Ice-sheet variations as depicted in seismic records of the Amundsen Sea Embayment, West Antarctica

• Main Authors: Weigelt, Estella, Gohl, Karsten, Uenzelmann-Neben, Gabriele, Larter, R.
• Format: Conference Object
• Language: unknown
• Published: 2008
• Subjects: Amundsen Sea; Antarc*; Antarctic; Antarctica; Ice Sheet; Pine Island; Pine Island Glacier; West Antarctica
• Online Access: https://epic.awi.de/id/eprint/19747/; https://hdl.handle.net/10013/epic.31621

The dynamics of ice-sheets in response to climate changes becomes increasingly a focus of research. In this regard the glacial history of the Amundsen Sea sector of the West Antarctic Ice-Sheet (WAIS) is of particular interest. A potential deglaciation and collapse of the Thwaites and Pine Island glacier drainage basins alone would result in a global sea level rise of approximately 1.5 m. New multichannel seismic reflection data of high-resolution offer a record of the glacial development and processes in this area. We present a first interpretation of five seismic profiles collected in the western Amundsen Sea Embayment as part of the RV Polarstern cruise ANT-XXIII/4 (2006).The sea-floor morphology of the observed area is highly variable. Close to the present coast, a rough topography includes troughs of several 100 m depth which were probably formed by palaeo-icestreams cut through the shelf. Here, the seismic lines reveal hardly any internal sequences. Only some thin sediment pockets (< 80 ms TWT ~ 60 m) in between these steep and rugged structures can be identified.On the middle shelf and outside the troughs, the topography is generally smooth and only shows small surface undulations suggesting a quieter deposition realm which was not directly affected by ice streams. Hard surface matter as revealed in parasound sections indicates the flush away of soft sediments by melt-water streams. Such streams might have also formed the shallow and about 10 km wide channel-like structures observed at some locations.The most interesting features are pronounced northwest-dipping reflector series of more than 1 s TWT thickness (> 800 m), indicating well layered sedimentary units. The strata reveal a striking alternation of reflection-poor, almost opaque, units and sequences of closely spaced, continuous reflectors. This alternation probably represents changes in depositional conditions due to sea level variations or periods of ice-sheet extension. Reflection-poor units probably consist of a homogeneous sedimentary ...