Mikuhno and Valdai palaeoenvironments in the Vologda area, NW Russia

Nine representative sediment sequences and pollen diagrams obtained during the Quaternary mapping programme carried out by the Geological Expedition (St. Petersburg, Russia) between 1960s and 1980s are presented from the Vologda area, NW Russian Plain, covering the time span from the Moscow cold (Saale) stage into the Late Valdai (Weichsel) substage. This work was done in order to shed light on the evolution of palaeoenvironments, vegetation and climate in the area. The results suggest that two major depressions in the Vologda area, namely the Mologa-Sheksnian and Prisukhonian basins, witnessed lake level fluctuations that were most likely closely linked to climatic fluctuations. It is suggested that during the Mikulino (Eem) thermal optimum most of the lowland areas were dry land. However, during the Early and Middle Valdai, the large depressions started to flood as a result of wet and cold climate. This caused the accumulation of lacustrine and also lacustrine-alluvial and lacustrine-bog sediments into the basins. The Valdai forest composition varied between closed spruce-birch forests and treeless tundra. Lakes persisted throughout the Valdai stage including the extremely dry last glacial maximum (LGM)-time when the Scandinavian Ice Sheet dammed the northbound rivers in the Vologda area. (C) 2001 Elsevier Science B.V. All rights reserved.