Repeated ice streaming on the northwest Greenland shelf since the onset of the Middle Pleistocene Transition

• Main Authors: Newton, Andrew M. W., Huuse, Mads, Knutz, Paul C., Cox, David R., Brocklehurst, Simon H.
• Format: Text
• Language: English
• Published: 2019
• Subjects: Greenland; Melville Bugt; Ice Sheet; Melville bugt
• Online Access: https://doi.org/10.5194/tc-2019-268; https://tc.copernicus.org/preprints/tc-2019-268/

Ice streams provide a fundamental control on ice sheet discharge and depositional patterns along glaciated margins. This paper investigates ancient ice streams by presenting the first 3D seismic geomorphological analysis of a major glacigenic succession offshore Greenland. In Melville Bugt, northwest Greenland, five sets of buried landforms have been interpreted as mega-scale glacial lineations (MSGL) and this record provides evidence for extensive ice streams on outer palaeo-shelves. A gradual change in mean MSGL orientation and associated depocentres suggests that the palaeo-ice flow and sediment transport pathways migrated in response to the evolving submarine topography. The stratigraphy and available chronology shows that the MSGL are confined to separate stratigraphic units and were most likely formed during several glacial stages since the onset of the Middle Pleistocene Transition at ~ 1.3 Ma. The ice streams in Melville Bugt were as extensive as elsewhere in Greenland during this transition, but, by the glacial stages of the Middle and Late Pleistocene, the ice streams in Melville Bugt appear to have repeatedly reached the palaeo-shelf edge. This suggests that the ice streams that occupied Melville Bugt during the Middle and Late Pleistocene were more active and extensive than elsewhere in Greenland. High-resolution buried 3D landform records such as these have not been previously observed anywhere on the Greenland shelf margin and provide a crucial benchmark for testing how accurately numerical models are able to recreate past configurations of the Greenland Ice Sheet.