Mineralogical features of gold of the Permian conglomerates of the Sololiy uplift of the Olenyok high (Northeastern Siberian platform)

Abstract

The article analyses the Typomorphic features of placer gold of conglomerates of the Ortokinskaya formation of the Early Permian age (P1or) of the Sololiy Uplift of the Olenyok high and modern channel alluvium of the Ortoku Eekit river, which drains these deposits. It is found that the extremely heterogeneous composition and complex inner structure are typical features of the vast majority of gold of the Permian conglomerates. There are several stages of different fineness (from 251 to 999 ‰) within a single gold particle and as a result, gold has a mosaic-block inner structure. It is proposed that such heterogeneity is formed due to epigenetic transformations of primary medium-grade gold in an intermediate reservoir of the Permian age, and also due to the influence of superposed hydrothermal mineralization with low-grade gold, related to the processes of the Mesozoic tectonomagmatic activation. The latter is indicated by the discovery of impregnated gold-sulfide mineralization in the Permian conglomerates. Ore mineralization is represented by gold, silver, pyrite, sphalerite, chalcopyrite, galena, argentite, native tin, and barite. Association mineralization to thin tectonic zones of conglomerate fragmentation suggests that superposed gold-sulfide hydrothermal mineralization of an impregnated type was formed as a result of manifestations of the Mesozoic tectonomagmatic activation, when gold-bearing hydrothermal solutions migrated in faults. It is determined that auriferous conglomerates of the Ortokinskaya formation of the Permian age were major sources of placer gold of modern alluvium in the studied part of the Ortoku Eekit.