by the “smoothness” of the profiles of the component contents, it can be concluded that the grenades were subjected to thermal effects for a long time after the formation of the stringers. In CBPC garnets, the chemical composition of the inclusions is very close to the composition of the edge zones of the grains and the central parts of the stringers. This indicates that these inclusions cannot be relict in any way, since their chemical composition correlates with the most recent phases of crystallization and are often directly connected to stringers. Figure 4 clearly shows that the late (Grt III) grossular secretions are not essentially inclusions, but products of pseudomorphic substitution of the present

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inclusions, in this case, chlorite and epidote, initially crystallizing along their periphery. Attention should also be paid to the presence of pumpellite as "inclusions", the temperature stability range of which, with a regular regressive change of parageneses, is significantly lower than the stability limit of the almandine-spessartin garnet that contains it. The most logical explanation for this is the pseudomorphic crystallization of pumpellite inside a garnet grain.

Fig. 4. BSE images of fragments of garnet grains illustrating: a-the contrasting zoning and distribution of inclusions in different zones, b - the processes of pseudomorphic substitution of chlorite and epidote inclusions by late garnet generations.

Thus, these garnets in the physico-chemical aspect are not a closed system and in the inner parts of the grains, recrystallization processes could occur not only of calcium garnet, but also of other minerals. Microcracks and stringers contributed to this process and served as channels for fluid filtration and the introduction and removal of components. The conditions of the “open physico-chemical system” of garnet explain the formation of the so-called interzone anomalies. With the observed sharp change in the parameters of metamorphogenic-metasomatic processes at the zone boundary and the probable time pause of blastesis during this change, the boundaries of the garnet zones can be considered as the boundaries of grains of different minerals, for example, garnet and amphibole. In these zones, for some time, there are intergranular (interzone) channels through which fluids seep and lead to regular changes in the composition – an increase in the calcium content of the garnet, a drop in iron content and, as a result, the formation of such “anomalies”.

6 Conclusion Garnets of metavolcanites of the Central Bundelkhand greenstone complex, have unique features of chemical composition and correspond to the almandine-spessartine-grossular

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series, are characterized by contrasting, complex, zoning. They were formed under conditions of long evolution, under the influence of discretely manifested metamorphic and metasomatic processes (Ca metasomatosis), and are stable in the range from amphibolite facies to high-pressure metamorphism to prehnite-pumpelliite facies. The inverse dependence of the iron and calcium contents in the considered garnets makes its images in the reflected electrons contrasting, which allows us to better understand the general laws of the internal structure, growth or diffusion zonality, internal heterogeneity of the composition, shape and features of the development of stringers, etc. In the studied garnets, at least two generations of stringers and a large number of "inclusions" of grossular in almandine-spessartine and in spessartine-grossular were revealed, which would not be visible with other compositions. Pomegranate seeds are not always a closed system. In some cases, the processes of recrystallization and replacement of inclusions inside garnet grains with later minerals, substitution in mineralized cracks, the formation of "interzone anomalies" and the crystallization of garnet with a chemical composition corresponding to later generations are observed. Acknowledgments. “The work was carried out with the financial support of the RFBR (grant 17-55-45005 IND-a), is a contribution to the implementation of the state task of the KarSC RAS (IG KarSC RAS, project A18-118020290085-4).”

References Godovikov, A.A.: Mineralogy. 2nd edn, reprint and additional M, 647 p. Nedra (1983). (in Russian) Grew, E.S., Locock, A.J., Mills, S.J., , I.O., Galuskin E.V., Hålenius, U.: Nomenclature of the garnet supergroup. Amer. Mineral. 98, 785–811 (2013) Kaur, P., Zeh, A., Chaudhri, N., Eliyas, N.: Unravelling the record of Archaean crustal evolution of the Bundelkhand Craton, Northern India using U–Pb zircon–monazite ages, Lu–Hf isotope systematics, and whole-rock geochemistry of granitoids. Precambrian Res. 281, 384–413 (2016) Malvia, V.P., Arina, M., Pati, J.K., Kaneko, Y.: Petrology and geochemistry of metamorphosed basaltic pillow lava and basaltic komatiite in the Mauranipur are: subduction related volcanism in the Archean Bundelkhand craton, Central India. J. Mineral. Petrol. Sci. 101, 199–219 (2006) Pati, J.K., et al.: Geology and geochemistry of giant quartz veins from the Bundelkhand Craton, Central India and their implications. J. Earth Syst. Sci. 116, 497–510 (2007) Ramakrishnan, M., Vaidyanadhan, R.: Geology of India, 556 p. Geological Society of India (2010) Perchuk, A.L.: Petrology and mineral chronometry of crustal eclogites. Dissertation for the degree of Doctor of Geological and mineralogical Sciences. [Petrology and Mineral Chronometry of Crustal Eclogites. D.Sc Dissertation (Geology-Mineralogy)], 333 p., Moscow (2003). (in Russian) Sibelev, O.S.: Spessarttine-grossular garnets of metavocanics from the central Bundelkhand greenstone complex of the Bundelkhand craton, Indian shield: parageneses, zoning, stringers and inclusions. Trans. Kar. Res. Centre Russ. Acad. Sci. (2), 34–54 (2020). (in Russian) Sibelev, O.S., Slabunov, A.I., Mishra, S., Singh, V.K.: Metamorphism of the central Bundelkhand greenstone complex, Indian shield: mineral compositions, paragenesises, and P-T Path. Petrology 29(4), 404–438 (2021)

