Geological Setting and Gold–Bismuth Mineralization of the Namovskoe Deposit (Southern Sikhote-Alin)

Abstract

Based on the results of a comprehensive geological, mineralogical, and geochemical study of ores of the Namovskoe deposit, new data on the specifics of mineralization were obtained. The ores of the deposit were formed in close relation to the Early Cretaceous monzonitoid magmatism against the background of active left-hand movements along the Middle Sikhote-Alin fault. The U–Pb dating of the ore-bearing dyke provided an age of 103 Ma. In addition to native Au, the ores of the deposit contain high concentrations of Ag, Bi, and Cu. A variety of Bi minerals were registered in the ores: sulfide (bismuthinite), telluride (hedleyite), sulfotellurides (tetradymite, joseite-А, and joseite-В), Ag sulfobismuthite (matildite), Pb–Bi sulfosalts (aschamalmite, cannizzarite, cosalite, lillianite, nuffieldite, and galenobismuthite), an intermetallic compound of Au (maldonite), and native Bi. Ag minerals were identified as well: chloride (cerargyrite), sulfide (acanthite), and telluride (hessite). The typomorphic patterns of ore minerals and the geological structure of the Namovskoe deposit assign it to the type of gold deposits formed in a transform continental margin setting. A mantle source of ore mineralization is suggested.