Provenance and U–Pb Age of Detrital Zircons from the Upper Proterozoic Deposits of the Polar Urals: To the Question of the Time of Formation of the Timan Passive Margin
The first results of U-Pb LA-SF-ICP-MS-dating of detrital zircons from terrigenous deposits of the Miniseishor suite of the Nyarovei series of the Harbei anticlinorium of the Polar Urals are presented. The series has a presumably Middle Riphean age and lies at the base of the section of the Polar Ural Upper Precambrian. The data obtained give grounds to limit the lower age interval for the formation of sediments of the Minisejshor suite abroad 660 million years ago. Allotment the Nyarovei series as a Middle Riphean straton is erroneous. Formation of the whole cut the Nyarovei series occurred in a relatively narrow age range at the end of the late Riphean. The dominant role in the formation of deposits of the entire series belonged to the products of erosion close arrays of deeply metamorphosed rocks.
U-Pb dating (LA-ICP-MS) of detrital zircons from the upper Cambrian - lower Ordovician terrigenous deposits of Baidarata allochthone (northern part of the Polar Urals) is performed. Analysis of the youngest populations of detrital zircons suggests wide development of Uralides instead of Preuralides as it was believed before. The source of sediments for investigated Baidarata allochtone rocks was probably Bedamel’ island arc rather than Timan orogen. According to results of statistical analysis of detrital zircons data from coeval deposits of Arctic region, similarity of sedimentary provenances for Baidarata allochtone, Novaya Zemlya and Severnaya Zemlya archipelagos is observed.
The paper describes two records of species of the genus Pseudobaeospora Singer emend. Bas. P. pillodii (Quel.) Wasser, collected in 2009 in the Teberda State Nature Reserve, was found before in Altai [reported as P. oligophylla (Singer) Singer, the type species of the genus], as well as in the Polar Urals. P. pyrifera is new to Russia. The descriptions are illustrated by line drawings and colour photographs.
Provenance Area and U-Pb Age of Detrital Zircons from the Upper Proterozoic Deposits of the Polar Urals