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Slabunov, A.I., Singh, V.K.: Crustal evolution of Bundelkhand craton in Archean and comparison with other Indian cratons. In: Shandilya, A.K., Singh, V.K., Bhatt, S.C., Dubey, C.S. (eds.) Geological and Geo-Environmental Processes on Earth. SNH, pp. 39–48. Springer, Singapore (2021). https://doi.org/10.1007/978-981-16-4122-0_4 Singh, V.K., Slabunov, A.: The central Bundelkhand Archean greenstone complex, Bundelkhand craton, central India: geology, composition, and geochronology of supracrustal rocks. Int. Geol. Rev. 57(11–12), 1349–1364 (2015). https://doi.org/10.1080/00206814.2014.919613 Singh, V.K., Slabunov, A.I., Nesterova, N.S., Singh, M.M., Bhatt, S.C.: Tectonostratigraphic terranes of the Bundelkhand craton (Indian shield). In: Shandilya, A.K., Singh, V.K., Bhatt, S.C., Dubey, C.S. (eds.) Geological and Geo-Environmental Processes on Earth. SNH, pp. 155–164. Springer, Singapore (2021). https://doi.org/10.1007/978-981-16-4122-0_10 Singh, P.K., et al.: Geochemistry and Sm-Nd isotope systematics of metabasalts from the Babina and Mauranipur greenstone belts, Bundelkhand craton: implications for tectonic setting and Paleoarchean mantle evolution. Lithos. 330–331, 90–107 (2019) Slabunov, A.I., Singh, V.K.: Meso-neoarchaean crustal evolution of the Bundelkhand craton, Indian shield: new data from greenstone belts. Int. Geol. Rev. 61(11), 1409–1428 (2019). https://doi.org/10.1080/00206814.2018.1512906 Slabunov, A., Singh, V.K.: The new tectonic division of the Bundelkhand craton Indian shield. Trans. A. Fersman Sci. Session Geol. Inst. Kola Res. Centre RAS 16, 521–524 (2019) Slabunov, A.I., Singh, V.K.: Giant quartz veins and rift basins-indicators of Paleoproterozoic crustal destruction of cratons in northern India. Stages of Formation and Development of the Proterozoic Crust: Stratigraphy, Metamorphism, Magmatism, Geodynamics. Materials of the VI Ros. Conference on Problems of Geology and Geodynamics of the Precambrian, St. Petersburg, IGGD RAS, pp. 213–215. “Svoe Publishing House”, St. Petersburg (2019). (in Russian) Slabunov, A.I., Singh, V.K.: Giant quartz veins of the Bundelkhand craton, Indian Shield: New Geological Data and U-Th-Pb Age. Minerals 12, 168 (2022). https://doi.org/10.3390/min120 20168 Slabunov, A.I., Singh, V.K., Shchiptsov, V.V., Lepekhina, E.N., Kevlich, V.I.: A new Paleoproterozoic (1.9–1.8 Ga) event in the crustal evolution of the Bundelkhand Craton, India: the results of SHRIMP dating of zircons from giant quartz veins. In: Slabunov, A.I., Svetov, S.A., Baltibaev, Sh.K. (eds.) Early Precambrian vs Modern Geodynamics, Extended Abstracts and Field Trips Guide, pp. 239–241. KarRC RAS, Petrozavodsk (2017) Whitney, D.L., Evans, B.W.: Abbreviations for names of rockforming minerals. Amer. Mineral. 95, 185–187 (2010)

Anomalous Composition of Zircon from Leucogranites of the Belokurikhinsky Massif, Altai S. G. Skublov1,2(B) and M. E. Mamykina2 1 Saint-Petersburg Branch of the Russian Mineralogical Society, Institute of Precambrian

Geology and Geochronology RAS, Saint-Petersburg, Russia [email protected] 2 Saint-Petersburg Branch of the Russian Mineralogical Society, Saint-Petersburg Mining University, Saint-Petersburg, Russia

Abstract. For the leucogranites of the Belokurikha massif, depletion of LREE and HFS elements was established as a result of fractionation of the granite melt while maintaining the unchanged content of LIL elements. High content of rareearth elements (up to 87800 ppm) and Y (up to 50000 ppm) was found in zircon from leucogranite. The anomalous composition of zircon from leucogranites confirms the assumption that a late magmatic fluid rich in fluorine, saturated with incompatible elements, was formed during the evolution of the magmatic system of the Belokurikha massif. Keywords: Zircon · Leucogranites · Belokurikhinsky massif · Gorny Altai

