Where was the outlet of the ice-dammed Lake Komi, Northern Russia?

Abstract

When ice-sheets on the continental shelves of the Barents and Kara seas expanded onto the Russian mainland, north-flowing rivers were blocked. The last proglacial lake in European Russia dammed between the ice-sheet in the north and the drainage divide in the south was Lake Komi, which has been dated to the Early Weichselian, 80–100 ka. The lake was about 1400 km long with a water level of about 100 m a.s.l. In the present paper, we discuss four alternative outlets: (1) Across the drainage divide towards the Volga River, leading the water southwards into the Caspian Sea; (2) across the Polar Urals towards West Siberia; (3) between the Barents Ice Sheet and the northern slope of the Kola Peninsula, leading the water northwestwards into the Norwegian Sea; and (4) across the drainage divide between the White Sea and the Baltic Sea catchment areas. Based on present knowledge, we consider the first three options unlikely. Across the divide to the Baltic Sea, a buried channel is mapped where the threshold altitude is lower than the Lake Komi level. We conclude that the outlet of Lake Komi probably followed this valley towards the Baltic Sea. However, the Scandinavian Ice Sheet overran this drainage divide during the Late Weichselian and therefore a younger till and other sediments cover the channel.