Description: The sediment succession of Lake Imandra in the central Kola region was investigated by a hydro-acoustic survey followed by sediment coring of site Co1410 (67°42'56.76"N, 33°5'6.42"E) down to the acoustic basement. We reconstructed the environmental history of Lake Imandra after the last deglaciation based on physical, biogeochemical, sedimentological, granulometrical, and micropalaeontological proxies. Our findings reveal the timing of the onset of lacustrine sediment deposition in the lake basin during the Late Glacial and the variability of climatic signals throughout the Holocene. All datasets comprise a depth and age column and: 1. S = Sulfur (%); TOC = Total Organic Content (%); TOC/TN = Total Organic Content / Total Nitrogen; Water Content (%); Grain Size d50 (µm); EM1 =Endmember 1 (%); EM2 =Endmember 2 (%); EM3 = Endmember 3 (%) 2. Acroperus harpae; Alona affinis; Alona guttata/Coronatella rectangula; Alona intermedia; Alona quadrangularis; Alona rustica; Alonella excisa; Alonella exigua; Alonella nana; Alonopsis elongata; Bosmina (Bosmina) longirostris; Bosmina (Eubosmina) cf. longispina/cf. coregoni; Chydorus cf. sphaericus; Daphnia longispina agg.; Eurycercus sp. Leptodora kindtii; Monospilus dispar; Paralona pigra; Pleuroxus truncatus; Rhynchotalona falcata; Planktonic; Littoral-benthic ; (%) Acroperus harpae; (%) Alona affinis; (%) Alona guttata/Coronatella rectangula; (%) Alona intermedia; (%) Alona quadrangularis; (%) Alona rustica; (%) Alonella excisa; (%) Alonella exigua; (%) Alonella nana; (%) Alonopsis elongata; (%) Bosmina (Bosmina) longirostris; (%) Bosmina (Eubosmina) cf. longispina/cf. coregoni; (%) Chydorus cf. sphaericus; (%) Daphnia longispina agg.; (%) Eurycercus sp.; (%) Leptodora kindtii; (%) Monospilus dispar; (%) Paralona pigra; (%) Pleuroxus truncatus; (%) Rhynchotalona falcata 3. magnetic susceptibility (SI * 10^-5) 4. Pinus(%); Artemisia (%); Total Pollen Concentration /1000; AP/NAP; Arboreale Pollen (%); Non-Arboreale Pollen (%) 5. Zr/Rb (log); Rb/Sr; Zr/Al; K/Al; Ti (cps); Ti/Al; Si (cps); Si/Ti; Br/Al; Fe (cps); Fe/Mn

Description: A numerical ice-sheet model was used to reconstruct the Late Weichselian glaciation of the Eurasian High Arctic, between Franz Josef Land and Severnaya Zemlya. An ice sheet was developed over the entire Eurasian High Arctic so that ice flow from the central Barents and Kara seas toward the northern Russian Arctic could be accounted for. An inverse approach to modeling was utilized, where ice-sheet results were forced to be compatible with geological information indicating ice-free conditions over the Taymyr Peninsula during the Late Weichselian. The model indicates complete glaciation of the Barents and Kara seas and predicts a “maximum-sized” ice sheet for the Late Weichselian Russian High Arctic. In this scenario, full-glacial conditions are characterized by a 1500-m-thick ice mass over the Barents Sea, from which ice flowed to the north and west within several bathymetric troughs as large ice streams. In contrast to this reconstruction, a “minimum” model of glaciation involves restricted glaciation in the Kara Sea, where the ice thickness is only 300 m in the south and which is free of ice in the north across Severnaya Zemlya. Our maximum reconstruction is compatible with geological information that indicates complete glaciation of the Barents Sea. However, geological data from Severnaya Zemlya suggest our minimum model is more relevant further east. This, in turn, implies a strong paleoclimatic gradient to colder and drier conditions eastward across the Eurasian Arctic during the Late Weichselian.

Description: 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 17000 calendar years ago. During the Late Weichselian (25 000-10000 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.

Description: The sedimentological analyses of 23 undisturbed box core surface sampIes as weIl as 5 gravity cores and 22 box cores from the Crary Trough (southeastern Weddell Sea) allows the subdivision of the sediments into six types which can be related to different depositional conditions. The formation of the sediment types depend upon the position to the ice masses, the sediment input from the ice, and the temperatures and current velocities of the water masses. During the last glacial period, an orthotill was deposited beneath the grounded ice. The sediment is overcompacted, very badly sorted, contains no fossils, is not bioturbated, and is unstratified. The distribution of the orthotill in the cores in the research area shows that the ice shelf was completely grounded in Crary Trough at this period. ff