1 Introduction The gabbro-granitoid massifs of the Belokurikha complex are distributed within various structural and formation zones of the Altai Mountains, which are associated with W-Mo skarn, W-Mo greisen and vein mineralization, Be pegmatite, Ta-Nb and Li mineralization. The formation of the massifs occurred as a result of mantle-crustal interaction and with varying degrees of assimilation of crustal material. Granitoids of the Belokurikha complex are classified as shoshonite granites (SH-type), which are characterized by mineragenic specificity with the manifestation of deposits of a wide range of rare metals (Gusev et al. 2008). The Belokurikhinsky massif is developed in the Anui-Peschanaya interfluve and has an area of about 500 km2 . The massif is located among the Ordovician-Devonian rocks of the carbonate and terrigenous-carbonate formations. As part of the Belokurikha massif, there are 3 phases of introduction: 1) melanogranites and granodiorites; 2) biotite granites; 3) biotite and two-mica leucogranites, moderate-alkaline leucogranites. Vein formations are represented by ore-bearing pegmatites (Gusev et al. 2008). The composition of granitoids is characterized by increased concentrations of potassium, and reduced concentrations of femic elements and calcium. The rocks belong to the highpotassium series of normal or slightly increased alkalinity, are characterized by increased ferruginousness, and are supersaturated with alumina (Kruk et al. 2018). © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 232–237, 2023. https://doi.org/10.1007/978-3-031-23390-6_29

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2 Factual Material and Research Methods For the study, zircon was separated from leucogranites (mod. TN3-1, Pl-Fsp-Ms-Qz) of the Belokurikha massif, recently uncovered during the construction of a road to the resort of the same name. The chemical composition of zircon by the major elements, the features of its internal structure, as well as the control of the presence of mineral phase inclusions in zircon and their composition were performed in the BSE mode by the SEM-EDS method (JEOL JSM-6510LA with EDS JED-2200, IPGG RAS, analyst O. L. Galankina). The content of REE and trace elements in zircon from leucogranite was determined by the SIMS method on the Cameca IMS-4f ion microprobe (YAP FTIAN, analysts S. G. Simakin, E. V. Potapov) according to standard methods. The primary beam of O2 − ions reached the surface of the sample at an angle of 25° relative to the normal, with an energy of approximately 14.5 keV, and focused into a spot with a diameter of 25– 30 µ. The current intensity of the bombarding ions was 3–4 nA. The area of collection of secondary ions was limited by the field of view set by the field aperture and the setting of the secondary ion optics, and was about 20–25 µ in diameter, which, along with the focusing of the primary beam, determined the locality of the analysis. When forming the analytical signal, a range of secondary ion energies of 75–125 eV was used, for which a bias of 100 V was applied to the sample under the base potential of 4500 V, and the energy gap was limited to 50 eV. The change in the potential of the analyzed region associated with the charging of the sample under the action of ion bombardment was corrected by using a special procedure for automatic tuning of the sample potential. The mass spectral resolution was M/M = 500. When constructing the REE distribution spectra, the composition of zircon from leucogranite is normalized to the composition of CI chondrite.

3 Results The leucogranites of the Belokurikha massif are represented by rocks of light-white to light-gray color and fine-grained structure. A sample of leucogranite of the third phase of TN3-1 was taken from the contact zone of the second and third phases of granitoids (51°58  08.09” N, 84°53 39.48” E, at an altitude of 670 m). The rocks of the second and third phases are clearly distinguished at the macro level: the second phase of granites has a medium-grained structure, medium-sized grains of quartz and plagioclase (0.1–0.8 cm) are observed in the rock, the rock is characterized by a yellowgray color with small (0.1–0.3 cm) grains of a dark mineral-biotite and ilmenite, which is formed when biotite is replaced by secondary minerals (chlorite, epidote). The third phase of granitoids is characterized by a light gray color, since there are no grains of dark-colored minerals in the composition of leucogranites. Pegmatite veins were found within the contact zone. At the contact of the third phase and the vein, the appearance of pale pink medium-sized (0.05–0.1 cm) grains of garnet – spessartin was observed. For leucogranite, a granite structure and a massive texture are determined. The average size is observed (0.75–0.5 mm) hypidiomorphic plagioclase grains, amounting to about 20 vol.%. Plagioclase grains contain inclusions in the form of small grains of muscovite and quartz (0.1–0.05 mm). Potassium feldspar is represented by medium and small in

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size (0.5–0.25 mm) microcline, its amount in the rock reaches about 40 vol.%. Quartz occurs in the form of xenomorphic grains (on average 30 vol.%). Muscovite grains are hypidiomorphic and occupy 5 vol.%. Among the accessory minerals, there are small grains (0.1–0.05 mm) of topaz, apatite, and fluorite, as well as medium and small-sized grains of garnet (0.5–0.25 mm). Secondary changes are practically absent, with the exception of feldspar, on which sericite is formed. Potassium feldspar is subject to the pelitization process. When studying the composition of the rock, it was noted that leucogranite belongs to the calcareous-alkaline group and is characterized by a moderate content of alkalis and corresponds to a high-K series (Na2 O + K2 O up to 9 wt.% and K2 O up to 6 wt.%). The content of trace elements in leucogranite is about an order of magnitude less than in phase 2 granites. For HFS elements, there is a significant decrease in the content of elements by several orders of magnitude during the transition from the second to the third phase. LIL elements (Rb, Cs, Ba, Sr) are characterized by a change within the same order (Cs 7–14 ppm; Rb 200–323 ppm; Ba and Sr 4–86 ppm). The content of Th in leucogranites is 1.7–6.7 ppm, Zr-8–22 ppm, Hf-0.7–1.7 ppm, Y-5–14 ppm. The distribution spectrum of rare-earth elements in leucogranite is flat, with a low LuN/LaN ratio of 0.7. The total content of rare-earth elements in leucogranite is 77 ppm, less than the sum of rare-earth elements in phase 2 granite (up to 242 ppm). When studying the distribution spectrum of rare earth elements (Fig. 1), a decrease in LREE was observed in leucogranite compared to the content in phase 2. The HREE content does not differ between phases. There is a negative Eu-anomaly (Eu/Eu* = 0.1). This distribution of elements shows that fractionation of the granite melt occurred during its evolution and the removal of minerals-concentrators of the corresponding elements from the system.

