1. Native copper formation associated with serpentinization in the Cheshmeh-Bid ophiolite massif (Southern Iran)
- Author
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László Előd Aradi, Ryan Mathur, Alessandra Montanini, Claudio Marchesi, Alireza Eslami, Benjamin Malvoisin, Chunhui Li, Giulio Borghini, Giovanni Grieco, Donald W. Davis, Alessandro Cavallo, Csaba Szabó, Kei Ikehata, Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Agencia Estatal de Investigación (España), Eslami, A, Malvoisin, B, Grieco, G, Aradi, L, Marchesi, C, Cavallo, A, Montanini, A, Borghini, G, Mathur, R, Ikehata, K, Davis, D, Li, C, and Szabó, C
- Subjects
Ca-metasomatism ,010504 meteorology & atmospheric sciences ,Geochemistry ,Cheshmeh-Bid ophiolitic massif ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,serpentinization ,engineering.material ,Iran ,010502 geochemistry & geophysics ,Ophiolite ,01 natural sciences ,Mantle (geology) ,GEO/09 - GEORISORSE MINERARIE E APPLICAZIONI MINERALOGICO-PETROGRAFICHE PER L'AMBIENTE E I BENI CULTURALI ,Geochemistry and Petrology ,Titanite ,Fluid inclusions ,Chesmeh-Bid ophiolitic massif ,Metasomatism ,Native copper ,Amphibole ,0105 earth and related environmental sciences ,geography ,Pyroxenite ,geography.geographical_feature_category ,Serpentinization ,Geology ,Massif ,engineering ,pyroxenite - Abstract
We would like to thank the two anonymous reviewers, and the editor Marco Scambelluri for their constructive and valuable comments and suggestions on our manuscript. Valentina Batanova and Valerie Magnin (ISTerre) are thanked for their help during the electron microprobe measurements. We would like to express our sincere gratitude to local people in Khajeh-Jamali village and workers from the Fars Chromite Company. The work of L. E. Aradi and Cs. Szabo was supported by the ELTE Institutional Excellence Program (TKP2020-IKA-05) managed by the Hungarian Ministry of Human Capacities. The work of G. Grieco was supported by the Italian Ministry of Education (MIUR) through the projects "PRIN2017 -Mineral reactivity, a key to understand large-scale processes" (2017L83S77) and " Dipartimenti di Eccellenza 2018-2022". C.M.s research has been funded by project PID2019-111715GB-I00/AEI/10.13039/501100011033., In the Cheshmeh-Bid district of the Khajeh-Jamali ophiolitic massifs (Southern Iran), mantle peridotites are intruded by abundant pyroxenite dykes. A few of these dykes are remarkable for the occurrence of native copper associated with the development of a metasomatic reaction zone. The dykes are progressively reacted, from their margins towards the center, with an amphibole + antigorite selvage, followed by a centimeter-thick clinopyroxene + antigorite assemblage and, finally, by the native copper-bearing zone consisting of clinopyroxene + chlorite + antigorite. Native Cu occurs along cleavages and partially healed fractures in clinopyroxene, and as massive grains intergrown with antigorite. Copper isotope signatures and thermodynamic calculations show that the main driver for reaction zone formation is Ca-metasomatism. Native copper forms at the expense of chalcocite in the reaction zone. Such a reaction can only occur in reducing conditions, in agreement with the analysis of fluid inclusions composition displaying H-2 and CH4. Such fluids presumably originated from the hydration of mantle rocks. The observed reaction zone and native copper mineralization are thus interpreted as the result of Ca-metasomatism during hydrothermal alteration of the oceanic lithosphere. This is consistent with U/Pb dating of titanite, suggesting formation during the Albian when the dykes were exposed on the seafloor in a supra-subduction setting. The source for copper mineralization, as revealed by Cu isotopes, is probably mantle-like., ELTE Institutional Excellence Program TKP2020-IKA-05, Ministry of Education, Universities and Research (MIUR) 2017L83S77, Ministry of Education, Universities and Research (MIUR) PID2019-111715GB-I00/AEI/10.13039/501100011033
- Published
- 2020