Thickness distribution of quaternary deposits in the formerly glaciated part of the East European plain

摘要

A thickness map of Quaternary deposits in the south-eastern sector of the last Scandinavian Ice Sheet (SIS) and in areas of Middle Pleistocene Moscow (Warthe) and the Dniepr (Drente) stages of the Late Saalian glaciation on the East European Plain is presented (Main Map). The map of the thickness and related statistics of the Quaternary deposits were calculated from the difference between the current digital terrain model and the bedrock surface topography model. The distribution of Quaternary deposits shows that 29% of the mapped territory has sediments less than 25?m thick, 16% more than 100?m and 1.2% more than 200?m. Within the SIS area, the thickness of sediments in the southern sector exceeds threefold the sediment thickness in the eastern flank. This difference is attributed to the bedrock depression in the south-east of the Baltic Syneclise rather than to glacial dynamics. The calculated average thickness of the sediments within the SIS area is ca 50?m, in the formerly glaciated area outside the LGM it is ca 61?m and outside the glaciated area ca 14?m. Our study confirms that, in formerly glaciated areas, the spatial distribution of sediments did amplify the differences in glacial bed topography with the exception of the southern and eastern flanks of the Moscow glaciation area where exceptionally thick Quaternary deposits have inverted bedrock depressions into elevated areas in recent terrain. We suggest that the map presented improves existing knowledge of this area by adding detail and thus contributing to the on-going development of numerical ice-sheet models.