TN3-1

Rock/Chondrite

phase 2

Fig. 1. Distribution of rare-earth elements in granites of the Belokurikha massif

Zircon grains from leucogranite have a size not exceeding 100 µ, are opaque and differ in brown color. Most of the grains are rounded, with the exception of a few elongated grains. Zircon grains are characterized by a zonal structure, which is observed in the cathodoluminescence mode. This zoning in the grains is associated with a change in the composition. The central zones are characterized by a low LREE content (on average

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152 ppm), relative to the average LREE content for granitoids (Belousova et al. 2002), and the marginal zones show an increase in the LREE content (on average 1112 ppm). The HREE content continues to grow from the central to the marginal zone (1284 and 4036 ppm, respectively). In the BSE image, the zircon grains show a dark hue of varying degrees of intensity. According to the content of impurity elements, one grain is sharply distinguished (Fig. 2), which is an accretion with xenotimum (an elongated zone of light color with a thickness of 10–20 µ in the central part of the grain). The maximum number of impurities was found in a nodule with a diameter of about 20 µ of dark gray color in BSE (analysis point 21Dre). The total REE content (according to 4 ion microprobe assays) varies from 38251 to 87874 ppm (the average content is 21969 ppm). The REE spectra are moderately differentiated (the LuN / LaN ratio is on average 29). The Ce anomaly is practically absent (the value of Ce/Ce* is on average 1.27). In zircon, a negative Eu anomaly is shown (Eu/Eu* on average 0.23). Among the non-granular impurity elements, the maximum content is noted for Y (from 7947 to 49945 ppm with an average content of 27922 ppm). The average content of Ca is 3727 ppm, Ti-888 ppm, Sr-57 ppm, Nb-1122 ppm, Ba-80 ppm, Li-84 ppm. The Th and U content varies significantly (from 611 to 6620 ppm and from 6621 to 13232 ppm, respectively), which is reflected in the fluctuations of the Th/U ratio (from 0.05 to 1.00). The Hf content is extremely high (on average, 34565 ppm). If zircon enriched in Hf, U, Th is relatively common, then significant deviations in the content of Y and REE are less known. The Y content is usually in the range from 10 to 5000 ppm, the total REE content is from 100 to 2500 ppm (Harley and Kelly 2007). An abnormally high REE content was found in zircon from the metasomatites of the unique Oklo uranium deposit area, Equatorial Africa (98200 ppm, Horie et al. 2006) and in zircon from the pegmatite vein of the Gridino area, White Sea mobile belt (96800 ppm, Skublov et al. 2011). On the Fennoscandian shield, an abnormally high REE content was recorded in zircon from the metabasites of the Kontokki dike complex, the Kostomuksha structure (29800 ppm), lamproites of the Panozero sanukitoid complex, Central Karelia (55300 ppm), and quartz syenites in the central part of the North Karelian greenstone belt (89100 ppm). In the above-mentioned examples, as in the zircon considered in this paper, REE are concentrated in local domains and zones of change of zircon grains, which are characterized by a contrasting dark color in the BSE image. High Y content (up to 5 wt. % Y2 O3 ) was detected in zircons from the Dalradian complex meta-sediments in Scotland, formed during intensive fluid processing of rocks (Hay and Dempster 2009). An anomalous high Y content was found in zircon formed from a fluid-saturated syenite melt at the late magmatic stage of the Zr-Y – REE formation of the Azov field (Ukrainian Shield), when the role of fluids enriched in Y, REE, and Nb increased, which was directly reflected in the anomalous geochemical characteristics of the rims and zones of zircon change, the Y content reached 61874 ppm, REE reached 27667 ppm, and Nb reached 7976 ppm (Levashova et al. 2015, 2016). In zircon from the Tor Lake rare earth deposit (Canada), the total REE content of about 74000 ppm and the Y content of about 31500 ppm were determined (Hoshino et al. 2013).

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Fig. 2. Image of zircon grains from leucogranites of the Belokurikha massif, indicating the analysis points (left part of the figure); REE distribution spectra for these points, normalized to CI chondrite (right part of the figure).

