The Russian sector of the Eastern Arctic is characterized by large basins with thick sedimentary filling, primarily on the shelf and continental slope of the seas of the Arctic Ocean. A number of geological, geophysical, and geochemical features point to a hydrocarbon potential. At the same time, the age and composition of the sedimentary infill of the shelf basins have been controversial until now due to the lack of wells drilled in the shelf area. Six stratigraphic wells were drilled with core sampling in the eastern Laptev Sea (Anisin-Novosibirsk block owned by Rosneft) with a depth of 100 to 199.5 m during the Rosneft Stratigraphic Drilling in Arctic (RoSDAr) project in 2021. The results of complex biostratigraphic studies of the core show that the oldest strata in the well sections are Upper Barremian - Lower Aptian deformed silty mudstones (folded basement assemblage) overlain with angular unconformity by sands, silts, and clays of the Paleocene. The wells also penetrate the Eocene, Oligocene, and Miocene-Quaternary clastic rocks. A comprehensive analysis of stratigraphic drilling and seismic data refines the geological models of the region and provides better understanding of its hydrocarbon potential. The data show that Cenozoic strata play a more significant role in the sedimentary cover of the Laptev Sea than was previously assumed.

The results of the study of the Algai archeological site in the Lower Volga region (Aleksandrov-Gai district, Saratov oblast) are presented. The Algai settlement of the Neo-Eneolithic period includes several cultural layers formed over the last eight thousand years. Anthropogenically transformed light chestnut carbonate soils are the modern background surface soils (Eutric Cambisol (Loamic, Protocalcic, Ochric)). Soil, paleosol, and paleobotanical methods and radiocarbon dating have been used in this study. The soil stratum is represented by stratigraphically separated multitemporal full-profile Holocene soils showing different rates of eolian sedimentation and soil formation, vegetation change, and anthropogenic loads in the study area. Paleosol and paleobotanical data indicate hat the natural environment of the territory was not stable throughout the Holocene, and dry steppes existed in the studied territory. The most active sedimentation and soil formation occurred in the middle of the Holocene during the AT-2 period. During the stages of climate aridization, active sedimentation and vegetation suppression took place, which led to the disappearance of people from this territory. The stages of climate humidization were expressed in epigenetic soil formation with the development of organo-accumulative horizons under diverse plant associations and rich species composition of wild animals. These stages were favorable for human habitation. The obtained materials attest to considerable changes in the environmental conditions of the studied area in the Holocene marked by different stages of soil development and accompanied by periodic migration of humans. Unlike the background surface soil, buried soils were formed under extremely arid conditions and are characterized by soda salinization. This study made it possible to obtain new data on the climatic, soil, and paleobotanical features of the studied region.

The existence of vegetation of open environments with a predominance of grass–forb meadow associations and the participation of pine–oak forests was reconstructed on the basis of study of microphytofossils from the Lower Pleistocene deposits of the Taurida cave in central Crimea. These results are consistent with data on the composition of land vertebrates from the Taurida locality. The studied spectrum demonstrates similarity with the spore–pollen assemblage of the Berezan horizon of Ukraine with a maximum age of about 1.8 Ma. Based on the abundance of trichomes and plant fibers similar to those of Ficus carica Linnaeus, 1753 in the coprolites, it is assumed that the extinct hyenas Pachycrocuta brevirostris (Gervais, 1850) ate fig fruits in certain seasons.

The Stratigraphic Drilling Project of the Russian Arctic Shelf conducted by the PJSC Rosneft is aimed at discover the stratigraphic age and rock composition of sedimentary succession of its subsurface. In 2021, six shallow wells for the first time have been drilled with core sampling in the east of the Laptev Sea. Drilling revealed folded sedimentary succession dated back to the Late Barremian – Early Aptian. The synrift complex overlying unconformably dates to the Paleocene. The upper strata dates from Eocene to Pleistocene and contains significant hiatuses. The data discovered together with the results of seismic interpretation clarified the regional geological model and dated the stages of its tectonic evolution.

The Stratigraphic Drilling Project of the Russian Arctic Shelf, conducted by the Rosneft Oil Company, focuses their attention on the stratigraphic age and composition of rock complexes of the sedimentary basins. In 2021, six shallow boreholes for the first time were drilled with core sampling in the eastern part of the Laptev Sea. Drilling recovered sedimentary rocks of the folded basement that have been dated to the Late Barremian–Early Aptian. The synrift complex lying with angular unconformity has been dated to the Paleocene. The section of the overlying Eocene–Pleistocene sediments contains significant hiatuses. The data obtained by drilling together with the results of seismic interpretation allowed us to clarify the regional geological model and to date the stages of its tectonic evolution.

