International Geologiical Congress - Oslo 2008


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AAB-01 Arctic and Antarctic records of deglaciation since the Last Glacial Maximum: Processes, timing and causes


New information on the deglacial history of the northern Barents Sea from marine data


Kelly Hogan, Scott Polar Research Institute (United Kingdom)
Julian Dowdeswell, Scott Polar Research Institute (United Kingdom)


In August 2006 a geophysical cruise to the continental shelf east and north of Svalbard successfully collected an extensive dataset of swath bathymetric and sub-bottom profiler data as well as 23 gravity cores. We present interpretations of these data and consider the ice dynamics of the former ice sheet and their implications for ice sheet distribution in the northern Barents Sea.
As full glacial conditions were reached between 25 and 15ka, grounded ice expanded across the inner and outer continental shelf. Swath bathymetric and shallow seismic records close to Kong Karls Land reveal a variety of morphological features including megaflutes (15m high, >5km long), drumlinised forms, sediment lobes, and ridge systems created by the Svalbard Barents Sea Ice Sheet (SBSIS). The spatial distribution and absolute orientations of these bedforms suggest that there was an ice divide between Kong Karls Land and Kvitøya. Ice flowed north through the Kvitøya Trough approaching the shelf break, and east through the bathymetric depressions that flank Kong Karls Land, most likely draining in to the Franz Victoria Trough. Streamlined, elongate sedimentary and bedrock bedforms in the troughs suggest that they may have been occupied by faster flowing ice. Compared with regional uplift models these new marine data point towards an ice centre located further west than was previously thought.
Sometime after 15ka climatic warming promoted instability of the SBSIS and it began to decay. Sediment core data and acoustic records from the outer shelf identify thin deglacial sequences of massive or laminated muds overlying glacial diamicton, indicating that initial ice sheet decay was likely rapid. The outer part of the Kvitøya Trough was apparently ice free by 14ka, which is slightly older than deglacial dates from the larger Franz Victoria Trough. On the inner shelf, moraine systems suggest that ice decay was more gradual once the ice margin had retreated to a position close to the landmasses of Nordaustlandet, Edgeøya and Barentsøya. Radiocarbon dates from marine sediment cores suggest that the seabed features are associated with a grounded ice sheet on this margin during the Last Glacial Maximum, however, further chronological control on these data is desired.


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