ИСТИНА

The results of a multimember chronostratigraphic subdivision of the loess-paleosoil formation (LPF) of the East European Plain are elucidated. A correlation of basic paleogeographical events of the loess areas in the Pleistocene has been assessed. It has been established that the period of the LPF development on the East European Plain comprises 17 paleogeographic stages (9 interglacials and 8 glacials between them) - Petropavlovka interglacial (Interglacial I, Waardenburg), Pokrovka cooling (Glacial A), Gremyach’e interglacial (Early Il’inka, Interglacial II, Westerhoven), Devitsa cooling (Inter Il’inka, Glacial B, Unstrutian), Semiluki interglacial (Late Il’inka, Interglacial III, Rosmalen), Don glacial (Glacial C, Helmian), Muchkap interglacial (Interglacial IV, Noordbergum), Oka glacial (Elsterian), Likhvin s.str. interglacial (Holsteinian), Kaluga glacial (Borisoglebsk glacial), Chekalin interglacial (Kamenka, Domnitz), Zhizdra cooling (Orchik cooling), Cherepet‘ interglacial (Romny interglacial), Dnieper glacial (Saalian), Mikulino interglacial (Eemian), Valdai glacial (Weichselian) and the continuing Holocene interglacial. Smaller climate-stratigraphic units are identified within the glacials and interglacials: those are endothermal coolings (cold spells), thermoxerotic and thermohygrotic stages and substages of interglacial climatic rhythms; stadials, interstadials, interphasials, cryohygrotic and cryoxerotic stages and substages of glacial climatic rhythms. Endothermal coolings have been identified in a majority of interglacials. Environment and vegetation evolution of the epochs of the loess and soil formations in the East-European loess province has been characterised by pollen data of the reference sections of the Upper Oka (Likhvin-Chekalin section), the Upper Don (Strelitsa section), the Middle Kuma (Otkaznoe section), the Middle Dniester (Molodova section, Ketrosy section) and the Middle Desna (Arapovichi section) regions of the East European Plain. The reconstructions indicate a wide expansion of periglacial tundras and forest-tundras in the central regions of the East European Plain, and dominance of periglacial steppes and forest-steppes (more rarely - tundra-forest-steppes) in the south; they also suggest a considerable complexity of succession processes in phytocoenoses evolution. Ice sheets probably covered the north of the East European Plain at all the cold stages, and occasionally penetrated the central regions of the plain. Several cold stages in the LPF development which cannot be reliably correlated with till horizons on the East European Plain resembled closely the Don (=Helmian, Glacial C), Dnieper (=Saalian) and Valdai (=Weichselian) glaciations in the scale of climatic changes and ecosystem transformations. As is evident from the pollen data, fossil soils of the Central glacial-periglacial loess regions (Likhvin section in the upper Oka region and Strelitsa section in the upper Don region) developed in interglacial and interstadial climate; some of the soils were formed under stenoperiglacial conditions corresponding to glacial stages of glacial epochs. Loess horizons in these regions were formed in the glacial climate only. Whereas in the south of the East European LPF province (Molodova, Kishlyanski Yar and Ketrosy sections in the middle Dniester region, Arapovichi section in the middle Desna region, and Otkaznoe section in the middle Kuma region, and others), the loess horizons were formed during all the stages of glacials, including interstadials and interphasial warmings, as well as during thermoxerotic stages and endothermal coolings of interglacials. Paleosoils developed there at all stages of interglacials, and also during interstadial and interphasial warmings and cryohygrotic stages of the glacials.