A set of grounding-zone wedges in Vestfjorden, North Norway

Abstract

At the Last Glacial Maximum (LGM), a 400 km long fast-flowing ice stream drained an interior basin of the Scandinavian Ice Sheet of about 150 000 km2 through Vestfjorden and the adjacent cross-shelf trough of Traenadjupet further downstream (Fig. 1) (Ottesen et al. 2005 a ). Evidence for past ice-stream activity comes from a variety of submarine sedimentary landforms that are streamlined in the direction of past ice flow (Ottesen et al. 2005 b ). Superimposed on these streamlined landforms are several wedge-like sedimentary features orientated transverse to flow. These submarine landforms suggest that deglacial retreat was punctuated by stillstands that produced substantial depocentres known as grounding-zone wedges (GZWs) (e.g. Anderson 1999; Dowdeswell et al. 2008; Dowdeswell & Fugelli 2012; Batchelor & Dowdeswell 2015). Fig. 1. Grounding-zone wedges in Vestfjorden, North Norwegian margin. ( a ) Shaded-relief swath-bathymetric image of a 5500 km2 area of Vestfjorden showing two large GZWs which both override MSGLs and have further MSGLs on their surfaces. The shallowest parts of the GZWs have been affected by the ploughing action of iceberg keels. Acquisition system Kongsberg EM100. Frequency 97 kHz. Grid-cell size 50 m. ( b …