Sedimentology on cores off Filchner Shelf Ice, Weddell Sea, Antarctica

• Main Authors: Wessels, Martin, Fütterer, Dieter K, Grobe, Hannes
• Format: Dataset
• Language: English
• Published: PANGAEA 1989
• Subjects: ANT-II/4; ANT-IV/3; AWI_Paleo; Filchner Shelf; Giant box corer; GKG; Gravity corer (Kiel type); Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Polarstern; PS04; PS04/318; PS04/334; PS04/335; PS04/337; PS04/340; PS04/346; PS04/348; PS04/350; PS04/351; PS04/357; PS04/433; PS04/434; PS04/472; PS08; PS08/379; PS08/380; PS08/381; PS08/382; PS08/452; PS1194-1; PS1196-1; PS1197-1; PS1197-2; PS1198-1; PS1199-1; PS1199-2; PS1200-2; PS1200-4; PS1201-1; PS1210-1; PS1210-2; PS1214-1; PS1396-1; PS1397-1; PS1397-3; PS1398-1; PS1398-2; PS1399-1; PS1424-1; PS1424-2; Berkner Bank; Berkner Island; Ronne Ice Shelf; Weddell; Weddell Sea; Antarc*; Antarctica; Filchner Ronne Ice Shelf; Filchner-Ronne Ice Shelf; Ice Sheet; Ice Shelf; Ice Shelves
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.701301; https://doi.org/10.1594/PANGAEA.701301

The sediments of 14 box cores and 7 gravity cores, mainly taken directly in front of the Filchner(-Ronne) ice shelf northwest of Berkner Island (Weddell Sea), allowed to distinguish six sediment types. On the one hand,the retreat of the at first grounded and then floated ice from the last glacial maximum is documented. On the other hand,the sediments give an insight into extensive Holocene sediment deposition and remobilization northwest of Berkner Island. The ortho till was deposited directly by the grounded ice sheet and is lacking any marine influence. After floating of the ice shelf, partly very weIl stratified, partly unstratified, non-bioturbated paratill is deposited beneath the ice shelf. Lack of IRD-content in the paratill immediately above the orthotill indicates freezing at the bottom of the ice, at least for a short period after the ice became afloat. The orthotill and paratill contain small amounts of fragmented Tertiary diatoms, which allow the conclusion, that glacial-marine sediments in the accumulation area of the Ronne ice shelf will be eroded and later deposited by ice in the investigation area. Starting of bioturbation and therefore change in sedimentation from paratill to bioturbated paratill,is caused by the retreat of the ice shelf to its actual position. Isostatic uplift of the sea-bed after the Ice Age causes minor water depths with higher current velocities. The fine-fraction is eroding and mean particle-size will increase. Maybe, also isostatic uplift is responsible for repeated great advances of the floated ice shelf as shown in an erosional horizon in some cores containing bioturbated paratill. Postglacial sediment-thicknesses exceed 3 m. Assuming floating of the ice 15.000 YBP, accumulation rates reach nearly 20cm/lOOO years. Following the theories about sediment input in front of wide ice shelves, this was not expected. In the shallower water depths of Berkner Bank, the oscillations of the ice shelf are recorded in the sediments. Sorting and redistribution by high current ...