Last Glacial ice-sheet dynamics offshore NE Greenland – a case study from Store Koldewey Trough

• Main Authors: Olsen, Ingrid Leirvik, Forwick, Matthias, Laberg, Jan Sverre, Rydningen, Tom Arne, Husum, Katrine
• Format: Text
• Language: English
• Published: 2020
• Subjects: Germania Land; Greenland; Store Koldewey; Germania land; glacier; Ice Sheet; Koldewey island; Store koldewey
• Online Access: https://doi.org/10.5194/tc-2019-281; https://tc.copernicus.org/preprints/tc-2019-281/

New swath bathymetry and high-resolution seismic data, supplemented with multi-proxy analyses of sediment gravity cores from Store Koldewey Trough, NE Greenland, support the presence of a shelf-break terminating Greenland Ice Sheet (GIS) on the northeastern part of the Greenland Margin during the Last Glacial Maximum (LGM). The presence of mega-scale glacial lineations and a grounding zone wedge in the outer part of the trough provides evidence of the expansion of fast-flowing, grounded ice, probably originating from the area presently covered with the Storstrømmen ice stream and cutting across Store Koldewey Island and Germania Land. Multiple halts and/or readvances interrupted the deglaciation. Two sets of crevasse-squeezed ridges in the outer and middle part of the trough may indicate repeated surging of the GIS during the deglaciation. The complex landform assemblage in Store Koldewey Trough is suggested to reflect a relatively slow and stepwise retreat during the deglaciation. Thus, the ice retreat probably occurred asynchronously relative to other ice streams offshore NE Greenland. Subglacial till fills the trough, with an overlying thin drape of maximum 2.5 m thickness of glacier proximal and glacier distal sediment. At a late stage of the deglaciation, the ice stream retreated across Store Koldewey Island and Germania Land, terminating the sediment input from this sector of the GIS to Store Koldewey Trough.