ИСТИНА

Geological structure, metasomatic rocks, and ore mineralogy indicate that the Sentyabr’sky deposit is related to the porphyry-epithermal system (Simmons et al., 2005). The ore mineralogy corresponds to the IS type of Silitoe and Hedenquist (2003). The assemblage of Te minerals identified in the Sentyabr’sky ores is typical of many Au-Te epithermal deposits. However, various Au tellurides are characteristic of the ores from these deposits, whereas only one Au telluride petzite was found in the ores of the Sentyabr’sky deposit. At the same time, according to computation, 40-70% Au in the Au-Ag-Te ores at the Sentyabr’sky deposit occur as petzite. It is probable the new type of the Au-Te mineralization transitional from shallow- to deep-seated ores. According to fluid inclusion data, the Sentyabr’sky ores started to precipitate at higher temperature (about 300oC) than low-sulphidation Au-Ag mineralization of the Dvoinoi deposit (257oC, after Prokofiev et al., 2012). Based on mean gradient of hydrostatic pressure (100 bar/km), the Sentyabr’sky ores can be formed at the depth ca. 1 km. The salinity of mineralizing fluids of the Sentyabr’sky and Dvoinoi deposits is dramatically different. A similar picture is seen at the Au-Ag and Au-Te epithermal deposits (Simmons et al., 2005). The Au-Ag-Te mineralization of the Sentyabr’sky deposit and low-sulfidation Au-Ag mineralization of the Dvoinoi deposit are resulted from different hydrothermal fluids, which are related to the different phase of magmatic activity. The Sentyabr’sky deposit was formed as a part of multistage porphyry-epithermal system with different types of mineralization and the transition of epithermal to porphyry mineralization with depth is suggested. According to classification of Silitoe (2010), the Sentyabr’sky deposit may be referred to the subepithermal type.