Skarn Alteration and Mineralization at Coroccohuayco, Tintaya District, Peru

摘要: Coroccohuayco is a porphyry-related copper skarn deposit in the Andahuaylas-Yauri batholith of southeast Peru with little evidence for presence significantly mineralized hydrothermal system at surface. The occupies hinge zone synform, hosted by Cretaceous Ferrobamba Formation. Hydrothermal alteration carbonate protolith produced between underlying hornfels-altered Mara Formation and an overlying preskarn sill-like diorite intrusion, main mineralization generally below 200 m from spatial distribution was dominantly controlled permeability variations protolith. consists prograde garnet-dominant calc-silicate chalcopyrite-bornite ± chalcocite disseminated as grains calc-silicates. Precious metal occurs gold silver minerals mostly associated bornite-chalcocite within more distal granular garnet alteration. Fluids were derived crystallization several porphyry phases that intruded into upper crustal level, possibly cupola above batholith. Fluid inclusion data pyroxene indicate formed 400° to >600°C highly saline fluids. Data quartz 250° 400°C, magnetite deposition over part this range. Retrograde (+carbonate-silica) replacement calc-silicates locally mineralization. Hydrous retrograde alteration, commonly observed other systems, lesser importance Coroccohuayco. This likely related geochemical effects intrusion which could have impeded influx oxidized meteoric waters or buffered composition late-stage fluids, well Fe-rich character skarn.