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Submarine Geomorphology of the Continental Shelves of Southeast and Southwest Greenland from Olex Data



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Ryan, Jonathan 


Mass loss from the Greenland Ice Sheet remains the largest uncertainty in projections of sea level rise for the 21st century. Reconstructing the former history of the Greenland Ice Sheet during the Late Quaternary provides important constraints on how the ice sheet will behave in response to future environmental change. In order to improve our understanding of the extent, dynamics and deglacial retreat of the Greenland Ice Sheet during and after the Last Glacial Maximum (LGM), this study used geophysical bathymetric data to investigate the geomorphology of the continental margins of Southern Greenland. In particular, Olex data, which consist of multiple single-beam echo-sounder lines, were utilised. Turbidity current-channel systems and gullies on the continental slopes, and moraines on the continental shelf edge of Southern Greenland indicate that the Greenland Ice Sheet extended to the continental shelf edge during the LGM. Drumlins and crag-and-tails, located in troughs, suggest that twenty ice streams drained the ice sheet in Southern Greenland at this time. After the LGM, the deglacial response of the Greenland Ice Sheet was spatially variable. Grounding-zone wedges in some troughs suggest that ice sheet retreat was punctuated by still-stands. In other troughs, the absence of sedimentary depocentres indicates that ice sheet retreat was rapid. In Southeast Greenland, iceberg ploughmarks suggest that initial retreat from the shelf edge was characterised by the calving of deep-keeled icebergs. In contrast, gullying offshore of inter-ice stream areas and evidence of meltwater sedimentation in Southwest Greenland, indicate that initial deglaciation was characterised predominantly by surface melting.






Master of Philosophy (MPhil)

Awarding Institution

University of Cambridge