The grounding-zone wedge inventory on the Amundsen Sea Embayment shelf, West Antarctica: formation processes and significance for establishing reliable post-LGM retreat chronologies

• Main Authors: Klages, Johann Philipp, Kuhn, Gerhard, Hillenbrand, Claus-Dieter, Smith, James A., Graham, Alastair G. C., Gohl, Karsten, Wacker, Lukas
• Format: Conference Object
• Language: unknown
• Published: 2015
• Subjects: Amundsen Sea; West Antarctica; Antarc*; Antarctica; Ice Sheet
• Online Access: https://epic.awi.de/id/eprint/38678/; https://epic.awi.de/id/eprint/38678/1/Klages_etal_2015_Poster_Polartagung_Munich_small.pdf; https://hdl.handle.net/10013/epic.45984; https://hdl.handle.net/10013/epic.45984.d001

Grounding-zone wedges have been mapped on many of the formerly glaciated continental shelves around Antarctica. These wedges record periods of grounding-line stillstand during general ice-sheet retreat following the Last Glacial Maximum (~26-19 ka BP; kiloyears before present). The presence of grounding-zone wedges along the axis of a palaeo-ice stream trough therefore indicates a style of episodic grounding-line retreat during the migration from its initial position at the LGM to its modern position. However, precise chronological constraints for both the onset and duration of these stillstands are still lacking. Consequently, the role of grounding-zone wedge formation in modulating post-LGM ice-sheet retreat, and therefore ice sheet stability cannot be reliably quantified. Additionally, this information is also vital for calculating reliable retreat rates during the past, which are essential for evaluating and understanding the significance of modern, locally very high retreat rates. Here we present the currently known inventory of grounding-zone wedges on the Amundsen Sea Embayment shelf. We will discuss formation processes and possible relations between grounding-zone wedges in neighbouring palaeo-ice stream troughs that are separated by an inter-ice stream ridge. Furthermore, we will present our approach on how i) to reliably date the onset of stabilization periods, and ii) to constrain their actual duration. This knowledge will help refine available post-LGM retreat chronologies, which, in turn, serve as a basis for validating and improving ice-sheet models.