Within Earth's ice sheets, fast-flowing ice streams are the principal components through which ice and sediment are discharged, accounting for c. 90% of the ice lost from the Antarctic today (Bamber et al. 2000). The processes occurring at ice-stream beds, therefore, lie at the heart of resolving how and why major ice-stream systems may change in the future. Although drill-cores and ice-surface seismic methods have been employed to survey the beds of some of West Antarctica's ice streams, studies are still hampered by the logistical and technological challenges associated with understanding a dynamic and spatially extensive interface buried beneath kilometre-thick continental ice (Larter et al. 2009). Here, a multibeam swath-bathymetric dataset acquired from the Dotson–Getz palaeo-ice-stream bed, offshore of West Antarctica, is described (Fig. 1a). In contrast to the modern ice-sheet base, the spatial coverage and quality of the marine data allow us to analyse landform evolution along an entire ice-stream bed that is both completely exposed and well preserved.
Compilation of multibeam-bathymetric data from the Dotson–Getz Trough, West Antarctica. (a) Location of study area (red box; map from IBCSO v. 1.0). (b) Bathymetry of the Dotson–Getz Trough showing convergent tributaries; data from Nitsche et al. (2007). IS, ice shelf. (c) Multibeam-bathymetric data for the Dotson–Getz trough and tributary regions, collated from published datasets (UK, German, Swedish and US), illustrating the variety of seafloor landforms. (d) Profile along the trough axis showing the boundary between crystalline bedrock and seaward-dipping sedimentary strata, and a mid-trough grounding-zone wedge on the shoaling seafloor. Profile x–x′ is located in (b). VE×120.
Description of landforms
The study area in the western Amundsen Sea embayment comprises three 17–39 km wide troughs that extend seaward of the Getz and Dotson ice shelves (Fig. 1a–c). These tributary troughs converge into a single well-defined cross-shelf trough that extends for …
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