The results of a ground-penetrating radar survey and multiproxy studies of the sediment cores collected from two lakes in the Valdai Highlands (East European Plain) provide new insights into the late glacial and Holocene environmental history of the region situated in the marginal zone of the last Scandinavian ice sheet. The cores were analyzed for organic carbon and nitrogen content, as well as for pollen and diatoms. The chronology of the cores is based on radiocarbon dates and pollen-based stratigraphy. The studied records document that vast dead ice masses and associated ice-dammed lakes existed in the Valdai Highlands area until similar to 14 cal ka BP. Open tundra-steppe communities dominated the study area during the Oldest Dryas, B & oslash;lling, and Older Dryas (between ca. 17 and 14 cal ka BP), but dwarf birch (Betula nana), shrub alder (Alnus fruticosa), and willow (Salix) were also common. Scots pine forest (Pinus sylvestris) became common for a short interval during the B & oslash;lling warming (ca. 14.9 and 14.4 cal ka BP). The appearance of spruce (Picea) forest in the landscape occurred in the beginning of the Aller & oslash;d warming (similar to 14 cal ka BP), but the open steppe-like plant communities remained common until the onset of the Holocene. The modern lake systems emerged at similar to 10 cal ka BP, marked by an onset of organic-type sedimentation and the appearance of modern-type forests. The Mid-Holocene (similar to 8-4 cal ka BP) was the warmest time, as documented by the maximal distribution of temperate and broadleaved taxa in the region. The onset of agricultural land use and simultaneous trend of increasing lake trophic state and increasing paludification in the area is recorded at similar to 2.5 cal ka BP.

Across the northern East-European Plain, and especially in the Mologa-Sheksna Lowland (MSL), short-term climate variability in the Late Glacial caused significant palaeohydrological alterations, which drove vegetation successions. The MSL is prominent for the dense river and lake network, which have evolved through multiple water level and sedimentation regime oscillations since the Last Glacial Maximum. Extensive bogs inherit morphology of the basins, which had been filled with paleolakes for several millennia until their ultimate drainage in the early Holocene. Correspondingly, intricate morphology of lakes and deltas conditioned mosaic distribution of vegetation across the MSL. Continuous palaeoenvironmental record for the Holocene in the MSL has been derived from several peat and lacustrine sites. The data regarding the Late Glacial is much more scarce, due to the low abundance of the relevant deposits, and poor state of preservation. Except for the MSL bog plains, pronounced evidence for the short-term palaeoenvironmental offset was discovered in the section of the sand terraces in the Mologa River catchment. The onset of Allerød warming has been traced via an organomineral layer, which was confirmed to have a continuous bedding over the area of 100 km2 in the central MSL, as revealed by auger drilling and ground-penetrating radar survey at eight sites. This layer dates back to 13.4– 12.1 cal ka BP, and is represented by interbedding of fine sand with medium decomposed peat. Palynological and plant macrofossil studies of the buried peat from three boreholes reveal several inferences about the formation of this layer and the general palaeohydrology of the MSL in the Late Glacial. The first palaeoclimatic evidence is provided by the high abundance of spruce pollen and bark pieces, supporting the hypothesis that the layer formation occurred during the Allerød interstadial, which was characterized by a rapid expansion of spruce in the region. Secondly, high abundances of pollen and remains of hydrophytes or hydrophilous lacustrine vascular plants (Cyperaceae, Poaceae, Potamogetonaceae), mosses (Sphagnum sp., Drepanocladus aduncus and Calliergonella cuspidatum) and chara algae indicate lentic shallow water environment or the proximity of the paleolake shoreline. In general, a transition from shallow lacustrine environments, surrounded by spruce-birch forests, to tundra steppes and bogged grasslands can be deduced, based on the pollen spectra and subfossils assemblages. Third, true altitude of the buried peat layer (96.5 – 102.5 m above sea level) may be considered as a limit for the paleolake water level in the Allerød, because it delineates the surface uncovered from water or proximate to the shoreline. Thus, its lowermost discovered position can trace the extent to which the paleolake level had dropped in the Allerød. The peat was rapidly formed and buried during the late Allerød, which makes it a reliable regional isochronous stratigraphic level for the poorly studied Late Glacial sedimentary successions. This level can be used as a reference point for tracing recent short-term climate-environment interactions and effects.

