TO CONCEPTUAL BASIS OF DEVELOPMENT OF EARTH CRUST OF URALS
In the lower, middle, and upper sections of the Riphean, represented within the territory of the Bashkir uplift by the Burzyan, Yurmata, Karatau, and Arsha series, respectively, graben formations with their characteristic features accumulated. In the final Riphean, in the Igonin Formation of the Arsha Group, individuals of several ages were found in zircons of the metabasalt complex. But only the age group of 715-750 million years, according to V.I. Kozlov, then N.D. Sergeeva and others, according to the amount of rare earth elements, began to be considered derivatives of undepleted magma, which led to the split of the continent and the emergence of a mid-ocean rift. Subsequently, spreading contributed to the development of the Ural Ocean. An oceanic crust was formed, represented by an association of hypermafic rocks with deepsea sediments and the appearance of eruptions of the main composition of the tholeiitic type. The Vendian Asha Group is located on various underlying parts of the sections, including the Karatau Group, with significant erosion. It is probable that it was precisely at this time that the change in the geodynamic regime of extension to increasing compression took place, which was materially expressed by the accumulation of flysch rhythmites with olistostrome horizons in the second half of the section. The thrusting of the oceanic crust was recorded in the Maksyutov complex of the Uraltau Ridge, where Cambrian fauna was found among the reef body in the hyperbasite melange.