Grounding-zone wedges on the northern Larsen shelf, Antarctic Peninsula

Abstract

Prominent quasi-linear or lobate wedge-shaped sedimentary landforms, termed grounding-zone wedges (GZWs), are distributed widely on polar continental shelves. They are regarded as a product of the deposition of mainly subglacially transported sediment at the grounding zone of modern and palaeo ice sheets and ice streams (e.g. Shipp et al. 1999; Ottesen et al. 2005; Horgan et al. 2013). GZWs vary in shape, dimension and regional distribution across continental shelves, forming single or multiple and widely or closely spaced bedforms. The presence of these landforms is used to delimit the maximum and retreat positions of former ice-sheet grounding-zones (e.g. Shipp et al. 1999; Ottesen et al. 2005). During the Late Glacial transition, retreat of the Antarctic Peninsula Ice Sheet produced several distinctive grounding-zone landforms (Evans et al. 2005). Well-defined ramp-scarp, wedge-shaped bathymetric features are present in several places across the northern Larsen shelf south of Larsen Inlet and east of the deepest part of Greenpeace Trough, NE Antarctic Peninsula (Fig. 1a–h). The landforms are found at water depths of 510–580 m, are spaced c. 6 km or more apart and are up to 15–20 km long, 10–18 m high and …