A glacier-influenced turbidite system and associated landform assemblage in the Greenland Basin and adjacent continental slope

Abstract

Evidence of the former extent and dynamics of the Greenland Ice Sheet is preserved on the continental margin of NE Greenland (Fig. 1). The continental shelf is incised by a number of deep (up to 500 m) cross-shelf troughs (Batchelor & Dowdeswell 2014; Arndt et al. 2015) (Fig. 1a), which are interpreted to have been occupied intermittently and eroded by marine-terminating ice streams during successive full-glacial periods (e.g. Dowdeswell et al. 2014). The outer continental shelf of NE Greenland was previously thought to have remained free of grounded ice during the Last Glacial Maximum (LGM) at around 20 ka, with the ice sheet restricted mainly to fjord and inner-shelf locations (Funder 1989; Funder & Hansen 1996; Bennike & Weidick 2001). However, recent geophysical and geological evidence, including streamlined submarine landforms and moraine ridges within several cross-shelf troughs, suggests that the Greenland Ice Sheet expanded across the outer-shelf beyond the NE Greenland coast, possibly to the shelf break, during the LGM (Evans et al. 2002, 2009; Winkelmann et al. 2010). Fig. 1. ( a ) Multibeam swath bathymetry of the Greenland Basin and adjacent continental slope beyond Kejser Franz Josef Trough (KFJT) and Norske Trough (NT). Dashed white lines show former ice-stream flow pathways in troughs across the continental shelf. Multibeam acquisition system Kongsberg-Simrad EM120. Frequency 12 kHz. Grid-cell size 100 m. Background bathymetry is from IBCAO v. 3.0. ( b ) Profile along the axis of the main channel in the Greenland Basin. VE×90. ( c ) Location of study area (red box; map from IBCAO v. 3.0). Dashed black lines bound major cross-shelf troughs. JMFZ, Jan Mayen Fracture Zone. Three smaller troughs are present between Kejser Franz Josef Trough and Norske Trough (Batchelor & Dowdeswell 2014). Evidence of past ice-sheet activity is not restricted to the continental shelf; landforms …