Deglaciation and Holocene paleoceanography of the northeast Greenland Shelf

The broad continental shelf offshore northeast Greenland features large trough systems and glacial landforms indicating the presence of fast flowing ice streams in the past. The Greenland Ice Sheet clearly extended hundreds of kilometers east of its present margin during the Last Glacial Maximum, but little is known about the maximum extent and timing of deglaciation of this region. The oceanography on the shelf is characterized by Polar surface waters coming from the Arctic Ocean underlain by warmer Atlantic Water of mixed origin. A part of the Atlantic-sourced water simply crossed the Fram Strait after branching of the North Atlantic Current, while other water was recirculated at depth along the margins of the Arctic Ocean. Today, deep cross-shelf troughs allow the Atlantic Water to reach and influence the calving margins of marine-terminating glaciers of the Northeast Greenland Ice Stream, but past variability of the warm bottom waters is mostly unknown.

Here we present results of analyses of several marine sediment cores and shallow seismic data acquired from the region. The cores were collected from various localities on the 300 km-wide continental shelf between 75 - 80 °N, and most cores capture a sequence of deglacial to Holocene sediments. Analyses of the sediments include detailed chronologies, sedimentological, geochemical, and micropaleontological investigations. Evidence suggests that the Greenland Ice Sheet did not extend to the shelf break at all locations, and that influx of warm Atlantic Water played a major role during the retreat phase of the ice margin.