Native copper formation associated with serpentinization in the Cheshmeh-Bid ophiolite massif (Southern Iran)

In the Cheshmeh-Bid district of Khajeh-Jamali ophiolitic massifs (Southern Iran), mantle peridotites are intruded by abundant pyroxenite dykes. A few these dykes remarkable for occurrence native copper associated with development a metasomatic reaction zone. The progressively reacted, from their margins towards center, an amphibole + antigorite selvage, followed centimeter-thick clinopyroxene assemblage and, finally, copper-bearing zone consisting chlorite antigorite. Native Cu occurs along cleavages and partially healed fractures in clinopyroxene, as massive grains intergrown Copper isotope signatures thermodynamic calculations show that main driver formation is Ca-metasomatism. forms at expense chalcocite Such can only occur reducing conditions, agreement analysis fluid inclusions composition displaying H2 CH4. fluids presumably originated hydration rocks. observed mineralization thus interpreted result Ca-metasomatism during hydrothermal alteration oceanic lithosphere. This consistent U/Pb dating titanite, suggesting Albian when were exposed on seafloor supra-subduction setting. source mineralization, revealed isotopes, probably mantle-like.