Ore mineral formation stages of the Sredniy site (Mnogovershinnoye deposit)

Abstract

The Mnogovershinnoye gold deposit (Khabarovsk Territory, Russia) today is a significant industrial facility, which features extension additions as a results of additional in-mine exploration of deep horizons and identification of new objects within the ore field. The purpose of this work is to study the formation stages of ore minerals of one of the deposit sites as well as to identify the mineralogical and structural-textural features of ores. The methods of mineralogical and petrographic study of the material composition of ores are widely used in geological practice and allow to determine the material features of the studied objects as well as describe the ore formation process. The study of ore types was carried out using an Olympus BX51 microscope. Field observations performed by the authors served the base for the mineralogical and petrographic study of ore samples and host rocks of the Sredniy site of the Mnogovershinnoye deposit, which led to a slightly different understanding of formation stages of ore mineralization of this section of the deposit. The study revealed at least three formation stages of the material complex of this site of the deposit. The first stage is a magmatic one. It characterizes with the formation of pyrite of the first generation. The second stage is an ore hydrothermal one, as a result of which the gold-sulfide mineralization was formed including pyrite of the second generation, chalcopyrite, magnetite, kustelite. Gangue quartz was formed at the end of the second stage together with such ore minerals as pyrite, chalcopyrite, magnetite, and an insignificant amount of kustelite and native copper. The third stage is an exogenous one, during which substitution and oxidation structures were formed with iron hydroxide evolution. The studies of the ores of the Mnogovershinnoye deposit have shown once again the presence of polysulfide multistage mineralization, which had been developing in close connection with the magmatic process. Knowledge about the deposit formation stages is an integral part of the creation of geological and structural models of the deposit, which are necessary to increase the efficiency of geological exploration within the studied objects.