Mineralogy of black shale deposits in the Yluelga-Kudashmanovo zone (Bashkir Meganticlinorium)
This article contains information on the geological structure and mineralogical and petrographic composition of Middle Riphean black shale deposits confined to the Yuryuzan-Zyuratkul regional fault (Bashkir Meganticlinorium). It describes in detail the complex sulphide Au-Ag-U-Th-REE and quartz vein mineralizations studied with the use of modern precision equipment and thermobarometric geochemical techniques. With varying degrees of detail, the article describes sulphides (pyrite, pyrrhotine, chalcopyrite, sphalerite, galena), native elements (Au, Ag, Sn) as well as thorium-uranium and REE-phosphate mineralizations. Investigations into the quartz vein mineralization made it possible to identify several quartz generations, each characterized by its specific gas composition of fluid inclusions and total fluid content. The areas of gold, Au and Ag-containing and sulphide mineralizations within the Kudashmanovo section coincide with the zones of bluish grey quartz having fluid content of 50-100 µl/g. It is shown that complex black shale mineralization of the Uluelga-Kudashmano zone was formed at several stages. In summary, the genesis of complex mineralization within highly dislocated black shale strata of the Bashkir Meganticlinorium was caused by the regional geodynamic regime and can be characterized by a two-stage model. The first stage is "preparatory" riftogenic, during which the geochemical specialization of rocks and first-generation minerals took place. The second collisional (?) ore-forming stage is characterized by the development of regional metamorphism, water palingenesis in the crust and mineral formation under the conditions of the functioning fluid-hydrothermal system with varying parameters of the geochemical environment and thermobarometric features of the process.