Loess and its derivatives in a common sedimentary and geomorphic evolution of the East European Plain

Abstract

This paper discussed the loesses of the East European loess province and their geological context through the prism of a rich research heritage and new data on their primary litho-facial features, distribution, sedimentary architecture and specific landforms. This allows determining Loess Formation including facies of proper aeolian loess and loess-derivatives: loess-like slopewash and loess-like balka alluvium. The permanent factor of loess deposition is considered to be the fallout of globally transported dust. It lasted from the Early Pleistocene to the Holocene inclusive. It was slow and uniform, with some periods of high (Last Glacial) and slackened (interglacial epochs) rates. Wind scouring of bare loose deposits in river valley bottoms and coastal bluffs as well as glacial deposits provided neighbor loess deposition during short spans at the end of the Middle and Late Pleistocene continental glaciations. Loess-derivative slopewash and balka alluvium deposited during periods of heavy rainfall or intense snow melting as a result of sheet erosion. Both main processes resulted in: aggradation of the East European Plain; burial or smoothing of previous negative landforms and creation of new positive ones (loess “waves”, ridges, long gentle slopes, slopewash fans and aprons). The aggradation as well as physical and mechanical properties of loess favored sagging with origin of local depressions, intensified rill-gully and balka erosion and coastal abrasion. During the consideration of loess-paleosol stratigraphy, doubts are expressed about the correctness of long-range correlations of the loess derivatives sequences or loess belonging to riverside areas due to different depositional dynamics.