The deglaciation of the NW Barents Sea – new insights from swath-bathymetry and sub-bottom profiler data from east of the Svalbard archipelago.

With the decay of marine-based ice sheets observed today, e.g. in Antarctica and Greenland, there is a pressing need also for an improved understanding of marine paleo-ice sheets and their decay, as they provide critical constraints for a better understanding of the dynamics of modern ice sheets and their future behavior.Here we present new multi-beam swath-bathymetry and high-resolution Topas seismic data from the NW Barents Sea acquired during the Nansen Legacy (https://arvenetternansen.com/) Paleo-cruise in 2018, which provide new insights on the deglaciation history of the marine based Svalbard-Barents Sea Ice Sheet. Previous multi-beam data from the straits and troughs east of the Svalbard archipelago provided unclear or even conflicting evidence of full-glacial flow; i) eastwards, through the Erik Eriksen Strait and its eastward continuation, terminating in the Franz Victoria Trough, and ii) northwards through the Kvitøya Trough (Dowdeswell et al., 2010; Hogan et al., 2010).The new data provide evidence of a dynamic ice-sheet retreat during the deglaciation of the Erik Eriksen Strait and its eastern extension. A succession of superposing transverse ridges with a zig-zag like morphology characterize the eastern part of the mapped area. These ridges are interpreted to be recessional push-moraines, resulting from several smaller re-advances of the ice front during overall retreat through this part of the strait. To the west, ridges are buried by a ~40 m high and 20 km long sedimentary wedge, characterized by a smooth surface. The internal seismic configuration of the wedge is transparent. This sediment accumulation is interpreted to be a grounding zone wedge that likely formed during a major eastward oriented re-advance of the Svalbard-Barents Sea Ice Sheet during the deglaciation, burying some of the older recessional push-moraines. Thus, the eastward flow previously identified may be due to a major re-advance during the deglaciation rather than formed during full-glacial conditions.A ~3 msec thick layer of acoustically transparent sediments covering the grounding zone wedge and the recessional push-moraines, has been ground-truthed by gravity cores, both in front (east) of, and on top of the wedge. Radiocarbon dating will provide a minimum age for the formation of the glacial landforms, and thus add to our knowledge on the timing and dynamics of the retreat of this marine-based sector of the Svalbard-Barents Sea Ice Sheet following the Last Glacial Maximum, and this will enable improved modelling of this marine-based ice sheet.References:Dowdeswell, J.A., Hogan, K.A., Evans, J., Noormets, R., Ó Cofaigh, C., and Ottesen, D. (2010). Past ice-sheet flow east of Svalbard inferred from streamlined subglacial landforms. Geology, 38(2), 163-166.Hogan, K.A., Dowdeswell, J.A., Noormets, R., Evans, J., Cofaigh, C.Ó., and Jakobsson, M. (2010). Submarine landforms and ice-sheet flow in the Kvitøya Trough, northwestern Barents Sea. Quaternary Science Reviews, 29(25), 3545-3562. [ABSTRACT FROM AUTHOR]