The results of the study obtained for spores and pollen from the subfossil spectra of samples from the Bykovsky Peninsula (northern Yakutia) are presented in order to compare them with the current vegetation composition, to consider the major cryogenic disturbances of palynological remains, and to analyze their cryogenic destruction processes. The abundant alien pollen of Betula sect. Nanae and Alnus in the spectra is due to open landscapes, relatively low pollen productivity, and the transition of herbs and shrubs prevailing in the local phytocenoses to a vegetative propagation in severe climatic conditions. The selective role of cryogenesis in the spore–pollen spectra formation is related to repeated sediment thawing and freezing cycles, resulting in physical damage (ruptures and cracks) in palynological remains. The results of research contribute to the study of the methodological aspects of palynotaphonomy in cryolithic zone sediments. They can be used to reconstruct the Neopleistocene landscapes and vegetation and to study cryopreservation of fossil living organisms and their diversity in the permafrost areas.

The paper presents the results of the study of Karginsky and Sartansky deposits of the Kolyma Lowland, synchronous with marine isotope stages (MIS) 3 and 2, and microphytofossils from them. During the accumulation of Karginsky deposits, various landscapes existed in this territory: communities of humid and dryish tundras, larch sparse forests, and tundra swamps, including habitats occupied by pioneer and steppe vegetation. The Sartansky deposits were formed under more uniform, cold and dry conditions. The results of the microbiomorphic study indicate the predominance of tundra herbaceous, mainly cereal associations in combination with the moss cover. Satisfactory preservation of microphytofossils from these strata is due to the specificity of the cryolithozone with a predominance of low temperatures throughout the year and low microbiological activity. The presence of spores and pollen with physical damage (ruptures and cracks) and corroded forms of phytoliths can be associated with their presence in the seasonally thawed layer during alternating freezing and thawing cycles.

The article presents the results of studying the spores and pollen preservation in soils of the permafrost zone in Yakutia (Kolyma Lowland, Bykovsky Peninsula, Yakutsk and its neighborhood). Data on the qualitative and quantitative composition of palynomorphs and on the patterns of their damage are discussed, and the mechanism of their cryogenic destruction is analyzed. Palynological residues with destruction of the chemical-biotic type (thinning of the walls, the formation of cavities as a result of the chemical action of microbes on them) are present singly or absent, which is probably due to the specificity of permafrost with a predominance of low temperatures throughout the year and a generally suppressed microbiological activity. Palynomorph damages of the physical type (ruptures and cracks) usually predominate. In samples from mineral horizons of loamy soils, the content of damaged palynological remains is 5–10%; in mineral horizons of sandy soil, it reaches 20%. In sandy soil, the content of unfrozen water films performing a cryoprotective role is low, and the palynomorphs are more susceptible to destruction by growing ice crystals during freezing. The large-size Gymnospermae pollen of Pinus and Larix is most susceptible to destruction. Damages are usually present on the dominant pollen of Poaceae and Betula sect. Nanae, as well as of Cyperaceae and Ericaceae. Few damage cases are characteristic of pollen grains of minor taxa: Salix, Duschekia, Asteraceae, Onagraceae, Ranunculaceae, Caryophyllaceae and of spores of Sphagnum and Bryales. There are no damages on pollen of herbs Valeriana, Polemonium, Artemisia, Chenopodiaceae, and Polygonaceae and on spores of Lycopodium, Diphasiastrum, Selaginella, and Polypodiaceae. The results can be used in the reconstruction of paleogeographic conditions for buried soils, as well as in the study of cryopreservation of biological objects in permafrost areas.

This paper presents results of the micropaleontological study of permafrost sediments exposed by CHUK 1/17 borehole at Cape Maly Chukochy, on the coast of the East Siberian Sea (Kolyma Lowland). Micropaleontological analysis, together with the lithological structure and the main physicochemical characteristics, enabled reconstructing sedimentation conditions during transition from nearshore marine to continental environments in the Middle and Late Neopleistocene. The existence of a tundra-steppe biome was confirmed for this region, which shows its significant advancement to the north. This study, using the example of this territory, shows the importance of studying microfossils for understanding the history of the region in the Quaternary and lays the basis for further microbiological and metagenomic studies of the sediments exposed by the borehole.

The Eurasian (née European) Modern Pollen Database (EMPD) was established in 2013 to provide a public database of high-quality modern pollen surface samples to help support studies of past climate, land cover, and land use using fossil pollen. The EMPD is part of, and complementary to, the European Pollen Database (EPD) which contains data on fossil pollen found in Late Quaternary sedimentary archives throughout the Eurasian region. The EPD is in turn part of the rapidly growing Neotoma database, which is now the primary home for global palaeoecological data. This paper describes version 2 of the EMPD in which the number of samples held in the database has been increased by 60 % from 4826 to 8134. Much of the improvement in data coverage has come from northern Asia, and the database has consequently been renamed the Eurasian Modern Pollen Database to reflect this geographical enlargement. The EMPD can be viewed online using a dedicated map-based viewer at https://empd2.github.io and downloaded in a variety of file formats at https://doi.pangaea.de/10.1594/PANGAEA.909130 (Chevalier et al., 2019).

