Orogenic gold: Common or evolving fluid and metal sources through time

Orogenic gold deposits of all ages, from Paleoarchean to Tertiary, show consistency in chemical composition. They are the products of aqueous-carbonic fluids, with typically 5–20 mol% CO2, although unmixing during extreme pressure fluctuation can lead to entrapment of much more CO2-rich fluid inclusions in some cases. Ore fluids are typically characterized by significant concentrations of CH4 and/or N2, common estimates of 0.01–0.36 mol% H2S, a...