Gold–Sulfide Mineralization in the Manitanyrd Region, Polar Urals, Russia

Abstract

This article describes the characteristics of gold–sulfide–quartz and gold–sulfide (gold–arsenic) ore occurrences in the Manitanyrd region of the Polar Urals. Ore occurrences are confined to NE-trending shear zones and have the common features of a geological structure. The host rocks are metamorphosed volcanic and volcanic–sedimentary rocks. We analyzed the mineral and chemical composition of the ore mineralization in all studied ore occurrences, showing that they belong to the same mineral type—pyrite–arsenopyrite, with a variable ratio of the main minerals. Arsenic pyrite is present in all ore occurrences. Two stages of ore formation were distinguished: early gold–pyrite–arsenopyrite with finely dispersed gold and late gold–galena–chalcopyrite–sphalerite with coarse gold, fahlore, and sulfosalts Pb, Cu, Bi, Sb. Native gold of the first generation, finely dispersed in arsenopyrite and pyrite, had an average to high fineness (800‰–1000‰) with a relatively low dispersion. Native gold of the second generation was larger, and its fineness in ore occurrences varied; in one of them, it varied from 300‰ to 950‰, while in others, it varied from 800‰ to 950‰. The isotope composition of sulfur in sulfides (δ34S) ranged between −0.2‰ and −8.0‰. δ34S values of sulfides in the range of −0.2‰ to −3.5‰ were similar to meteorite, indicating the participation of a single deep magmatic source of sulfur in the ore formation. According to the study of fluid inclusions, the formation of ore quartz veins occurs in the temperature range of 467–109 °C. The similarity of the geological–structural, mineralogical–geochemical, and isotope–geochemical features of the gold–sulfide–quartz and gold–sulfide occurrences in the area suggest their formation in a single hydrothermal system.