Description: Detailed investigations of the distribution of clay minerals of Late Glacial-Holocene sediments from the SW Barents Sea provide important new information about the provenance and transport paths of the sediments. This information leads to better understanding of the onset of the last deglaciation and subsequent advances/retreats of the Barents Sea- and Fennoscandian Ice Sheets. The results show interaction and changes in the Fennoscandian Ice Sheet and Bj0rn0yrenna Ice Stream during the last deglaciation. High illite content and maximum kaolinite content (〉18700 cal yr B.P.) indicate glacial erosion from both the Fennoscandian Ice Sheet and Bjornoyrenna Ice Stream (LGM II). The occurrence of a C. reniforme dominated benthic foraminiferal assemblage (~18700 cal yr B.P.) indicates that the northern most cores site in Ingoydjupet had already been deglaciated and was probably situated in a glacier distal environment. In addition, smectite content reaching its highest level, concurrent with the presence of Neogloboquadrina pachyderma (sin) dominated planktic foraminifera can be related to the strengthening of the Atlantic Current. The inflow of the Atlantic Water may have triggered deglaciation of the Fennoscandian Ice Sheet (Bolling interstadial). A rapid increase in illite content, reflecting strong melting of the Fennoscandian Ice Sheet (~15 000 cal yr B.P.), indicates the onset of deglaciation in a core closer to the continent. Decrease of illite and IRD content, together with the deposition of laminated sediments during the Older Dryas stadial (15000-14000 cal yr B.P.) indicates colder conditions and formation of at least seasonal sea-ice. In addition, increased kaolinite content indicates increased glacial erosion of the Bjornoyrenna Ice Stream. The highest values of illite content and increased IRD content (14000-13000 cal yr B.P.) can be related to strong melting of the Fennoscandian Ice Sheet. A slight indication of the Younger Dryas cold period is given by the decrease in illite and IRD contents. All clay contents are more stable during Holocene compared to LGM and the last deglaciation.

Description: The origin of two acoustic sediment units has been studied based on lithological facies, chronology and benthic stable isotope values as well as on foraminifera and clay mineral assemblages in six marine sediment cores from Kveithola, a small trough west of Spitsbergenbanken on the western Barents Sea margin. We have identified four time slices with characteristic sedimentary environments. Before c. 14.2 cal. ka, rhythmically laminated muds indicate extensive sea ice cover in the area. From c. 13.9 to 14.2 cal. ka, muds rich in ice-rafted debris were deposited during the disintegration of grounded ice on Spitsbergenbanken. From c. 10.3 to 13.1 cal. ka, sediments with heterogeneous lithologies suggest a shifting influence of suspension settling and iceberg rafting, probably derived from a decaying Barents Sea Ice Sheet in the inner-fjord and land areas to the north of Kveithola. Holocene deposition was episodic and characterized by the deposition of calcareous sands and shell debris, indicative of strong bottom currents. We speculate that a marked erosional boundary at c. 8.2 cal. ka may have been caused by the Storegga tsunami. Whilst deposition was sparse during the Holocene, Kveithola acted as a sediment trap during the preceding deglaciation. Investigation of the deglacial sediments provides unprecedented details on the dynamics and timing of glacial retreat from Spitsbergenbanken.

Description: The Ocean Drilling Program Leg 188 Site 1165 was drilled on the Wild Drift on the Continental Rise off Prydz Bay, East Antarctica to a total depth of 999.1 meters below seafloor (mbsf). It recovered an extensive suite of terrigenous and hemipelagic sediments of early Miocene to Pleistocene age. Of special interest in this study is the sediment column between 0 and 50 mbsf, which consists of a well-preserved section of Pliocene-Pleistocene-age sediments that was sampled at 10-cm intervals. Multiproxy study of this interval could show possible intervals of expansions of the ice-sheet across the continental shelves and express the climatic evolution in Antarctica, particularly during the 'middle' Pliocene warm period (3.15 to 2.85 Ma) which may provide an indication of how the Earth responds to a rise of its surface temperature. According to the existing age model, the upper 50 mbsf stratigraphic sequence of Site 1165 reaches back to ~4.9 Ma. Throughout this interval, the clay-mineral content is characterized by fluctuations of individual clay minerals, particularly smectite and chlorite. The smectite concentration varies mainly between 0% and 30%. Illite fluctuates less between 50% and 80%, and kaolinite varies mainly between 10% and 20%. Chlorite concentrations are mainly 0% to 10%. There is also a noticeable change in magnetic susceptibility at ~34 mbsf that is clearly indicated in the composition of the clay-mineral suite. At this level, smectite decreases and illite, kaolinite and chlorite show some variability. In particular, there is a slight but persistent increase in chlorite. The results from the Plio-Pleistocene transition, with evenly fluctuating smectite and illite contents and the gradually increasing chlorite content, may indicate cooler conditions compared to the mid-Pliocene conditions. Slight increase in illite content and decrease in smectite content towards Pleistocene supports the previous assumption. The results from the mid-Pliocene with the increasing smectite content and decreasing illite content may indicate warmer and possibly interglacial conditions.