With its numerous environmental archives stored in lake and peat sediments and relatively low human pressure, the Lake Onega region in eastern Fennoscandia is regarded as a particularly promising area for studying past changes in vegetation and climate since the Lateglacial period. The 885-cm-long sediment core RZ19 (62°27′53″N, 34°26′4″E) was collected from Razlomnoe Peat on the northern shore of Lake Onega in 2019, radiocarbon-dated and analysed for pollen and cryptogam spores. The age-depth model suggests continuous sedimentation since ca. 11,800 a BP (all ages given in years (a) or kiloyears (ka) before present (BP) with BP referring to 1950 CE). The results of pollen analysis and pollen-based biome reconstruction show rapid afforestation of the area in the Early Holocene, although the scores of the tundra biome remain relatively high prior to ca. 11,450 a BP, suggesting that the vegetation was likely more open than today. Between 8300 and 8000 a BP, Betula sect. Albae shows a marked increase in pollen percentage, while Pinus sylvestris experiences a marked decrease. These changes coinciding with the 8.2 ka BP cooling event indicate less favourable conditions for Scots pine while being beneficial for fast-growing birch. The transition from the Early to Middle Holocene (i.e. from Greenlandian to Northgrippian) is marked by an increase in pollen productivity, spread of Picea and further afforestation of the area. The decrease in arboreal and Picea pollen percentages and the abrupt increase in landscape openness after ca. 4000 a BP mark the onset of the Late Holocene (i.e. Northgrippian-Meghalayan transition) and likely reflect the combined effect of insolation-induced temperature decrease and associated paludification and forest retreat rather than a decrease in atmospheric precipitation and/or spread of Late Neolithic agriculture.

The bottom sediments of the Russian Arctic seas have been studied to varying degrees. The least attention has been paid to the East Siberian Sea, the Quaternary geology of which remains largely overlooked. This article summarizes the results of a comprehensive research on the East Siberian Sea, including the first paleomagnetic analysis of nine sediment cores collected during three cruise expeditions as part of the program “State Geological Mapping of the Territory and Continental Shelf of the Russian Federation at the Scale of 1:1 000 000”. The results obtained show that the processes and conditions of sedimentation vary in different parts of the East Siberian Sea.

—The rarely visited islands of the Kara Sea in its Pritaymyr zone have been studied during a geological survey on the scale 1:1,000,000. The Quaternary deposits of the islands are represented by the Middle Neopleistocene to Holocene marine, lacustrine-marsh, alluvial and slope sediments. New radiocarbon and uranium-thorium dating has been obtained for the Quaternary sediments, using organic remains (wood, peat, mollusk shells). For the first time, dating on sandy sediments was obtained for the islands, using the method of infrared optically stimulated luminescence (IR-OSL). The sediments of marine terraces are of the greatest distribution on the islands; these sediments can be correlated with the Karginsky (MIS 3) horizon, lacustrine-marsh sediments and deposits of the cover complex, containing flora remains, mainly the Holocene.

A radiocarbon-dated sediment core collected from the small freshwater Lake Kamenistoe, in the central part of the Kola Peninsula, provides a pollen record of vegetation and climate history of this part of Fennoscandia and the European Arctic during the past ca. 13,000 years. In contrast to existing Scandinavian Ice Sheet reconstructions, the record shows that the study site was ice-free at 13 cal. kyr BP, thus allows to improve our knowledge on deglaciation dynamics in North Europe. The biome reconstruction results together with other pollen records from the wider region suggest that forest-tundra surrounded Kamenistoe at the end of the BullingAllerud interstadial and that the reconstructed presence of trees is not determined by far-distance pollen transport. The spread of pine in the study region started ca. 9.3 cal. kyr BP, and maximum pollen percentages during 8.2-4.2 cal. kyr BP mark the Holocene thermal optimum. Progressive climate cooling accompanied by increasing moisture levels from 6 cal. kyr BP is indicated by the spread of spruce (boreal evergreen conifer), reflecting the expansion of taiga forests. In contrast to some previous interpretations, we argue that the spread of pine in the Early Holocene and spruce in the Middle Holocene did not follow zonal expansions, but rather originated from scattered small populations withing the study region. Archaeological records from northern Fennoscandia suggest that postglacial human occupation on the Kola Peninsula began no later than 10,000 years ago. This northward expansion of hunter-gatherers was likely related to the continuous Early Holocene warming, which not only resulted in less harsh climatic conditions for human occupation, but may have also pushed reindeer populations to the study region. This game animal, which has been a major resource for humans, prefers July temperatures below 12-13 degrees C and thus may have migrated to cooler environments during the Early Holocene.