This work presents the results of the study of microbiomorphs (pollen, spores, phytoliths, diatoms, shells of testate amoebae, sponge spicules, plant tissue remains) from the paleosols of the Upper Quaternary deposits of the Kolyma Lowland. The analysis of their abundance and diversity, as well as the relationships between different types of biomorphs, made it possible to clarify the genesis of the paleosols and the nature of the vegetation cover.

The results of the study of the structure of buried soils of Marine Isotope Stage (MIS) 3 on the Kolyma Lowland and of the analysis of microphytofossils from these soils are given. The data of the spore-pollen and phytolith analyses confirm the similarity of the natural conditions for the formation of buried soils and the tundra aspect of reconstructed landscapes under a progressive decrease in heat and moisture supply during MIS 3.

The results of interdisciplinary research conducted at the Eneolithic archeological site Oroshaemoe (5–7 ka BC) in Saratov oblast are presented. The studied soils are calcareous light chestnut soils (Eutric Cambisols (Loamic, Protocalcic, Ochric)); in the archeological excavation, they are human-modified and contain various artifacts. A set of pedological, paleopedological, paleoclimatic, and paleobotanical methods and radiocarbon dating have been applied. Information on alternation of the periods of humidization and aridization of the territory, stages of soil formation and sedimentation, and on the vegetation cover in the Holocene at the archeological site has been obtained and refined. According to our data, periodic alternation of more humid and more arid conditions has taken place since 7245 ± 60 BP. The stages of aridization were accompanied by the short-term sedimentation related to the activation of eolian processes. Loesslike sediments deposited during these stages are archeologically sterile (do not contain artifacts) and are relatively thin in comparison with the cultural layers separating them. The stages of humidization were marked by more active sedimentation accompanied by soil formation. The obtained data suggest that the past 5000 years have been the period of some humidization of climatic conditions. Preliminary estimates of sedimentation and soil formation rates in the Holocene in the study area attest to their considerable fluctuations. Thus, the rate of soil formation varied from 35 to 0.8 cm per century. The results of this study allow us to refine paleoclimatic reconstructions for the considered area. Periodic changes in the environmental conditions during the Holocene affected the life of the tribes, patterns of human settling, and regional and, possibly, global migration processes. The reconstruction of natural and climatic features of the archeological site and its comparison with published data attest to the uneven paleogeographic situation in the Lower Volga region. It is argued that the chronology of landscape and climatic changes during the Holocene as presented in the publications for the southern arid regions of the East European Plain needs to be revised and made more detailed.

The results of investigation of the phytofossil complexes (spore-and-pollen spectra, phytoliths and seeds) from surface samples characterizing diff erent plant associations from the area of the Kolyma lower course are presented. The peculiarities of fossilization of vegetative micro remnants in various ecotopes of the permafrost zone have been revealed. The formation regularities of the examined complexes and the possibility of combined application of palynological, phytolith and carpological methods for paleoecological reconstructions of the Upper Quaternary deposits in the region have been defi ned.

Spore–pollen spectra of surface samples characterizing different plant associations in the Lower Kolyma River basin are studied. The formation features of the studied spore–pollen spectra are determined, as well as their potential for past vegetation reconstruction, paleogeographic constructions, and stratigraphic correlation of Quaternary deposits in Northeastern Russia.

A detailed study of the Duvanny Yar section in the Kolyma Lowland (Yakutia) provides the most extensive knowledge to date about late-Pleistocene soil formation processes and environments in the North East Siberian Arctic. Late-Quaternary palaeoenvironmental changes were reconstructed using paleopedological data and a range of palaeoecological bio-indicators (palynomorphs, plant macrofossils and insects). The frozen sediments representing marine isotope stage 3 (MIS-3), which encompasses the Karginsky interstadial, include profiles of four palaeosols of different ages. The oldest palaeosol is early Karginskian, and three overlying soil horizons represent a late-Karginskian pedocomplex. Palaeopedological data indicate a change of from synlithogenic soil formation processes to epigenic ones during these intervals. The intervening periods of synlithogenic pedogenesis were accompanied by active accumulation of eolian deposits. The Earlier Karginskian period of pedogenesis occurred in the absence of eolian sedimentation and when summer conditions were warm. The wide spectrum of peaty and peaty-gley soils observed in the late-Karginskian deposits developed under conditions of progressive cooling. The structure and content of fossil rodent burrows dated to approximately 30 000 yr BP from frozen late-Pleistocene deposits at Duvanny Yar indicate an arid and severe climate, a depth of active layer of 60-80 cm, and a wide distribution of disturbed habitats with pioneer and steppe vegetation. (C) 2011 Elsevier Ltd. All rights reserved.