U-Pb dating of detrital zircons from basal Post Paleoproterozoic metasediments in the Subpolar and Polar Urals: evidence for a Cryogenian, not Mesoproterozoic age

In the last ten years, U-Pb ages of detrital zircons has been obtained from Precambrian metasediments of some regions of Timan and the northern part of the Urals, which lie at the base of the visible Post Paleoproterozoic section of the Timan-Ural region. However, the basal status of these stratons remains unproven due to the lack of their relationship with the underlying formations. This article presents the first U-Pb-dating of detrital zircons from terrigenous metasediments of the Puyva suite (Subpolar Urals) and the Miniseyshor suite (Polar Urals) which reliably represents the basis of the Mesoneoproterozoic of the Timan-Northern Urals. The maximum age of deposition (MAD) detrital zircon the onset of sediment deposition is about 870 Ma for the Puyva suite and 660 Ma for the Nyarovey series, which corresponds to the Cryogenian. Therefore, the widespread opinion that the Puyva suite and the Nyrovey series are Mesoproterozoic in age is incorrect. Theis geochronological information integrated with MADs from other Precambrian complexes of the Timan- Urals region, suggests that the Timanian passive continental margin probably formed Tonian-Cryogenian.