The numerous lake and peat sedimentary archives of Central European Russia are ideal for studying the Lateglacial-Holocene climate and vegetation history of the region. However, robustly dated palaeoenvironmental records have only become available in the last decade and are still few and far between. Together with the continuously growing archaeological record and increasing focus on absolute dating of cultural assemblages, such records, where available, offer an excellent opportunity to study human-environment interactions in the region. For this study we selected one of the most detailed regional pollen records, from a 4.5-m-long sediment section from Zmeinoe Mire (56 degrees 16 ' 53 '' N, 31 degrees 15 ' 36 '' E) at Zhizhitskoye Lake (165 m a.s.l.). We performed quantitative pollen-based biome reconstruction and constructed a Bayesian age-depth model to ensure maximum chronological control of the sediment succession. To link the reconstructed vegetation changes to human activities, we gathered and summarized available archaeological data from the study area. Our results show that humid conditions and taiga-like patchy forests (spruce, pine, birch) dominated the study region during the Lateglacial. The Early Holocene (ca. 11,650-8000 cal yr BP) was marked by a warming and drying trend indicated by the spread of cool-temperate summergreen broad-leaved trees and shrubs (elm, lime, hazel) and the retreat of spruce. Warmest conditions, expressed by the maximum contribution of temperate deciduous woody taxa to the pollen assemblages, were recorded during the Middle Holocene (ca. 8000-4000 cal yr BP) when Mesolithic and Neolithic hunter-fisher-gatherer groups flourished in the region. The pollen record suggests that the regional climate became cooler and wetter after 4000 cal yr BP, which may explain the decline of the Neolithic pile dwelling settlement Naumovo at Zhizhitskoye Lake around 3800 cal yr BP. Evidence for human impact on natural forest vegetation becomes visible from 5000 cal yr BP, although it remains at modest levels until the end of the Neolithic (3500-3000 cal yr BP). Decline in arboreal pollen percentages intensified after ca. 2800 cal yr BP, indicating the onset of increased deforestation for pasture, farmland, construction material and fuel by Iron Age populations. This is in line with the foundation of the fortified Iron Age Anashkino settlement north of Zhizhitskoye Lake dated to around 2750 cal yr BP. Forest clearance further increased during the second half of the Iron Age (5th century BCE-5th century CE) and again from ca. 1200 cal yr BP after the onset of the Middle Ages.

ABSTRACTHydro‐acoustic and seismic data and 2‐ to 16‐m‐long sediment cores from the central area of Lake Taymyr (Taymyr Peninsula, central Russian Arctic) were investigated to reconstruct its sedimentation history. Granulometric, chronological, geochemical and biological data from the sediment cores reveal two lowstands and two highstands of the lake level, which is today located ca. 5 m above sea level during summer. Our study confirms the presence of an ice sheet blocking the drainage of Lake Taymyr during the latest Weichselian. Although chronological control of the sediment cores does not allow us to unambiguously constrain the time frame for each of the lake stages, the proposed timing of events is in good agreement with regional terrestrial archives as well as marine signals on the Kara Sea Shelf. Overall, the data show that the evolution of Lake Taymyr involved a complex interplay of regional climatic, glacial and sea‐level changes.

