Pyrrhotite–Nisbite–Breithauptite–Sulfoantimonide Micromineral Assemblage: a Product of High-Temperature Recrystallization of Ores at the Yuzhnoe Vein-Type Tin–Silver–Polymetallic Deposit, Sikhote-Alin, Russia

• Published in: Geology of ore deposits 2021-12, Vol.63 (7), p.717-734
• Main Authors: Ratkin, V. V., Simanenko, L. F., Eliseeva, O. A., Gonevchuk, V. G.
• Format: Article
• Language: English
• Subjects: Antimony; Boundaries; Chalcopyrite; Chemical composition; Cretaceous; Crystallization; Earth and Environmental Science; Earth Sciences; Galena; Grain boundaries; Heavy metals; High temperature; Immiscibility; Inclusions; Liquidus; Mineral Resources; Minerals; Minerals and Mineral Parageneses; Miscibility; Nickel; Ores; Pyrrhotite; Recrystallization; Segregations; Silver; Temperature; Thermal transformations; Tin; Trace elements; Veins (geology)
• ISSN: 1075-7015; 1555-6476
• DOI: 10.1134/S1075701521070072

—The paper presents the results of mineralogical studies of tin–silver–polymetallic ores localized at the deep level (500–700 m below the surface) of the Yuzhnoe Cenomanian deposit. On the deep southwestern flank of vein no. 4, indications of ore recrystallization have been revealed. Mineral segregations (inclusions) with sharp boundaries and myrmekite texture as fine intergrowths of pyrrhotite with nisbite (NiSb 2 ) or breithauptite (NiSb) are found in recrystallized ores at the grain boundaries of nickel-bearing pyrrhotite and galena with abundantly disseminated Ag–Sb minerals. Less frequently, myrmekite-like segregations are pyrrhotite graphically intergrown with gudmundite or nonstoichiometric chemically variable Ag sulfoantimonide (phase X). Tiny grains of Ag-bearing chalcopyrite and stannite are frequently observed in pyrrhotite–sulfoantimonide intergrowths. The formation of myrmekite-like segregations is presumably associated with ore transformation in the fluid-thermal field of a Maastrichtian postore leucogranite intrusion. Local segregations of the mobilizate (mobile phase) formed as a metal-bearing sulfoantimonide melt during ore recrystallization at a temperature of ~600°C as a result of the redistribution and migration of trace elements to the contacts of mineral grains. Heterogenous distribution and variable chemical composition of micrographic segregations reflect immiscibility and differentiation of the formed metal-bearing sulfoantimonide melt during its liquidus evolution. The final avalanche-like quenching crystallization of melt inclusions was implemented below 300°C.