Home – Home – Jornals – Russian Geology and Geophysics 2018 number Неопубликованное

Zones of hydrothermal vein-disseminated, disseminated sulfide, predominantly pyrite, mineralization in Riphean rocks of the Kyvvozhsky region are characterized by elevated contents of Au, Cu, Se, Mo, Ag, Pb, Bi, Sb, Zn. According to the results of the correlation analysis, the following groups of ore elements were identified, within which the strongest positive correlations were established: Ag-Bi-As-Со; Pb-Cu-Zn-Se; Co-Ni-As. Pyrite, arsenopyrite, chalcopyrite, galena, sphalerite, cobaltite, monazite, xenotime, bornite, and covellite are found in association with pyrite in sulfide veinlets. Native gold is rare; particles with peripheral low-grade zones alternate with high-grade gold overgrowths are present. Inclusions of pyrite, pentlandite, monazite, and albite are observed. The gold contains Ag, and sometimes Cu and Pd, as impurities. Judging by the relationships between the minerals, pyrite was the earliest, followed by pyrrhotite, chalcopyrite, and cobaltite, followed by sphalerite, galena, and gold. The formation of sulfide mineralization is associated with hydrothermal processes that occurred in pre-Middle Devonian times, associated with the activation of tectonic-magmatic processes. Geological data, the heavy isotopic composition of pyrite sulfur with a variation in δ³⁴S values from +15.8 to +23.6 ‰, suggest that the most important role was played by regional metamorphic processes that facilitated the mobilization and migration of hydrothermal solutions along faults with the borrowing of various components from the host rocks and subsequent crystallization of sulfides and gold. In some cases, the presence of Cu and Pd impurities in gold indicates a possible influence on the mineral-forming solutions of basic rocks or their partial depth nature as derivatives of basite-hyperbasite magmatism. The Kyvvozhsky district is of interest for primary gold deposits and merits continued exploration.