Mineralogical and lithological properties of Domanikites from the south-east of Tatarstan Republic

Abstract

The article was described main types of rocks – mudstones, carbonate-siliceous rocks, containing organic matter and carbonate breccia, based on detailed analysis of rock samples from Semiluksky horizons of Upper Devonian black shale formations, Volga-Ural region, Russian Federation. Different structures and texture features, mineral composition, and content of organic matter characterized selected types of rocks. Only in the carbonate-siliceous type of rocks is the high content of organic matter, about 9%. It was found direct dependence between the content organic matter and content in rocks silica minerals (quartz and chalcedony). Such dependence caused by joint precipitation silica minerals and accumulation of organic matter in the seafloor in conditions of active seepage of hydrothermal fluids. The presence of an abundance of biophilic elements in ascending fluids led to an explosion of biota and widespread of silica organisms. This hypothesis doesn’t disagree with any authors but considers the significant contribution of fluid factor to the deposition of Semiluksky formations.