Enigmatic needle-like seafloor features in the Bear Island Trough, central Barents Sea

Mapping of well-preserved submarine glacial landforms has been used to decipher the pattern and dynamics of the retreat of the Bear Island Trough ice stream that drained the Barents Sea Ice Sheet during the Late Weichselian deglaciation (e.g. Andreassen et al. 2008, 2014; Winsborrow et al. 2010; Ruther et al. 2011; Bjarnadottir et al. 2014). However, the formation processes of some of the landforms identified are not fully understood; one example is that of an enigmatic linear sedimentary seafloor feature termed ‘needle’ by Bjarnadottir et al. (2014). A variety of subglacial landforms co-exist in the Bear Island Trough (BIT), including landforms typically associated with both active ice streams, such as mega-scale glacial lineations (MSGLs) and grounding-zone wedges (GZWs), and ice stagnation (e.g. Ruther et al. 2011; Andreassen et al. 2014; Bjarnadottir et al. 2014). Included among these are remarkably straight and elongate features, termed ‘needles’ by Bjarnadottir et al. (2014), which are described here. Needle-like features occur in the upper BIT at water depths of 230–280 m (Fig. 1a). They are <40 km long, <700 m wide and protrude <40 m from …