Sulfur Isotope Composition and Geochemical Characteristics of Gold-Bearing Sulfides from the Badran Orogenic Deposit, Yana–Kolyma Metallogenic Belt (Northeast Asia)

The sulfur isotope composition of pyrite and arsenopyrite collected at various hypsometric levels (from 587 to 970 m) from quartz–sericite–carbonate–pyrite–arsenopyrite metasomatic rocks of the Nadvigovaya mineralized zone of the Badran orogenic gold deposit was analyzed by the local method. The geochemical characteristics of sulfides were studied. The narrow range of δ 34 S for pyrite (from –0.7 to +1.9‰) and arsenopyrite (from –1.1 to +0.3‰) indicates that the elements were formed during a single evolving hydrothermal event. Two types of pyrite were identified: isotopically and geochemically heterogeneous with an increase in the values of δ 34 S from the center to the edges of the grains and a synchronous decrease in the As concentrations, and a homogeneous type. Pyrite and arsenopyrite contain structurally bonded gold; arsenopyrite with about zero values of δ 34 S is characterized by a higher gold content. The assessment of the correlation of the sulfur isotope composition of pyrite and arsenopyrite with depth showed the presence of a nonlinear vertical isotope–geochemical zoning due to the heterogeneity of hydrothermal–metasomatic changes in the Nadvigovaya mineralized zone of the Badran deposit.