The Lower Precambrian in the Structure of Paleozoids of the Subpolar Urals

Resumo

Rocks of Early Precambrian age have been established in many polymetamorphic complexes of the Urals. However, there is no doubt that only two polymetamorphic complexes (Taratash and Aleksandrovsk), located on the western slope of the Urals, belong to the Archean–Paleoproterozoic sequence. They are surrounded by Lower Riphean weakly metamorphosed deposits. The reliable age data obtained for these deposits make it clear that the age of their metamorphism is Early Precambrian. Thus, there are different interpretations of the Early Precambrian dates obtained for other polymetamorphic complexes of the Urals (predominantly, Late Precambrian and Paleozoic ages). Therefore, their link with the Lower Precambrian sequence has been disputed by many researchers. Based on the results of mass U–Pb dating of metamorphic zircons from the gneisses of the Nyarta polymetamorphic complex of the Subpolar Urals and taking into account the age dates available, the Paleoproterozoic age of the earliest stage of metamorphism (2127 ± 31 Ma) was substantiated for the first time. This gives us grounds to say that the Nyarta complex, as well as the Taratash and Aleksandrovsk complexes of the Southern Urals, belong to the Lower Precambrian formations involved in the structure of the Uralides.