Scientific publications

Granitoids are widely represented in the Precambrian section of the Lyapinsky Meganticlinorium in the Subpolar Urals: over 20 relatively large massifs and numerous smaller bodies are distinguished. They have been more thoroughly studied than other areas of the northern Urals, but the issues of typification of these rocks remain unresolved. Until the 1990s, the subdivision and correlation of granitoids in this region were primarily based on the geological position of the granitoid massifs. Early Proterozoic, Late Riphean-Cambrian, and Late Paleozoic granitoid complexes were distinguished. With the acquisition of isotope geochronological data over the past 30 years, the main age interval for granitogenesis has been determined as 640–490 Ma BP. This has prompted many researchers to consider all Subpolar Ural granitoids as part of a single Late Riphean-Cambrian Salnero-Manhambo complex. This article substantiates the fallacy of this viewpoint. Based on an analysis of the geological position of granitoid massifs, the petrogeochemical characteristics and metamorphism of their constituent rocks, as well as the results of isotopic dating of granitoids, a long and complex process of granite formation in the Precambrian history of the Polar Ural lithospheric segment is reconstructed. It is shown that the crystallization of S-type granitoids associated with high-temperature metamorphic rocks is related to collisional processes during the formation of the Lower Proterozoic crystalline basement. In the Late Riphean, with rifting processes marking the beginning of the Protouralide-Timanide tectogenesis, there formed A-type granitoids of the Kozhimsky complex, and during the subduction stage in the Early Vendian, I-type granitoids of the Vodorazdelny complex with supra-subduction characteristics formed. The most extensive granite formation processes occurred in the Vendian and Early Cambrian, during the collisional and post-collisional stages of the Protouralide-Timanide development, which led to the formation of I- and A-type granitoids of the two-phase Salnero Manhambovsky complex.