Geology and genesis of the Vantage Gold Deposits, Alligator Ridge-Bald Mountain mining district, Nevada

The geology and the major element and isotopic geochemistry of a group of Carlin-type Au deposits in the Alligator Ridge-Bald Mountain district of east-central Nevada were investigated to determine the origin of Au mineralization and associated alteration. These data were used to constrain a series of numerical simulations of the formation of the deposits.;The Vantage deposits were the largest of 18 known Carlin-type Au deposits and prospects in a district uncomplicated by Paleozoic thrusts or pre-mineralization intrusions. Au mineralization occurred adjacent to a normal fault at the contact between the Devonian Devils Gate Limestone and the Pilot Shale. Hydrothermal fluids ascended along the fault and produced an inner zone of decalcification and volume conservative silicification surrounded by an outer zone of dedolomitization. Au was restricted to zones of silicification and showed a strong preference for the Pilot Shale. Following Au deposition, an early oxidation event destroyed sulfides, organic matter, and detrital illite in the Pilot Shale and deposited alunite ;;Numerical modelling of deposit formation was performed to simulate mass transfer between source and deposit. Fluid compositions were calculated at 350...