Формы нахождения металлов платиновой группы и их генезис в золоторудном месторождении Сухой Лог (Россия)

Abstract

A platinum group element (PGE) mineralization was discovered and studied in the unique Sukhoi Log stratabound gold deposit. The PGE mineralization is also stratabound and localized in both gold ores and the overlying metasedimentary rocks. Platinum dominates in ores among the other PGE, which have much lower concentrations. The modes of PGE occurrence are first established for deposits of this type. Native platinum and Pt-Fe-Cu solid solutions are the major platinum-bearing phases. Palladium tellurobismuthide was identified; rhodium was also found as a mineral phase. The PGE-bearing minerals are accompanied by a large number of native metals and metal solid solutions, such as native iron, chromium, tin, lead, nickel, tungsten, titanium, Fe-Cr-W and Ni-Sn-Sb solid solutions, and other phases. This paper contains new data on gold ore mineralogy and phase composition of organic matter. Based on the analysis of mineral assemblages as well as thermobarometric and isotope data, we concluded that PGE mineralization and associated native metals and metal solid solutions formed earlier than the gold ores. The reduced metal forms, including PGE, originated during hydrogen-induced reduction coupled with oxidation of hydrocarbons. The classification of the Sukhoi Log as a platinum-gold deposit is the main result of our study. The PGE behavior and formation of PGE-bearing phases in ores follow the general laws of migration and concentration of these elements in endogenous processes.