All the above-mentioned examples of anomalous zircon composition from rocks of different composition and age are united by the influence of fluids enriched with incompatible elements (HFSE and REE), which are usually immobile during igneous and metamorphic processes. Usually, the inclusion of Y and REE (mainly HREE) in the zircon composition is explained by an isomorphism of the xenothymic type (Y + REE)3+ + P5+ = Zr4+ + Si4+ . Such an isomorphism scheme assumes a proportional increase in the content of Y and HREE on the one hand, and P on the other. But for the considered zircon from the leucogranites of the Belokurikha massif, the increase in the P content significantly lags behind the increase in the Y and REE content. It is possible to assume that in this case the isomorphism of the xenothymic type has a subordinate value, and the predominant is the isomorphism according to the scheme: H+ + (REE, Y)3+ = Zr4+ . The P content is in the range of 2122–7795 ppm (Table 1), which unambiguously cannot provide for the occurrence of trivalent REE and Y according to the xenothymic isomorphism scheme. Table 1. Content of trace and rare earth elements in zircon from leucogranites of the Belokurikha massif, ppm Point

LREE

HREE

7863

1033

21D2

27185

21D3

14576

21Dre

38251

21

REE

P

Ca

Y

Nb

Th

U

6564

2122

1017

7947

278

611

4277

21557

4897

4344

34095

1569

4299

6765

2053

11813

7279

7279

19703

307

309

10586

5601

30693

7795

7795

49946

2333

6620

6621

13232

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4 Conclusion For the leucogranites of the Belokurikha massif, depletion of LREE and HFS elements was established as a result of fractionation of the granite melt while maintaining the unchanged content of LIL elements. High content of rare-earth elements (up to 87800 ppm) and Y (up to 50000 ppm) was found in zircon from leucogranite. The anomalous composition of zircon from leucogranites confirms the assumption that a late magmatic fluid rich in fluorine, saturated with incompatible elements, was formed during the evolution of the Belokurikha massif magmatic system (Gusev et al. 2008).

References Gusev, A.I., Gusev, N.I., Tabakaeva, E.M.: Petrology and ore content of the Belokurikha complex of Altai, 197 p. BPSU named after V. M. Shukshin, Biysk (2008) Kruk, N.N., Kuibida, M.L., Gavryushkina, O.A., Kruk, E.A., Kuibida, Ya.V.: Evolution of granitoid magmatism in long-lived centers of magmatic activity (on the example of the North-Western Altai). Petrology of igneous and metamorphic complexes. Issue 10. In: Materials of the X AllRussian Petrographic Conference with International Participation, pp. 202–206. Publishing House of the Tomsk Central Research Institute, Tomsk (2018) Levashova, E.V., et al.: Zircon geochemistry and U–Pb age at rare metal deposits of syenite in the Ukrainian Shield. Geol. Ore Deposits 58(3), 239–262 (2016) Levashova, E.V., et al.: New data on zircon geochemistry and age (U-Pb, SHRIMP II) of the Yastrebetskoe Zr-REE-Y deposit, Ukrainian Shield. Geochem. Int. 53(6), 572–579 (2015) Skublov, S.G., Marin, Yu.B., Galankina, O.L., Simakin, S.G., Myskova, T.A., Astafyev, B.Yu.: The first discovery of abnormal (Y+REE)-enriched zircons in rocks of the Baltic Shield. Dokl. Earth Sci. 441(2), 1724–1731 (2011) Belousova, E.A., Griffin, W.L., O’Reilly, S.Y., Fisher, N.L.: Igneous zircon: trace element composition as an indicator of source rock type. Contrib. Mineral. Petrol. 143, 602–622 (2002) Harley, S.L., Kelly, N.M.: Zircon tiny but timely. Elements 3(1), 13–18 (2007) Hay, D.C., Dempster, T.J.: Zircon behaviour during low-temperature metamorphism. J. Petrol. 50, 571–589 (2009) Horie, K., Hidaka, H., Gauthier-Lafaye, F.: Elemental distribution in zircon: alteration and radiation-damage effects. Phys. Chem. Earth, Parts A/B/C 31, 587–592 (2006) Hoshino, M., Watanabe, Y., Murakami, H., Kon, Y., Tsunematsu, M.: Formation process of zircon associated with REE-fluorocarbonate and niobium minerals in the Nechalacho REE deposit, Thor Lake, Canada. Resource Geol. 63, 1–26 (2013)

Chrome-Spinelides from Layered Intrusions of the Paleoproterozoic Fennoscandian Shield as Indicators of Petro - and Ore Genesis V. F. Smolkin1(B) and A. V. Mokrushin2 1 Moscow Branch of the Russian Mineralogical Society, V.I. Vernadsky State Geological

Museum RAS, Moscow, Russia [email protected] 2 Kola Branch of the Russian Mineralogical Society, Federal Research Centre Kola Scientific Centre of the Russian Academy of Sciences, Apatity, Russia [email protected]

Abstract. A comparative study on compositions of accessory and ore chromespinelides of the harzburgite-orthopyroxenite-gabbronorite-anorthosite layered intrusions (Monche- and Burakov plutons, Imandra Complex, Kemi, Penikat, Akanvaara, Koitelainen), Pados dunite-orthopyroxenite massif, as well as Paleoproterozoic lherzolite-gabbronorite massifs (“Drusite Complex”) deposited within the Kola region, Karelia, and Finland was carried out. Compositions of mineral phases were studied by X-ray spectrometry using MS-46 CAMECA (GI KSC RAS, Apatity) and CAMECA SX50 (Nancy, France) electron microprobe analysers. The phases were diagnosed based on the author’s minal classification diagram that takes into account a Ti admixture. In composition of ore chrome-spinelides, two groups of ore intrusions were identified, i.e., with more chromic (Kemi, Monche- and Burakov plutons) and more ferruginous (Imandra Complex, Koitelainen) chrome-spinelide. Compositions of ore and accessory chrome-spinelides are rather similar in some intrusions (Imandra Complex) and differ drastically and consistently in others (Monche- and Burakov plutons, Penikat). Composition of accessory chrome-spinelides is highly dependent on rock composition and regulated by changes in composition of evolving melts and increasing oxygen fugitiveness (dlogfO2 (QFM) = −4 to 1.8). Keywords: Fennoscandian Shield · Paleoproterozoic · Layered intrusions · Chromite deposits · Minal classification of chrome-spinelides · Accessory and ore chrome-spinelides

