Mineralogy and Cu-Au-Bi ore paragenesis of Kuh-e Dom prospecting area (northeastern Ardestan), Anarak metallogenic province

Modeling based on equilibrium thermodynamic and physicochemical condition suggests that Bi-rich melts can efficiently scavenge Au from hydrothermal fluids, even if these fluids are highly undersaturated with respect to Au minerals. At this study the Kuh-e Dom prospecting area in northeastern of Ardestan city (northern part of Anarak metallogenic province) as the prominent sample of Iron Oxide Cu-Au (IOCG) hyrothermal deposit have been investigated by quartz-hematite-sulfide mineralization accompanied with Fe-Cu-Au assemblage. The fahlor-group sulfosalt minerals, Bi-minerals and trace metals (e.g., gold, bismuth and electrum) investigated due to achievement of chemical composition and genetic relation to Au mineralization. Au scavenging occurs efficiently by Bi-minerals such as bismuthinite (B2.05S2.9), emplectite (Cu0.56Fe0.03Bi1.2S2.16), and native bismuth (Cu0.14Bi0.86). Evidence shows release electron from reduced minerals (e.g., pyrrhotite) and consequently increase of fluid oxygen have been eventuated Bi3+ to Bi0 and precipitation of bismuth. Hence, with occurrence of magnetite as the stable buffer phase the release electron involves reduction Au+ to Au0 and adsorbed by bismuth minerals.