Fluid-rock interactions within Paleoproterozoic Au mineralization of the Sakoli Group, India

摘要

Au mineralization occurs in the Palaeoproterozoic Sakoli Group of rocks in central India associated with quartz-sulfide ± carbonate veins within the metavolcano-sedimentary sequence of the southern block of the Central Indian Tectonic Zone (CITZ). The mineralization is focused predominantly within the E-W trending major shear zone correlated with the regional schistosity (S_2) plane. Gold occurs both as invisible and native forms with other polymetallic associations. The mineralization exhibits both lithological and structural controls and is associated with pervasive alteration resulting from intensive ore-fluid-rock interaction, which produced considerable mass and volume changes near the shear zone. The fluid inclusion study reveals that the fluids responsible for gold mineralization are approximated by the H_2O-NaCl-CO_2 ± CH_4 system. The system appears to have evolved from a carbonate dominated regime to an increasingly aqueous dominated regime through time.