New data on granitoid ages from the Subpolar Urals in connection with the problem of distinguishing of the middle riphean granite-rhyolite Kozhim formation

The majority of researchers, basing on the data obtained on the age of granitoids of the Subpolar Urals, limit the processes of granite formation in this region to the interval of 490-650 million years. The actual materials presented in this paper, confirm the conclusion that processes of granite-genesis were most intensively manifested on the boundary of the Proterozoic and Paleozoic and testify to absence of the Late Paleozoic granitoid massifs in the Subpolar Urals. At the same time, the geological position of some granitoid massifs and ancient relic datings of the constituent rocks denote the reality of granitoid magmatism occurrence in the Late Preriphean and, in particular, in the Middle Riphean.