ПЕРВЫЕ РЕЗУЛЬТАТЫ ЛЮМИНЕСЦЕНТНОГО ДАТИРОВАНИЯ ЛЁССОВО-ПОЧВЕННЫХ СЕРИЙ ЮГА ЗАПАДНОЙ СИБИРИ (ОПОРНЫЙ РАЗРЕЗ ЛОЖОК)

The article presents the first results on luminescence dating of the Upper Pleistocene deposits of the loess-soil series in Western Siberia. In the key section Lozhok, eight horizons were identified, reflecting the main stages of the development of the environment of the region, including three paleosols, previously correlated in the chronostratigraphic scheme of Western Siberia with the stages of warming MIS 3 and MIS 5. The chronology was obtained from 15 new optically stimulated luminescence (OSL) dates. The dating was carried out according to a modern technique with the analysis of the accumulated dose and age using three signals (OSL, IRSL₅₀, pIRIR₂₉₀). The high convergence of the results of measurements according to the pIRIR₂₉₀/Q and IR₅₀/Q protocols indicates a sufficient bleaching of the feldspar and quartz grains. In accordance with the standards accepted in luminescent dating, the obtained series of dates is reliable, and then the resulting chronology is considered as reliable. Based on the dating results, the age of formation of all stratigraphic horizons was determined. Analysis of the loess-soil sequence of the Upper Pleistocene, based on the luminescence chronology of the Lozhok section, showed a discrepancy with the loess-soil sequence developed based on a detailed study and tracing of horizons of buried soils and loesses in the most complete subaerial sections of Western Siberia. In the section, the presence of an erosion boundary is highlighted; the duration of the hiatus in sedimentation was about 95 thousand years. The upper pedocomplex is characterized by an age of 123 ± 11 thousand years and corresponds to MIS 5, and the lower one is 196-216 thousand years old and correlates with MIS 7. Analysis of sedimentation conditions indicates a sharp increase in the rates of loess accumulation in MIS 2, and the difference in the content radionuclides ²²⁶Ra, ²³²Th, and ⁴⁰K reflect a change in the source of the material and a possible rearrangement of the regional wind rose. The authors believe that the results obtained at this stage are controversial and require additional research.