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© 2020 Elsevier Ltd and INQUA Eurasian loess-paleosol sequences provide continuous records of global change in mid-latitude Northern Eurasia. The loess-paleosol sequence of West Siberia located in the central part of the mid-latitude Eurasian loess belt extending from West Europe to Yakutia is an outstanding paleoclimate archive in Northern Asia. The stratigraphy has been best documented on the left bank of the Ob River, in the so-called Ob Loess Plateau. This study focuses on the stratigraphy of the most complete Middle-Late Pleistocene loess-paleosol sequence at the Belovo section. The suggested high-resolution model of the Belovo Late Pleistocene stratigraphy is based on magnetic and sedimentological proxies and is correlated with other Eurasian loess records and with the global marine δ18O stratigraphy. The enviromagnetic signal at Belovo Loess-paleosol sequences shows a transitional pattern comparable with both typical Eurasian loess magnetic records. Detailed paleopedological interpretations of the magnetic and sedimentological data from the Belovo section have important implications for appropriate linking different Late Pleistocene climates and environments of other the well-known Eurasian loess provinces.

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.

We have analyzed the modern status of the chronostratigraphic differentiation of the loess–paleosoil series in southwestern Siberia and the results of luminescence dating of the reference section of the Altai low mountains near the settlement of Krasnogorskoe. A complete series of the Middle and the Late Pleistocene levels of paleosoil formation is distinguished. Six new dates were obtained for the section by optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL), and two samples were measured simultaneously, using quartz and feldspar, to control the light exposure and the reliability of the absolute age determined. The results obtained indicate the formation of the lower Berdsk paleosoil during the last interglacial period, which corresponds to Marine isotopic stage (MIS) 5e, and two dates of the underlying loess (127 and 149 ka BP) confirm that the age of this strata correlates with MIS 6. The age of the overlying Iskitimsk pedocomplex and of the horizon of Yeltsovsk loess is also substantiated by four OSL dates (48–39 and 39–25 ka BP). The final chronology confirms the previously elaborated chronostratigraphic scheme of the loess–paleosoil series in southwestern Siberia, which is based on a detailed morphological characteristic of paleosoils.

Analysing the genesis of Quaternary sediments is important for understanding the glaciation history and development of marine sediments in the northern part of Western Siberia. The problem is relevant since there is no consistent concept of the Quaternary sediment genesis in the north of Western Siberia. The formation of sediments is associated with marine, glacial and interglacial sedimentation conditions. The research objective is to identify the persistent features characterising the conditions of sedimentation and relief formation using the Nadym River basin as an example. The best method for studying this problem is a comprehensive analysis of the lithological, chronostratigraphic, petrographic and geomorphological studies of the Quaternary sediment upper strata. This study provides data from the analysis of the basic characteristics of quartz grains at the site. The rounding and morphology of the quartz grains provide evidence of possible glacial processing of some of the site strata. A petrographic study of selected boulder samples was performed. Some of them, by the shape and presence of striation, can be attributed to ice basins. The first use of a detailed digital elevation model applied to the study area made it possible to identify specific relief forms that could very likely be created during glaciations. Based on the analysis, we propose to consider the vast lake alluvial plains in the Nadym River basin as periglacial regions. This idea lays the lithological framework for understanding the reasons for the formation of the modern landscape structure. The materials and descriptions provided are of interest to researchers of Quaternary sediments, topography, vegetation and soil cover, particularly researchers engaged in revising the history of the natural environment development in the north of Western Siberia.

The loess-paleosol sequence of the Krasnogorskoye section in the low-altitude area of the northeastern Altai Mountains, can provide a yardstick for estimating the age of the Paleolithic sites and reconstructing environmental and climatic changes. Its correlation with the respective sequence of the southern part of the West Siberian Plain is evaluated. Five pedocomplexes are studied in detail, evidencing the evolution of the Middle and Late Pleistocene soil formation from the Shadrikha interglacial to the Karga interstadial. Buried soils of the Shadrikha, Shipunovo, Koinikha, and Kazantsevo warm stages formed under a climate that was warmer and more humid than today. After the Kazantsevo interglacial, both the range and the frequency of climatic oscillations show marked changes. It is demonstrated that the warm stages of this interval differ from the earlier ones by lesser warming and shorter duration by a cooler and more arid climate. Seven loess horizons dividing pedocomplexes are established. Nonmetric and metric analyses of quartz sand grains support the eolian origin of loess horizons under cryoarid conditions. The size of grains in the Late Pleistocene portion of the Krasnogorskoye section attests to the intensifi cation of the loess processes. Higher magnetic susceptibility during the cool stages and higher frequency-dependent susceptibility during the warm stages evidence marked climatic oscillations. After the Kazantsevo interglacial, the amplitude fades and the pattern of paleoclimatic signal recorded by the magnetic properties of loess and paleosol in the section are close to the “Alaskan” type.

Analysing the genesis of Quaternary sediments is important for understanding the glaciation history and development of marine sediments in the northern part of the Western Siberia. The key features of sedimentation and landform formation have been characterized for the first time in an example of a lithological column from the lower sources of the Nadym River. A comprehensive analysis was performed on the lithological, petrographic, and geomorphological data from the upper stratum of Quaternary sediments of the column. Based on the shape and morphology of quartz grains, some features of glacial processes for some layers of the studied sections were identified and analysed with special attention to the environmental history. A petrographic study of the boulder samples was carried out, which showed that the majority of samples are boulders of glacial origin according to their shape and texture. For the first time, digital terrain models were applied to study of the key plot where the lithological column is situated, which made it possible to identify the specific terrain areas that were most likely formed by glaciation. It is suggested that extensive lacustrine-alluvial plains existed in the Nadym River Basin, which was represented by postglacial sites. Such a concept provides a lithological basis for understanding the reasons for the formation of the present and recently formed environments and landforms. Therefore, it could be possible that local glaciation in the region of the Nadym River's lower course had an effect on the formation of the stratification of the layers of Quaternary origin.

The sedimentary record of aeolian deposits and geomorphic features of the aeolian landforms of Northern Eurasia contain important information that allows us to better understand the climate and environments of the Late Glacial and Early Holocene periods. At the same time, the degree of scientific knowledge about the timing of aeolian activity, as well as the landscapes that existed during these periods, differs significantly for different parts of this vast territory. Data on the sedimentological record and age estimations of aeolian phases are practically absent for the periglacial zone of Western Siberia, in contrast to that of Europe. This paper presents the first data on the Late Quaternary fluvio-aeolian environments of the southwestern part of Western Siberia, using two sections as examples. Our methods included field investigations, analysis of grain-size and chemical composition, quartz grain morphoscopy and infrared optically stimulated luminescence (IR-OSL) and AMS dating. The obtained results show that aeolian sands are common covering deposits within the study area. Two stages of aeolian activity were identified: the first during the Boreal period (9.2&ndash, 10.2 ka BP), and the second during the Atlantic period, beginning near 7 ka BP.