Soil-sedimentary sequences of lake depressions in the steppe zone of West Siberia (Russia)

Abstract

Lakes are widely distributed in the steppe zone of West Siberia (Russia). These lakes experienced climate-related fluctuations of water levels and corresponding rhythmic changes in the lake basin landscapes throughout the Holocene. Location, structure and properties of soil-sedimentary sequences (SSS) were studied near the Lake Bolyshoi Bagan, where four SSS profiles were examined. The profiles were located on the lake beach ridges and were of different age. Two types of sediments were found in the SSS structure, namely lacustrine sand of the shore facia (top and middle layers) and subaerial-deluvial loam with gleyic properties (lower layers). The studied SSS showed abrupt textural shifts between sandy deposits and loamy layers. The top part of the younger SSS also contains aeolian layers. The loamy layer, as compared with the sandy one, had increased contents of carbonates and dissolved salts. The lowest soil in all SSS was identified as Protosalic Relictigleyic Solonetz (Loamic, Columnic, Ochric). The surface and buried soils in all SSS were ascribed to the Reference Soil Group of Arenosols. Heterochronicity of surface soils is recorded in the different soil organic carbon content. The studied SSS reflect the interaction of environmental factors in the steppe zone of West Siberia during the Holocene: water level fluctuation in lakes, alternating aeolian and lacustrine sedimentation, and succession of pedogenesis and sediment accumulation periods.