Gold-rich weathering rinds around pyrite and arsenopyrite near a Mo-Cu porphyry deposit in the Copper Basin, Nevada: implications for supergene enrichment and possible relationships with Carlin-style mineralisation

The Copper Basin is a well-endowed mineral camp with notable Mo, Cu, and Au mineralisation, located near Battle Mountain, Nevada, USA. Mo and Cu mineralisation is associated with the emplacement of Cretaceous granitic stocks and dykes, which produced local quartz stockwork veins. Tertiary granites produced skarn Au and Au ± Cu mineralisation. The study area lies within the Eureka mineral belt which hosts significant Carlin-style disseminated, sediment-hosted Au mineralisation. Several Tertiary granitoids in the northern part of the study area that were dated in this study had ages, ~41 – 37 Ma, correlating with the magmatism associated with the other intrusions along the Eureka Au trend. Petrographic studies of pyrite have found Au-rich weathering rinds around some pyrite grains sampled in, and near, the Buckingham porphyry. These supergene rims overprint the hypogene Au mineralisation.