Exploration geology of the Golden Arrow gold-silver district, Nye County, Nevada

The Golden Arrow district is located along the northern margin of the Walker Lane and on the western rim of the Oligocene Kawich Mountains caldera. Principal elements of the geologic framework include: (1) pre-caldera andesite, overlain by (2) rhyolite ash-flow tuff from the Kawich volcanic center. Both units are cut by (3) a caldera-margin fault with bonanza quartz-adularia-gold veins. Straddling the caldera-margin lies the tilted block of (4) Confidence Mountain rhyolite ignimbrite, interpreted as a collapse block along the caldera margin. Extending northwestward from Confidence Mountain is a structural depression with (5) volcaniclastic rhyolite-dominant moat sediment. Epithermal volcanic-rock-hosted Au-Ag mineralization occurs in two distinct styles. Low-sulfidation epithermal quartz-adularia-gold veins fill open faults and fault-breccia. Disseminated hot-springs-style mineralization overprints earlier veins within pre-caldera andesite and rhyolite volcaniclastic sediment. Two deposits-Gold Coin and Hidden Hill-have been defined by exploration drilling. Within these, gold mineralization is disseminated in breccia zones with intense clay-pyrite alteration surrounding vitrophyre dikes, and gold is concentrated in near-horizontal stratabound chalcedony layers within volcaniclastic sediment. Modeling of gravity data reveals a prominent gravity high interpreted to be caused by a high-density intrusive body at depth. Upward apophyses coincide with latite dikes within the known deposit.