Maximum extent of the Eurasian ice sheets in the Barents and Kara Sea region during the Weichselian

Based on field investigations in northern Russia and interpretation of offshore seismic data, we have made a preliminary reconstruction of the maximum ice-sheet extent in the Barents and Kara Sea region during the Early/Middle Weichselian and the Late Weichselian. Our investigations indicate that the Barents and Kara ice sheets attained their maximum Weichselian positions in northern Russia prior to 50 000 yr BP, whereas the northeastern flank of the Scandinavian Ice Sheet advanced to a maximum position shortly after 17 000 calendar years ago. During the Late Weichselian (25 000-10 000 yr BP), much of the Russian Arctic remained ice-free. According to our reconstruction, the extent of the ice sheets in the Barents and Kara Sea region during the Late Weichselian glacial maximum was less than half that of the maximum model which, up to now, has been widely used as a boundary condition for testing and refining General Circulation Models (GCMs). Preliminary numerical-modelling experiments predict Late Weichselian ice sheets which are larger than the ice extent implied for the Kara Sea region from dated geological evidence, suggesting very low precipitation.     

Periglacial sediment variations controlled by late Quaternary climate and lake level change at Elgygytgyn Crater, Arctic Siberia

Late Quaternary sediments in a permafrost environment recovered from the Elgygytgyn Impact Crater were studied to determine regional palaeoenvironmental variability and infer past water-level changes of the crater lake. Stratigraphic analysis of a 5 m long permafrost core is based on various lithological (grain size, total organic carbon, magnetic susceptibility) and hydrochemical (oxygen isotope composition, major cation content) properties and pore ice content. The results show that alluvial sediments accumulated on top of cryogenically weathered volcanic rock. Changes in the hydrochemical properties reflect different stages of cryogenic weathering. The lithological characteristics mark the transition from an erosive site to a site with accumulation. This environmental change is linked to a relative lake level highstand at >13 000 yr BP, when a shoreline bar was formed leading to slope sedimentation. Lake level dropped by 4 m during the Holocene.     

Sediment transport to the Laptev Sea–hydrology and geochemistry of the Lena River

This study focuses on the fluvial sediment input to the Laptev Sea and concentrates on the hydrology of the Lena basin and the geochemistry of the suspended particulate material. The paper presents data on annual water discharge, sediment transport and seasonal variations of sediment transport. The data are based on daily measurements of hydrometeorological stations and additional analyses of the SPM concentrations carried out during expeditions from 1975 to 1981. Samples of the SPM collected during an expedition in 1994 were analysed for major, trace, and rare earth elements by ICP-OES and ICP-MS. Approximately 700 km³ freshwater and 27 times 10⁶ tons of sediment per year are supplied to the Laptev Sea by Siberian rivers, mainly by the Lena River. Due to the climatic situation of the drainage area, almost the entire material is transported between June and September. However, only a minor part of the sediments transported by the Lena River enters the Laptev Sea shelf through the main channels of the delta, while the rest is dispersed within the network of the Lena Delta. Because the Lena River drains a large basin of 2.5 times 10⁶ km², the chemical composition of the SPM shows a very uniform composition. In contrast, smaller rivers with more restricted catchment areas exhibit significant differences.     

Late Pleistocene and Holocene vegetation and climate on the northern Taymyr Peninsula, Arctic Russia

Pollen data from a Levinson-Lessing Lake sediment core (74°28'N, 98°38'E) and Cape Sabler, Taymyr Lake permafrost sequences (74°33'N, 100°32'E) reveal substantial environmental changes on the northern Taymyr Peninsula during the last c. 32 000 [Formula: See Text]C years. The continuous records confirm that a scarce steppe-like vegetation with Poaceae, Artemisia and Cyperaceae dominated c. 32 000-10 300 [Formula: See Text]C yr BP, while tundra-like vegetation with Oxyria, Ranunculaceae and Caryophyllaceae grew in wetter areas. The coldest interval occurred c. 18 000 yr BP. Lateglacial pollen data show several warming events followed by a climate deterioration c. 10 500 [Formula: See Text]C yr BP, which may correspond with the Younger Dryas. The Late Pleistocene/Holocene transition, c. 10 300-10 000 [Formula: See Text]C yr BP, is characterized by a change from the herb-dominated vegetation to shrubby tundra with Betula sect. Nanae and Salix. Alnus fruticosa arrived locally c. 9000-8500 [Formula: See Text]C yr BP and disappeared c. 4000-3500 [Formula: See Text]C yr BP. Communities of Betula sect. Nanae, broadly distributed at c. 10 000-3500 [Formula: See Text]C yr BP, almost disappeared when vegetation became similar to the modern herb tundra after 3500-3000 [Formula: See Text]C yr BP. Quantitative climate reconstructions show Last Glacial Maximum summer temperature about 4°C below the present and Preboreal (c. 10 000 [Formula: See Text]C yr BP) temperature 2-4°C above the present. Maximum summer temperature occurred between 10 000 and 5500 [Formula: See Text]C yr BP; later summers were similar to present or slightly warmer.