Submarine glacigenic debris flows, deep-sea channels and past ice-stream behaviour of the East Greenland continental margin

Abstract

Former glacigenic debris flow (GDF) and deep-sea channel build-up is shown from side-scan sonar, seismic and sediment core data of the passive continental margin of the Greenland Sea. The well-developed deep-sea channel systems cross GDF systems and point towards sediment-laden meltwater production. There is no indication for large-scale submarine sliding such as observed on several locations on the Norwegian margin, where deep-sea channels are far less frequent or do not exist whereas seabed erosion, GDF stacking and trough mouth fans dominate. The observed pattern on the East Greenland margin reflects a contrast to the Norwegian margin in paleo ice-stream extent, dynamics and type of sediment delivery. A conceptual model for ice-sheet behaviour on the continental margin of the Greenland Sea has been developed based on the characteristics, distribution and morphology of GDFs and deep-sea channels in four periods at ca 2.5 Ma, 1.5 Ma, 0.2 Ma and 25 ka. We argue that the erosional capabilities of ice streams on the NE Greenland margin indicated by aggradation versus progradation were less then those of the fast flowing ice streams of the Norwegian margin, and that the ice streams in cross-shelf troughs remained probably distal from the shelf break during the Late Weichselian.