1 Introduction Chrome-spinelides are major ore phases of chrome deposits and most common accessory minerals of products of komatiite, picrite, and basalt magma crystallization. Their chemical composition is one of the highly-sensitive physical-chemical indicators of melt crystallization. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 Y. Marin (Ed.): GMRMS 2021, SPEES, pp. 238–246, 2023. https://doi.org/10.1007/978-3-031-23390-6_30

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In this work, results of the comparative study on composition of ore and accessory chrome-spinelides of chromite ore deposits, their enclosing and overlaying rocks composing Paleoproterozoic layered intrusions deposited in the eastern Fennoscandian Shield within the Kola region, Karelia, Central and Northern Finland are given. The study also includes data on the Pados dunite-orthopyroxenite massif containing a chromite mineralization, and massifs of the “Drusite Complex” in the West White Sea region, which are deep analogues of the layered intrusions, but formed under moving frame conditions.

2 Methods of Analysis Compositions of the mineral phases are studied by X-ray spectroscopy using MS46 CAMECA (Geological Institute of the KSC RAS, Apatity) and CAMECA SX50 (National Centre for Scientific Research CRPG-CNRS, Nancy, France) electron microprobe analysers. The Pados massif structure was studied on a sample basis using Xray diffraction methods on the DRON-2.0 and automated DRON-4.0 diffractometers (Petrozavodsk State University). Apart from the author’s data (Table 1), literary sources were used. Chrome-spinelides (spinel group minerals) have a variable composition forming continuous series of solid divalent (Fe2+ , Mg2+ ) and trivalent (Al3+ , Cr3+ , Fe3+ ) cation solutions with a large extent of isomorphic substitutions. Chrome-spinelides classifications by N.I. Pavlov (1979) and T.N. Irvine (1965, 1967) are the most popular. The first classification is a triangular diagram based on isomorphic substitution of trivalent cations; the second one is a prism with ratios of divalent and trivalent cations. Yet, both classifications do not take into account the role of Ti, whose high contents were initially found in the lunar soil and consequently in the Earth’s rocks, as well as in gabbro-wehrlite intrusion and the Pechenga ferropicrite volcanics (Smolkin 1992). Admixtures of Ti, as

Fig. 1. Minal classification diagram for spinel group minerals. After (Smolkin 1979) with simplifications.

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well as of Mn, Ni, V, and Zn, are continuously present in chrome-spinelides of layered intrusions. All mineral species forming chromite-spinel, chromite-magnetite, chromiteulvöspinel isomorphic series are shown in the author’s minal diagram (Fig. 1). We use the author’s classification to characterise chrome-spinelides. Magnochromite (50–65% Cr2 O4 ), chrompicotite (35–55% Cr2 O4 ), and alumochromite (35–50% Cr2 O4 ) are major industrial minerals. Table 1. Composition of ore chrome-spinelides from layered intrusions of the Kola region, Karelia, and Finland, the Stillwater intrusion and Kempirsay Complex, wt% (sampling) Oxides 1 MgO

