Age determination of sediment cores of the southeastern Weddell Sea, Antarctica

• Main Authors: Weber, Michael E, Bonani, Georges, Fütterer, Dieter K
• Format: Dataset
• Language: English
• Published: PANGAEA 1994
• Subjects: ANT-VI/3; ANT-VIII/5; AWI_Paleo; Gravity corer (Kiel type); Halley Bay; Lyddan Island; Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Polarstern; PS12; PS12/319; PS1599-3; PS16; PS16/409; PS16/410; PS1789-1; PS1790-1; SL; Weddell; Weddell Sea; Antarc*; Antarctica
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.729813; https://doi.org/10.1594/PANGAEA.729813

On the continental margin of the southeastern Weddell Sea, Antarctica, several channel-ridge systems can be traced on the eastern side of the Crary Fan. Swath mapping of the bathymetry reveals three southwest-northeast trending ridges up to 300 m high with channels on their southeastern side. The structures occur on a terrace of the continental slope in water depths of 2000 - 3300 m. We carried out sedimentological studies on cores from three sites. Two of the studied cores are from ridges, one is from the northwestern part of the terrace. The stratigraphy of the recovered sediments is based on accelerator mass spectrometer 14C determinations, stable oxygen and carbon isotopes analyses and paleomagnetic measurements. The sediments represent a period from the last glacial maximum (LGM) to recent time. They are composed predominantly of terrigenous components. We distinguish four different sedimentary facies and assign them to processes controlling sedimentation. Microlaminated muds and cross-stratified coarse-silty sediments originated from contour currents. Bioturbated sediments reflect the increasing influence of hemipelagic sedimentation. Structureless sediments with high contents of ice-rafted debris characterize slumps. The inferred contour currents shaping the continental slope during the LGM were canalized within the channels and supplied microlaminated mud to the western sedimentary ridges due to deflection to the left induced by the Coriolis force. The lamination of the sediments is attributed to seasonal variations of current velocities. The thermohaline bottom currents were directed to the northeast and hence opposite to the Weddell Gyre. Cross-stratified coarse-silty contourites on the ridges are intercalated with the muds and indicate spillover of faster thermohaline flows. Average sedimentation rates on the terrace of the continental slope were unusually high (250 cm/ka) during the LGM, indicating active growth phases of the Crary Fan during glacial intervals. A substantial environmental change at ...