Late Pleistocene glacial and lake history of northwestern Russia

Abstract

Five regionally significant Weichselian glacial events, each separated by terrestrial and marine interstadial conditions, are described from northwestern Russia. The first glacial event took place in the Early Weichselian. An ice sheet centred in the Kara Sea area dammed up a large lake in the Pechora lowland. Water was discharged across a threshold on the Timan Ridge and via an ice‐free corridor between the Scandinavian Ice Sheet and the Kara Sea Ice Sheet to the west and north into the Barents Sea. The next glaciation occurred around 75–70 kyr BP after an interstadial episode that lasted c. 15 kyr. A local ice cap developed over the Timan Ridge at the transition to the Middle Weichselian. Shortly after deglaciation of the Timan ice cap, an ice sheet centred in the Barents Sea reached the area. The configuration of this ice sheet suggests that it was confluent with the Scandinavian Ice Sheet. Consequently, around 70–65 kyr BP a huge ice‐dammed lake formed in the White Sea basin (the ‘White Sea Lake’), only now the outlet across the Timan Ridge discharged water eastward into the Pechora area. The Barents Sea Ice Sheet likely suffered marine down‐draw that led to its rapid collapse. The White Sea Lake drained into the Barents Sea, and marine inundation and interstadial conditions followed between 65 and 55 kyr BP. The glaciation that followed was centred in the Kara Sea area around 55–45 kyr BP. Northward directed fluvial runoff in the Arkhangelsk region indicates that the Kara Sea Ice Sheet was independent of the Scandinavian Ice Sheet and that the Barents Sea remained ice free. This glaciation was succeeded by a c. 20‐kyr‐long ice‐free and periglacial period before the Scandinavian Ice Sheet invaded from the west, and joined with the Barents Sea Ice Sheet in the northernmost areas of northwestern Russia. The study area seems to be the only region that was invaded by all three ice sheets during the Weichselian. A general increase in ice‐sheet size and the westwards migrating ice‐sheet dominance with time was reversed in Middle Weichselian time to an easterly dominated ice‐sheet configuration. This sequence of events resulted in a complex lake history with spillways being re‐used and ice‐dammed lakes appearing at different places along the ice margins at different times.

The last Scandinavian Ice Sheet in northwestern Russia: ice flow patterns and decay dynamics

“…2). Glacigenic deposits comprising till, fluvial and lacustrine sediments of the Late Weichselian Scandinavian glaciation dominate subsurface exposures in the western part of the discussed region, whereas the areas to the east were glaciated by the Barents and the Kara ice sheets in Early and Middle Weichselian time Larsen et al 2006a). A comprehensive review of previous investigations in northwestern Russia has been provided by Demidov et al (2004).…”

Distribution of ice marginal moraines in NW Russia

“…From a geomorphological perspective, we note for example that moraines located outside the inferred Weichselian (Valdaian) limit (Larsen et al, 1999, p. 32;Svendsen et al, 2004, p. 56) appear to be more degraded by fluvial-and permafrost activity. Elsewhere, we note that revisions to the reconstructions of Larsen et al (1999), Larsen et al (2006) and might be needed, which is also supported by (Kalm, 2012, p. 23). Most notably in the Severnaya Dvina to Vologda area, our mapping suggests that the Last Glacial Maximum ice sheet extended about 150 km further east than previously thought (Lyså et al, 2011) (Figure 3).…”

The role of Arctic Ocean freshwater during the past 200 ky

“…23,000 km 3 ; [48]). Terrestrial fieldwork revealed a complex history of buildup and decay of the Eurasian ice masses during the last *200 ky (Svendsen et al [81]; Larsen et al [47]). Whenever these ice sheets decayed, pathways opened which allowed for the freshwater to enter the Arctic Ocean (Fig.…”