Gold-sulfide (Au-As) Deposits of the Yenisei Ridge (Russia): Age, Sources of Metals and Nature of Fluids

The problem of orogenic gold deposits genesis is considered in this contribution under the example of the Olympiada orogenic gold deposit in Yenisei Ridge, Siberia (Russia). The main productive arsenopyrite mineralization was deposited at 689 +/- 28 Ma (Re-Os), postdated by later berthierite-stibnite mineralization, deposited at 672.7 +/- 4.1 Ma (Ar-Ar). Main stage of mineralization correlates with intrusion of alkaline mafic rocks of the Zahrebetinskiy complex which was formed within the interval of 703-696 Ma (Ar-Ar). The age of antimony mineralization coincides with the age of the Chapinskiy alkaline picrite-carbonatite complex (670-650 Ma). Similar age for the gold-sulfide mineralization is established at other deposits of the Yenisei Ridge. The involvement of magmatic fluids from concurrent mafic alkaline, alkaline granite and granitoid melts in ore genesis is supported by fluid inclusion studies. The isotope-geochemical characteristics (Pb, Os, He, and S) of gold-arsenopyrite, gold-polysulfide, and stibnite-berthierite parageneses of ores at the Olympiada deposit suggest that different isotopic reservoirs could have served as the sources of ore material and fluids.