MAGNESITE-BEARING STRATIFICATED LEVELS AND THEIR LITHOLOGICAL NATURE IN THE RIPHEAN DOLOMITE SEQUENCES OF THE SOUTHERN URALS

Abstract

Three stratificated levels of magnesite-bearing dolomites—Lower Riphean (Bakal-Satka-Suran), Middle Riphean (Avzyan), and Upper Riphean (Min’yar)—are recognized in the Riphean section of the Bashkir Anticlinorium of the southern Urals. Dolomites contain submicroscopic (∼1 μm) magnesite dissemination (MgO/CaO > 0.714). The Lower and Middle Riphean magnesite-bearing dolomites host metasomatic magnesite stocks, lenses, pockets, and large stratiform lodes formed as products of hydrothermal activity. No metasomatic magnesite bodies are known in areas without indications of the hydrothermal reworking of magnesite-bearing dolomites. Magnesite deposits of the southern Urals are typical elisional-hydrothermal products related to sedimentation and lithogenesis of carbonate rocks in isochemical system of sedimentary basin. Juvenile components did not participate in the formation of magnesite deposits in the southern Urals.