Grounding-zone wedges on the western Svalbard shelf

Abstract

When ice sheets decay and retreat across continental shelves during regional deglaciation, the glacial landforms preserved on the seafloor provide evidence of the nature and rate of change. The presence of streamlined sedimentary landforms implies that fast-flowing ice streams drained a full-glacial ice sheet that extended across the continental shelf (e.g. Ottesen et al. 2005). By contrast, observations of sedimentary depocentres such as grounding-zone wedges (GZWs; Dowdeswell & Fugelli 2012; Batchelor & Dowdeswell 2015) in cross-shelf troughs are a clear indicator that halts in ice-sheet retreat, perhaps lasting centuries during which ice remained active delivering sediment to the grounding zone, took place between episodic phases of more rapid terminus retreat. The continental shelf west of Svalbard contains a number of sedimentary depocentres or wedges that are orientated across troughs, transverse to the direction of former ice flow (Fig. 1) (e.g. Ottesen et al. 2007; Forwick & Vorren 2010). Multibeam images of three sedimentary wedges are shown in Figure 1a–c. The wedges extend c. 5–20 km across the two fjords. Each …