Evolution of a proglacial lake in the Izborsko‐Malskaya Valley, Russia, in the Late Glacial

Abstract

A proglacial lake system formed during the Late Valdai (Weichselian) Ice Sheet recession on the East European Plain. Poor knowledge about chronology, levels and the drainage pathways of ice-dammed lakes does not allow us to fully evaluate their palaeogeographic significance. This study focuses on the Izborsko-Malskaya Valley where fingerprints of a glaciolacustrine environment were found. Based on litho-, biostratigraphic and geochronological data, it is estimated that the proglacial lake in the Izborsko-Malskaya Valley existed from ~14.3 ka cal. BP (the Vashinogorskaya Valley from ~14.9 ka (optically stimulated luminescence)) to 13.2 ka cal. BP. The maximum level was ~72 m a.s.l. (above sea level) and the minimum was ~53 m a.s.l. Sedimentation proceeded mostly in deepwater conditions. The ice-dammed lake in the Izborsko-Malskaya and nearest valleys could have been part of a huge lake on the Pskov lowland which formed after ~15.7 ka cal. BP. The lake level dropped rapidly when the proglacial Lake Pskovsko-Chudskoe (Peipsi) connected with the Baltic Ice Lake. A lacustrine regime was preserved only in the southern portion of the Izborsko-Malskaya Valley after drainage and still exists in the modern lakes. The presented approaches to the ice-dammed lake reconstruction could be useful for the verification of other lakes which existed on the East European Plain.