Loess/paleosol/cryogenic formation and structure near the northern limit of loess deposition, East European Plain, Russia

Quaternary loess/paleosol series and cryogenic phenomena within the East European Plain, Russia, are less studied near their northern limit than at their southern extents. The multi-disciplinary study of two loess/paleosol/cryogenic sections were carried out in the Moscow and Vladimir regions of Central European Russia, not far from the glacial limits of the Middle and Late Pleistocene. Generally, loess deposition within these regions has undergone syn- to post- deposition processes as evident from the laminated character, as well as post depositional soil moisture and temperature conditions that have commonly given rise to gleyzation and cryogenic deformations. The Middle Pleistocene Dnieper loess is calcareous here, but the Upper Pleistocene loess has been leached of carbonates. Both Upper and Middle Pleistocene paleosols have strong pedogenic features allowing their genesis to be determined whereas cryogenic deformations and other post-depositional features allow for the more detailed interpretation of cold epoch processes. Given these loess characteristics, the Moscow and Vladimir loess region may be considered as a specific facies of the East European loess area. The proposed Moscow–Vladimir loess region exhibits the complete sequence of stratigraphic units that are correlative with well known sequences along the southern part of the East European Plain. In the Moscow–Vladimir region, however, several horizons exhibit well developed cryogenic phenomena that indicate permafrost conditions and sufficient moistening during most of the cold epochs. Cryomorphic and hydromorphic processes have a strong influence on the composition and structure of loess formation. The Salyn paleosol of the Mikulino (Eemian) Interglacial time demonstrates strong clay illuviation as well as Kamenka and Inzhavino paleosols of the Middle Pleistocene age, both of which developed under boreal to sub-boreal climatic conditions. In contrast, the Bryansk and Romny interstadial paleosols have gleyic properties that suggest formation during incipient (discontinuous) permafrost conditions.