Pleistocene stratigraphy of the Vychegda River basin, European North-East

Abstract

The paper is devoted to the Middle and Upper Pleistocene stratigraphy of the Vychegda River basin, located in the far northeast of Europe, in the Timan–Pechora–Vychegda subzone of the Middle–Late Pleistocene glaciations. The available litho-/chrono-/biostratigraphy data were have been obtained from more than 20 natural outcrops along the valley of Vychegda and its tributaries, which were studied lithostratigraphically. Also radiocarbon, OSL, IR-OSL and 230Th/U dating was performed, together with pollen and palaeocarpological analyses. The oldest glacial deposits are related to the Pechora horizon (MIS 8), and the oldest numerically dated relate to the Rodionovo horizon (Schöningen, MIS 7), embracing the chronostratigraphic archive of the last ~250 ka. The Vychegda horizon (Drenthe + Warthe, MIS 6) includes surficial tills, glaciofluvial and glaciolacustrine sediments dated back to 186–111 ka. This ice sheet produced the ice-dammed lake which overflowed into the Kama-Volga and Caspian basin. The Last Interglacial–Glacial cycle is associated with the Sula horizon (Eemian + Lower Weichselian, MIS 5), and the Nenetsky superhorizon with the Laya (Middle Weichselian, MIS 4), Byzovaya (Middle Weichselian, MIS 3) and Polar (Upper Weichselian, MIS 2) horizons, reflecting alluvial and aeolian sedimentary environments. The chronostratigraphic record of the Byzovaya (67–27 ka) and Polar (27–1 1.7 ka) horizons is well supported with 14C, OSL, IR-OSL and 230Th/U-dates and biostratigraphic data. Unlike the predecessors' descriptions no glaciolacustrine deposits had been identified for these horizons. The Holocene floodplain, aeolian and peat bog deposits dated from 11.7 ka are widespread over the Vychegda catchment area.