Did we find an ice-proximal location in the Amundsen Sea to finally reveal the last interglacial state of the West Antarctic Ice Sheet?

• Main Authors: Klages, Johann Philipp, Kuhn, Gerhard, Hillenbrand, Claus-Dieter, Smith, James A., Nitsche, Frank O., Frederichs, Thomas, Gohl, Karsten, Wacker, Lukas
• Format: Conference Object
• Language: unknown
• Published: 2018
• Subjects: Amundsen Sea; Antarctic; Last Peak; West Antarctic Ice Sheet; Antarc*; Ice Sheet; Iceberg*
• Online Access: https://epic.awi.de/id/eprint/46776/; https://hdl.handle.net/10013/epic.788a4227-da2e-4401-a027-10d5e46b5725

One of the major questions in palaeoclimate research is whether or not the West Antarctic Ice Sheet (WAIS) collapsed during the warmest phase of the last interglacial period (Marine Isotope Stage 5e; 130-116 ka). Several numerical models and sea-level reconstructions suggest such a collapse, but critically it has not been confirmed by WAIS proximal empirical data, yet. Answering this question by analyzing sedimentary sequences from the West Antarctic shelf requires areas that remained unaffected by 1) erosion by grounded ice, and 2) scouring by iceberg keels since MIS 5e. During RV Polarstern Expedition ANT-XXVI/3 in early 2010 we discovered such an area on the Amundsen Sea shelf for the first time. We demonstrate that the outermost section of the Cosgrove-Abbot palaeo-ice stream trough in the easternmost Amundsen Sea Embayment was not covered by grounded ice during the last glacial period, and that a part of this area was largely protected from iceberg scouring by its large water depth and a grounding zone wedge located further landward. We present combined geophysical and geological data revealing this unique location at which the state of the WIAS during the last peak interglacial may be reconstructed, and give an outlook on how this could be achieved.