Rb–sr age of authigenic glauconite and u–pb age of detrital zircon from riphean and vendian deposits of the mezen syneclise, eastern european platform (keltmen–1 borehole)

The Rb–Sr age of gluconite and the U–Pb LA–ICP–MS age of detrital zircon from sandstones of the Riphean Okos Formation and the Vendian Ust-Pinega Formation were determined in the Keltmen-1 parametric borehole, drilled in the Vychegda trough of the Mezen syneclise in the European north of Russia. The model Rb–Sr age of glauconite (870–820 Ma) and the U–Pb age of the youngest detrital zircon (1005 ± 14 Ma) limit the time of accumulation of the Okos Formation to the first half of the Late Riphean, which is in good agreement with biostratigraphic data. The U–Pb age of the youngest detrital zircon obtained from the lower part of the Ust-Pinega Formation suggests that sedimentation of Late Vendian sandstones into the Mezen Basin began about 575 Ma. Thus, the duration of the stratigraphic break between the Riphean and Vendian is about 250–300 million years. In the Late Riphean and Late Vendian times, the Mezen basin was filled with terrigenous material of Archean–Late Proterozoic age (from 3.25 to 1.02 billion years), the sources of which were rocks of the Baltic Shield. In the lower part of the Ust-Pinega Formation, a population of detrital zircon of Vendian age (730–575 Ma) was discovered, a possible source of which could be rocks of the Proto-Ural-Timan Orogen.