2

3

10.48 10.08 2.46

4

5

6

7

8

0.98

0.79

13.24 10.28 15.87

Al2 O3 8.36

7.32

14.06 11.52 10.59 7.89

13.50 13.84

TiO2

1.00

0.10

0.47

1.22

0.50

0.06

0.10

0.37

Cr2 O3 54.77 54.49 47.96 49.87 51.31 60.09 49.59 52.21 FeO

22.05 23.76 31.40 35.64 34.67 13.19 22.44 15.43

NiO

0.24

0.25

0.03

0.02

0.03

0.13

0.23

0.22

MnO

0.64

0.68

0.46

0.52

0.52

0.12

0.78

0.53

ZnO

0.20

0.10

0.09

0.13

0.23

0.00

0.19

0.10

Sum

97.95 97.68 96.55 99.17 98.19 94.82 97.68 98.56

Oxides 9 MgO

10

13.44 10.92

11

12

13

14

15

16

11.14 12.34 14.18 12.53 14.93 6.37

Al2 O3 14.08 11.54

11.47 11.83 11.90 11.78 11.74 11.41

TiO2

0.07

0.51

0.14

0.10

0.12

0.07

0.16

0.16

Cr2 O3 52.93 58.80

60.00 59.82 60.53 59.50 58.64 35.34

FeO

16.85 18.34

15.83 14.76 12.78 13.97 13.48 45.37

NiO

0.19

0.08

0.18

0.16

0.18

0.15

0.14

0.07

MnO

0.47

0.19

0.04

0.12

0.04

0.18

0.00

0.89

ZnO

0.00

0.04

0.06

0.02

0.00

Sum

98.48 100.05 98.73 99.17 99.73 98.23 99.18 99.58

0.04

Oxides 17

18

19

20

21

22

MgO

7.71

6.81

3.85

6.61

15.66 15.66 15.51

8.32

23

24

Al2 O3 10.37 11.85 10.06 0.43

10.46 11.79 12.11 11.39

TiO2

0.33

0.12

0.61

0.24

0.48

0.20

0.20

0.16

Cr2 O3 53.69 50.54 50.81 42.24 53.69 55.73 55.60 55.94 FeO

24.26 25.14 27.25 48.61 25.18 13.98 14.09 14.11

NiO

0.00

0.03

0.63

0.27

0.11

0.19

0.12 0.19 (continued)

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Table 1. (continued) Oxides 17

18

19

20

21

22

23

24

MnO

1.17

1.20

0.66

1.62

0.95

0.69

0.58

0.57

ZnO

0.00

1.30

1.82

0.53

0.50

0.00

0.00

0.00

Sum

97.92 98.38 98.28 98.02 98.53 98.24 98.35 97.86

Note. 1, 2 – Burakov pluton: 1 – densely and 2 – sparsely disseminated ore; 3, 4, 5 – Imandra Complex (Bolshaya Varaka deposit): 3, 4 – densely disseminated ore in norite, 5 – banded densely disseminated ore; 6 – Kempirsay Complex, massive ore; 7–15 – Monchepluton (Sopcheozero deposit): 7, 8, 15 – rich ore, 9 – banded ore, 10 – supraore dunite, 11, 12 – rich ore with sideronitic texture, 13, 14 – rich massive ore with disseminated olivine deposits; 16–21 – Pados massif (third ore horizon): 16, 17, 21 – chromite ore, 18, 19, 20 – lower contact, middle part, and upper contact; 22–24 – Stillwater intrusion, massive ore. Collection and analyses of V.F. Smolkin, analytics Ya.A. Pakhomovsky, S.A. Rezhenova

3 Brief Geological-Petrological Characteristic The layered intrusions are composed of a series of harzburgite–orthopyroxenitegabbronorite-anorthosite rocks (Alapieti et al. 1990; Sharkov and Smolkin 1998). They are spatially confined to Paleoproterozoic volcanogenic-sedimentary structures, one of which, the Pechenga-Varzuga Belt, is the largest palaeoriftogenic system (Smolkin 1997). Within the layered intrusions, there are deposits of chromite, sulphide Cu-NiPGE, low-sulfide Pt-metallic, and Ti-V ores. The intrusion occurred according to data on the study of isotope U-Pb, Sm-Nd, and Re-Os systems (Amelin et al. 1995, 1996; Bayanova et al. 2014; Huhma et al. 2018, and others) in two stages: before the PechengaVarzuga Belt was deposited (2.52–2.48 Ga) and later (2.45–2.43 Ga) affected by intense base and medium-alkaline volcanism due to the uplift of two heterochronous mantle plumes, which are spatially shifted in relation to each another (Smolkin et al. 2009). Within the Western White Sea region (Karelia), lherzolite-gabbronorite massifs (“Drusite Complex”) (2.46–2.43 Ga), which are analogues of the layered intrusions, are deposited. Deposits of industrial chromite ores occur in the Kemi intrusion (Finland), nonindustrial chromite mineralisation occurs in the Penikat, Akanvaara, and Koitelainen intrusions (Finland), Burakov pluton (Karelia), Monchepluton and of the Imandra Complex massifs, as well as in the Pados dunite massif with the age of 2.48 Ga (Kola Peninsula). Nowadays, one of the best-investigated deposits is the Sopcheozero deposit occurring within the Monchepluton dunites (Smolkin et al. 2004; Chistyakova et al. 2016; Barkov et al. 2021; Mokrushin and Smol’kin V.F. 2021).

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4 Analysis and Discussion The diagram (Fig. 2) shows major trends in changes of accessory chrome-spinelide composition in different magmatites. Phases with a maximum enrichment in Cr3+ (i.e., chromite) are only found in meteorites and as microinclusions in kimberlite diamonds. Alumochromite is typical of Archaean komatiites. The Cr3+ – Al3+ trend is typical of dunite-harzburgite chrome-spinelides and basalts of ophiolite complexes. Such a trend is also defined for the Outokumpu Paleoproterozoic Complex (Finland). Ore chromite of the Kempirsay Complex (Table 1) has the highest Cr2 O3 content. Complex trends are found for layered intrusions (Bushveld, Stillwater, Great Dyke, Sarany massif): initially Cr3+ – Al3+ , then Cr3+ – Fe3+ . Analogous trends are also found for the studied intrusions. The Norilsk picrites and the Pechenga ferropicrites continue these trends, and the Guli massif titanomagnetites close them. Individual trends are formed by meymechites, subalkaline basalts, and low-titanium picrites of peninsula Kamchatka. Monchepluton is taken as a reference layered intrusion, where a full set of rocks and ore deposits occurs in the structure, including the Sopcheozero chromite deposit. Within Monchepluton, chromium, aluminium, and magnesium contents of chromespinelides decrease with a simultaneous increase in Fe2+ + Fe3+ content (Fig. 3) from the Sopcheozero dunites to harzburgites, orthopyroxenites, and gabbronorites. The analogous situation could be observed in the Penikat and Burakov pluton from peridotites to

