Mega-scale glacial lineations in Marguerite Trough, Antarctic Peninsula

Mega-scale glacial lineations (MSGLs) are elongate, linear to curvilinear sediment ridges that can be several tens of kilometres long and a few metres high (Clark 1993). They occur in marine and terrestrial palaeo-glacial settings and are composed of a range of sediments that are often deformed (Dowdeswell et al. 2004; O Cofaigh et al. 2013). Despite some debate surrounding their genesis (O Cofaigh et al. 2010), MSGLs are widely regarded as diagnostic indicators of the former presence of ice streams. Marguerite Trough extends across the continental shelf west of the Antarctic Peninsula (Fig. 1). The trough supported a palaeo-ice stream which drained to the shelf edge during the last glaciation. Ice streaming is recorded by subglacial bedforms along the trough (Livingstone et al. 2013), including classic examples of MSGLs up to 20 km long formed in sediment on the outer shelf (Fig. 1a–c). Fig. 1. Mega-scale glacial lineations (MSGLs) from Marguerite Trough, Antarctic Peninsula. ( a ) Multibeam shaded-relief image of MSGLs in water depths of 450–700 m on the middle and outer-shelf. ( b ) Multibeam colour shaded-relief image of grounding-zone wedge (GZW) on the outer shelf of Marguerite Trough. Note the subtle difference in the orientation of …