New details about the LGM extent and subsequent retreat of the West Antarctic Ice Sheet from the easternmost Amundsen Sea Embayment shelf

• Main Authors: Klages, Johann Philipp, Hillenbrand, Claus-Dieter, Smith, James A., Kuhn, Gerhard, Graham, Alastair G. C., Nitsche, Frank O., Frederichs, Thomas, Arndt, Jan Erik, Gebhardt, Catalina, Zindler, Robin, Uenzelmann-Neben, Gabriele, Gohl, Karsten, Jernas, Patrycja Ewa, Wacker, Lukas, PS104, Shipboard Scientific Party
• Format: Conference Object
• Language: unknown
• Published: 2017
• Subjects: Antarctic; Amundsen Sea; West Antarctic Ice Sheet; Antarc*; Ice Sheet
• Online Access: https://epic.awi.de/id/eprint/46093/; https://epic.awi.de/id/eprint/46093/1/Poster.pdf; https://hdl.handle.net/10013/epic.25602a21-eb90-4496-901a-0d140bdae3b2; https://hdl.handle.net/

In recent years several previously undiscovered grounding-zone wedges (GZWs) have been described within the Abbot-Cosgrove palaeo-ice stream trough on the easternmost Amundsen Sea Embayment shelf. These GZWs document both the Last Glacial Maximum (LGM; 26.5-19 cal. ka BP) grounding-line extent and the subsequent episodic retreat within this trough that neighbors the larger Pine Island-Thwaites trough to the west. Here we combine bathymetric, seismic, and geologic data showing that 1) the grounding line in Abbot Trough did not reach the continental shelf break at any time during the last glacial period, and 2) a prominent stacked GZW constructed from six individual wedges lying upon another was deposited 100 km upstream from the LGM grounding-line position. The available data allow for calculating volumes for most of these individual GZWs and for the entire stack. Sediment cores were recovered seawards from the outermost GZW in the trough, and from the individual wedges of the stacked GZW in order to define the LGM grounding-line extent, and provide minimum grounding-line retreat ages for the respective positions on the stacked GZW. We present implications of a grounded-ice free outer shelf throughout the last glacial period. Furthermore, we assess the significance of the grounding-line stillstand period recorded by the stacked GZW in Abbot Trough for the timing of post-LGM retreat of the West Antarctic Ice Sheet from the Amundsen Sea Embayment shelf.