Cerro Casposo, sistema epitermal de baja sulfuración en el área de Villa Corral, Calingasta, San Juan, Argentina

SOTARELLO, GUSTAVO; BELVIDERI, IRMA; MACHUCA, EDUARDO; CASTRO DE MACHUCA, BRÍGIDA

Mendoza

Otro; Curso Latinoamericano de Metalogenia UNESCO-SEG 2004; 2004

UNESCO-SEG (Society of Economic Geologists)

The gold-silver mineralization at Cerro Casposo, is hosted within numerous multiphase epithermal quartz-adularia-calcite±illite-sericite-sulphide veins, breccias and stockworks associated with tensional faulting and hydrothermal brecciation in a pyroclastic-volcanic sequence (rhyolite to andesite) of Permo-Triassic age (Choiyoi Group). Mineralization occurs scattered over 20 km2 area of extensive propylitic alteration. Silicification and argillitization halos up to tens of meters wide are parallel to the main veins. Mineralization occurs predominantly along sub-vertical to steeply west-southwesterly dipping, northwest-southeast, north-south and east-west striking structures. The ore minerals include gold, native silver, electrum, acanthite, argentotetrahedrite, low silver-bearing tetrahedrite, silver sulphosalts and lesser amounts of stromeyerite, iodargyte, cervelleite and hessite, associated with polymineralic aggregates of fine-grained disseminated pyrite and minor sphalerite, chalcopyrite, galena and locally, arsenopyrite, digenite and luzonite (?). Oxidation has reached depths of more than 50 meters within veins and fault breccias. A recent K/Ar age from adularia of 280±9 Ma was obtained from a quartz-adularia vein. Estimate open pit mineral resources (indicated+inferred categories), using gold equivalent cut off of 1.4 g/t are 2.743.000 tons grading 4.135 g/t gold and 104.14 g/t silver, totaling 467.800 oz gold equivalent.