Bolshaya Imandra, the northern sub‐basin of Lake Imandra, was investigated by a hydro‐acoustic survey followed by sediment coring down to the acoustic basement. The sediment record was analysed by a combined physical, biogeochemical, sedimentological, granulometrical and micropalaeontological approach to reconstruct the regional climatic and environmental history. Chronological control was obtained by 14 C dating, 137 Cs, and Hg markers as well as pollen stratigraphy and revealed that the sediment succession offers the first continuous record spanning the Lateglacial and Holocene for this lake. Following the deglaciation prior to c . 13 200 cal. a BP , the lake's sub‐basin initially was occupied by a glacifluvial river system, before a proglacial lake with glaciolacustrine sedimentation established. Rather mild climate, a sparse vegetation cover and successive retreat of the Scandinavian Ice Sheet ( SIS ) from the lake catchment characterized the Bølling/Allerød interstadial, lasting until 12 710 cal. a BP . During the subsequent Younger Dryas chronozone, until 11 550 cal. a BP , climate cooling led to a decrease in vegetation cover and a re‐advance of the SIS . The SIS disappeared from the catchment at the Holocene transition, but small glaciers persisted in the mountains at the eastern lake shore. During the Early Holocene, until 8400 cal. a BP , sedimentation changed from glaciolacustrine to lacustrine and rising temperatures caused the spread of thermophilous vegetation. The Middle Holocene, until 3700 cal. a BP , comprises the regional Holocene Thermal Maximum (8000–4600 cal. a BP ) with relatively stable temperatures, denser vegetation cover and absence of mountain glaciers. Reoccurrence of mountain glaciers during the Late Holocene, until 30 cal. a BP , presumably results from a slight cooling and increased humidity. Since c . 30 cal. a BP Lake Imandra has been strongly influenced by human impact, originating in industrial and mining activities. Our results are in overall agreement with vegetation and climate reconstructions in the Kola region.

Russian-German project PLOT (Paleolimnological Transect) aims at investigating the regional responses of the quaternary climate and environment on external forcing and feedback mechanisms along a more than 6000 km long longitudinal transect crossing Northern Eurasia. The well-dated record from Lake Elgygytgyn used as reference site for comparison the local climatic and environmental histories. Seismic surveys and sediment coring up to 54 m below lake floor performed in the frame of the project on Ladoga Lake (North-West of Russia; 2013), Lake Bolshoye Shchuchye (Polar Ural; 2016), Lake Levinson-Lessing and Lake Taymyr (Taymyr Peninsula; 2016-2017), Lake Emanda (Verkhoyansk Range; 2017). Fieldwork at Polar Ural and Taymyr Peninsula was conducted in collaboration with the Russian-Norwegian CHASE (Climate History along the Arctic Seaboard of Eurasia) project. Here, we present the major results of the project obtained so far.

Here, we present new results from seismic, geological, and geochemical studies conducted in 2015–2019 in the Petrozavodsk Bay of Lake Onego, NW Russia. The aims of these investigations were to (i) to characterize the structure of Quaternary deposits and (ii) provide new evidence of modern geodynamic movements and gas-seepage in Holocene sediments. The structure of the recovered deposits was composed of lacustrine mud, silt and sands from the Holocene, limno-glacial clays (varved clays) from the Late Glacial–Interglacial Transition, and glacial deposits (till) from the Late Pleistocene. The thickness of these deposits varied in different parts of the bay. Many pockmarks created by gases escaping and reaching sediment-water interface were observed in these deposits. Such pockmarks can play a significant role in the geochemical and biological processes in the bottom sediment surface, and gases that escape might modify the physicochemical characteristics of the environment.

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In the article the issues of composition and morphology of accumulative relief in the central part of the Kola region are considered. The main role in composition of the glacial forms is determined to belong to squamous, diapir and folded laciodislocations. Regularities of spatial arrangement and morphological characteristics of the relief forms, which correspond to glaciodislocations of different types, have been defined. It is concluded that three rows of marginal formations corresponding to individual retreat stages of the last glacial cover in the Late Pleistocene were developed on the studied area. Obtained data are important to determination of dynamic features of the north sector of the White Sea Ice Stream. Moreover, they may be used as criteria to prediction of mineral-building materials. В статье рассмотрены вопросы строения и морфологии аккумулятивного рельефа в центральной части Кольского региона. Установлена ведущая роль чешуйчатых, диапировых и складчатых гляциодислокаций в строении форм ледникового генезиса. Определены закономерности пространственного расположения и морфологические характеристики форм рельефа, соответствующие гляциодислокациям разного типа. Сделан вывод о развитии в районе работ трех цепочек краевых образований, соответствующих отдельным фазам деградации последнего ледникового покрова в позднем плейстоцене. Полученные данные имеют большое значение для установления особенностей динамики северного сектора беломорского ледникового потока, а также могут быть использованы в виде критериев прогнозирования минерально-строительного сырья.