Pleistocene loess-soil sequence and aeolian relief of Western Siberia: chronology and features of their formation

The article discusses the current state of chronostratigraphy and paleogeography of the loess-soil sequence of the Pleistocene of Western Siberia, which is one of the most complete in Northern Eurasia. It is shown that genetically loess is closely related to eolian formations formed as a result of activation of eolian processes in earlier arid epochs of the Late Cenozoic in North Asia. A deflationary and accumulative eolian relief, paragenetically associated with the formation of the subaerial formation, is described, showing a slight transfer of material that forms the loess stratum. It has been established that the eolian relief and the activation of eolian processes occurred during the cold periods of the Pleistocene with the predominance of southwestern winds. The basis of the stratigraphic subdivision and correlation of sections of the loess strata are fossil soils formed under strictly defined climatic conditions. Consistent tracking of the loess and soil horizons of the loess sequence of the Pleistocene of Western Siberia, taking into account radiocarbon and luminescent dating and the use of climatostratigraphic correlations, showed that its structure and composition clearly reflect the uniqueness of each paleogeographic epoch, associated with changes in the intensity of atmospheric circulation in the cold and warm epochs of the Pleistocene. The features of each specific epoch are recorded in a combination of unique individual features of certain horizons of the loess-soil sequence. In the alternating horizons of loesses and soils, a record of global and regional changes in landscapes and climate has been preserved, reflecting the originality and uniqueness of the paleogeography of each time epoch. The structure and composition of the loess strata reflect the different intensity of atmospheric circulation during the cold and warm epochs of the Pleistocene. It is shown that the chronological sequence of the loess-soil sequence of Western Siberia, based only on OSL dates, does not always coincide with the loess-soil sequence of Western Siberia, built on the integration of various approaches, with the predominant use of the paleopedological method, and therefore needs to be corrected. The best correlation results are achieved by combining all available dating methods with the involvement of biostratigraphic, sedimentological and geological data, based on the climatostratigraphic principle.