Askold Gold Deposit (Askold Island, Primorye, Russia): Physicochemical Parameters and Composition of Ore-Forming Fluids

Individual fluid inclusions in quartz from ore veins of the Askold gold deposit, which was previously attributed to the epithermal type, are studied for the first time. It is established that gold mineralization of Askold Island derived from ore-forming fluids of carbon dioxide–water–salt composition, with a salt concentration of 2.8–4.1 wt % NaCl equiv and a high carbon dioxide concentration, at temperatures of 280–324°C and pressures of 1240–2170 bar. The tectonic control of gold mineralization, the presence of tin and bismuth minerals in the ores, the high fineness of gold, and the characteristics of the mineral-forming fluids (primarily high pressures) indicate that the Askold deposit can be attributed to the type of gold deposits associated with granitoid intrusions.