Loess-paleosol record of MIS 3-MIS 2 of north-east Cis-Salair plain, south of West Siberia

We present results for three sections with a representative loess record of the end of the Late Pleistocene from the south-east of Western Siberia. These sections are characterized by different structure and formed in different geomorphological position of Ob Loess Plateau and Cis-Salair plain. The age of deposits within MIS 1 MIS 3 is determined by radiocarbon and OSL dating. Data on the quartz grain morphology confirmed that aeolian processes were the main factor in the accumulation of studied profiles, the influence of cryogenic weathering was also noted. Evidence of the MIS 2 warmings have been recorded in the northwestern Salair region (Ust'-Chem section), presented by two weakly developed Late Glacial paleosols formed 14.9-12.3 kyr ago. The distribution of magnetic susceptibility and grain size records in the Lozhok and Klyuchi sections reveals a period of relatively long term aridization with an increase in atmosphere dustiness in the lower part of the Eltsovka loess (MIS 2). The trend of increase in humidity with decrease in the atmosphere dynamics is observed during the second part of MIS 2. An event of activation of local aeolian processes with dune formation took place 47 kyr ago (the first half of the Karga interstadial; MIS 3) in the Klyuchi section. It is supposed that the geomorphological situation and the presence of nearby material available for local redeposition was a significant agent in the formation of the lower layer of Klyuchi and Ust-Chem sections. It was formed by combined deposition of silt material from the atmosphere flow and by the local aeolian transportation of sand. Permafrost-solifluction event was established in the northeastern part of the Ob Loess Plateau at about 23 ka.

Automated summary

This study examines the loess records of the Late Pleistocene in Western Siberia, analyzing different sections to understand the geomorphological structure and climate changes. The results show that aeolian processes were the main factor in the accumulation of loess in these sections, with some influence from cryogenic weathering. The study also identifies periods of short-term warming and long-term aridization during the Late Glacial period. Additionally, evidence of local aeolian processes and dune formation was observed in certain sections.