Fig. 2. Trends of changes in composition of chrome-spinelides from various magmatites and meteorites in the Pavlov’s diagram. After (Smolkin et al. 2004) as amended and augmented. 1 – meteorites; 2 – Outokumpu ophiolite Complex; 3 – dunite-harzburgite Complex; 4 – oceanic basalts; 5 – inclusions in kimberlites; 6–7 – layered intrusions, Sarany massif (6) and Bushveld Complex (7); 8 – Kytlym massif, dunite-clinopyroxenite Complex; 9 – meymechites; 10 – Guli massif, Bor-Uryakh; 11 – inclusions in subalkaline basalts; 12 – Kamchatka picrites; 13 – Pechenga gabbro-wehrlite Complex; 14 – Norilsk region intrusions; 15 – plateau-basalts.

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orthopyroxenites. The general trend is disturbed by accessory chrome-spinelides from the Penikat intrusion gabbronorites with a low content of Fe3+ .

Fig. 3. Composition of accessory and ore chrome-spinelides of Paleoproterozoic layered intrusions of the Fennoscandian Shield in the Irvine’s diagram. Ore: 1 – Bolshaya Varaka (Imandra Complex); 2 – Sopcheozero deposit (Monchepluton); 3 – Penikat; 4 – Kemi; 5 – Koitelainen; 6 – Akanvaara. Accessory: 7 – Imandra Complex; 8 – Monchepluton; 9 – Penikat; 10 – Akanvaara.

Accessory chrome-spinelides from the Imandra Complex norite have typical higher ferrum and magnesium contents and relatively low contents of Al2 O3 and Cr2 O3 . From norites and gabbronorites to gabbro, a content of Cr2 O3 and MgO decreases in them, and titanomagnetite crystallised in the preroof area. This trend of accessory chromite composition changes derives from intense accumulation of Fe and TiO2 in the residual melt, which substitute Cr2 O3 and Al2 O3 and form continuous solutions. A content of Fe3+ increases simultaneously with a decrease in a content of chromium and aluminium in chrome-spinelide, which indicates that the melt crystallised within the Imandra Complex massifs under hyperoxidative potential conditions. Ore chromite layers are found on different layers of general sections of the layered intrusion: on bottom layers composed of dunites, peridotites, and orthopyroxenites (Monche- and Burakov plutons, and Kemi) and upper layers mainly composed of norites and gabbronorites (Imandra Complex, Koitelainen). The Sopcheozero deposit ore chrome-spinelides have the highest magnesium and chromium contents. They coexist with high-magnesium olivine (98–96% Fo) with a high content of Ni (up to 1.1 wt%). Ore chrome-spinelides confined to peridotites and orthopyroxenites (Kemi, Penikat, Koitelainen, and Akanvaara) differ by a lower content of Cr2 O3 and higher ferruginosity, alternatively, ore chrome-spinelides deposited in norites and gabbronorites of the Imandra complex has highest ferruginosity and contain an increased TiO2 admixture (mean content 1.2 wt%). The chrome-spinelides crystallised under open system conditions, where oxygen fugitiveness is relatively consistent (−4 to −2). Chrome-spinelides

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from gabbro-anorthosite areas of the Akanvaara and Koitelainen intrusions are also high ferriferous. Ore chrome-spinelides of the Pados massif occur as magnochromite with an increased content of MnO (up to 1.62 wt%) and ZnO (up to 1.82 wt%) admixtures (Table 1). They occur in the beginning of the trend typical of the Paleoproterozoic layered intrusions. Field of composition of accessory chrome-spinelides of the “Drusite Complex” partially overlapped by fields of compositions of Monche- and Burakov plutons chrome-spinelides (Fig. 4). Compositions of ore and accessory chrome-spinelides are rather similar in some cases (Imandra Complex) and differ drastically and consistently in other cases (Moncheand Burakov plutons, Penikat). A ratio of ore and accessory chrome-spinelides varies due to changes in composition of evolving melts and increase in oxygen fugitiveness, as well as ore mass recrystallisation with formation of honeycomb structure, which leads to disturbances in balance between chrome-spinelide and olivine. In the Imandra Complex massifs, ore and accessory phases has an intermediate composition between magnoalumochromite and alumochromite, typical high ferruginosity, and small variations in a Fe3+ content. Gradual shifts from accessory to ore phases indicate their similar formation conditions.

Fig. 4. Composition of chrome-spinelides of the “Drusite Complex” the West White Sea region (1), layered intrusions: Burakov pluton (2), Monchepluton (3), and the Imandra Complex massifs (4) in the Smolkin’s diagram.

In the Monche- and Burakov plutons, and Penikat intrusions, and ore phases occur as magnochromite, accessory phases found in all rock types occur as magnoalumochromite and alumochromite. They contain less Cr2 O3 and MgO, but more Al2 O3 . Using the example of the Sopcheozero deposit, it was identified that accessory chrome-spinelides have higher contents of ZnO admixture (mean 0.41 wt%) than ore chrome-spinelides (900, 800–890, and