Geomorphological and sedimentological evidence of past Greenland Ice Sheet advance and retreat on the continental shelf offshore of SE Greenland as revealed by ‘Kang-Glac’ cruise SD041

Cruise SD041 of the UK research vessel the RRS Sir David Attenborough to the continental shelf offshore of SE Greenland took place in July-August 2024. The cruise was part of the UK NERC-funded ‘Kang-Glac’ project, a large multi-disciplinary, international, research project jointly led by British Antarctic Survey and Durham University, UK. The cruise collected a range of geological, geophysical, oceanographic and biological data from the continental shelf offshore of Kangerlussuaq Fjord, SE Greenland, and in several adjoining fjords. The aim of the Kang-Glac project is to investigate the response of the Greenland Ice Sheet to ocean warming during the last 11,700 years of the Holocene. During the cruise marine geophysical data in the form of multibeam swath bathymetric imagery of seafloor landforms and sub-bottom profiler data of shallow acoustic stratigraphy were collected, in addition to a suite of sediment cores. Data collection targeted a large cross-shelf bathymetric trough (‘Kang-Trough’) which extended from the mouth of Kangerlussuaq Fiord to the edge of the continental shelf, as well as a series of smaller fjords to the northeast. These marine geophysical data and sediment cores provide a clear record of an extensive Greenland Ice Sheet (GrIS) which expanded and retreated across the shelf via Kang-Trough. Landforms comprise well developed streamlined subglacial bedforms which show convergent GrIS flow into the trough, as well as occasional transverse moraines recording episodic retreat. Sediment cores recovered subglacial tills recording a grounded ice sheet in the cross-shelf trough overlain by a range of deglacial glacimarine facies recording retreat by melting and iceberg calving. Cores from the adjacent trough mouth fan on the continental slope targeted glacigenic debris flows which likely were deposited when the GrIS was grounded at the shelf edge and delivered glacigenic debris onto the slope. Collectively the data provide new insights into past GrIS extent, dynamics, and the nature of associated glacigenic sediment delivery from the LGM through the Holocene in the SE sector of the Greenland continental margin.