New Data Constraints on Past Antarctic Ice Sheet Extent and Retreat in the Weddell Sea Embayment

• Main Authors: Hillenbrand, Claus-Dieter, Arndt, Jan Erik, Sørlie, S. H., Smith, J. A., Grobe, Hannes, Lamping, Nele, Wacker, Lukas, Forwick, Matthias, Dorschel, Boris, Melles, Martin, Anderson, John B., Klages, Johann Philipp, Bickert, Thorsten, Hodgson, Dominic A., Kuhn, Gerhard
• Format: Conference Object
• Language: unknown
• Published: AGU, abstract #C52B-01 2016
• Subjects: Antarc*; Antarctic; Brunt Ice Shelf; Ice Sheet; Ice Shelf; Weddell Sea
• Online Access: https://epic.awi.de/id/eprint/46206/; http://adsabs.harvard.edu/abs/2016AGUFM.C52B.01H; https://hdl.handle.net/10013/epic.cc152de2-9ef4-4c89-abb6-f6ce8730419d

The glacial history of the Antarctic Ice Sheet in the Weddell Sea embayment during the Last Glacial Maximum (LGM; 23-19 ka) is a matter of debate. Existing onshore and offshore data suggest two alternative reconstructions for the LGM ice sheet extent. One scenario shows an ice sheet grounding line that had advanced to (or at least close to) the shelf edge throughout the Weddell Sea, embayment. The other reconstruction concludes that the grounding line in the two main cross shelf troughs was located only slightly farther offshore than today. Here we present new data from multibeam swath bathymetry surveys, acoustic sub-bottom profiles and sediment cores collected during recent and past British and German marine expeditions. These data provide new constraints on the glacial history of the eastern part of the Weddell Sea embayment. A previously unknown, stacked grounding zone wedge discovered in the outer shelf part of Filchner Trough possibly marks the northernmost position of the LGM grounding line within this palaeo-ice stream trough. Crescentic moraines and a predominantly smooth seabed morphology mapped north of the Brunt Ice Shelf reveal a complex glacial history with repeated advances of grounded ice or episodic retreats, controlled by a hard seafloor substrate. We will compare new radiocarbon dates obtained from the sediment cores to existing chronologies and use them to reconstruct the timing of the last maximum ice sheet advance and post-LGM retreat. Finally, we will set our new findings into context with results from ice sheet models and discuss their implications for Antarctica's contribution to global meltwater pulses during the last deglaciation.