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Allen, Claire Susannah; Pike, Jennifer; Pudsey, Carol J (2011): Sea ice diatoms from Late Quaternary sediments in the Scotia Sea. PANGAEA,, Supplement to: Allen, CS et al. (2011): Last glacial-interglacial sea-ice cover in the SW Atlantic and its potential role in global deglaciation. Quaternary Science Reviews, 30(19-20), 2446-2458,

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Sea-ice growth and decay in Antarctica is one of the biggest seasonal changes on Earth, expanding ice cover from 4x10**6 km**2 to a maximum of 19x10**6 km**2 during the austral winter. Analyses of six marine sediment cores from the Scotia Sea, SW Atlantic, yield records of sea-ice migration across the basin since the Lateglacial. The cores span nearly ten degrees of latitude from the modern seasonal sea-ice zone to the modern Polar Front. Surface sediments in the cores comprise predominantly diatomaceous oozes and muddy diatom oozes that reflect Holocene conditions. The cores exhibit similar down-core stratigraphies with decreasing diatom concentrations and increasing magnetic susceptibility from modern through to the Last Glacial Maximum (LGM). Sediments in all cores contain sea-ice diatoms that preserve a signal of changing sea-ice cover and permit reconstruction of past sea-ice dynamics. The sea-ice records presented here are the first to document the position of both the summer and winter sea-ice cover at the Last Glacial Maximum (LGM) in the Scotia Sea. Comparison of the LGM and Holocene sea-ice conditions shows that the average winter sea-ice extent was at least 5° further north at the LGM. Average summer sea-ice extent was south of the most southerly core site at the LGM, and suggests that sea-ice expanded from approximately 61°S to 52°S each season. Our data also suggest that the average summer sea-ice position at the LGM was not the maximum extent of summer sea-ice during the last glacial. Instead, the sediments contain evidence of a pre-LGM maximum extent of summer sea-ice between ab. 30 ka and 22 ka that extended to ab. 59°S, close to the modern average winter sea-ice limit. Based on our reconstruction we propose that the timing of the maximum extent of summer sea-ice and subsequent retreat by 22 ka, could be insolation controlled and that the strong links between sea-ice and bottom water formation provide a potential mechanism by which Southern Hemisphere regional sea-ice dynamics at the LGM could have a global impact and promote deglaciation.
Median Latitude: -57.031380 * Median Longitude: -42.257760 * South-bound Latitude: -60.303330 * West-bound Longitude: -48.043333 * North-bound Latitude: -52.603333 * East-bound Longitude: -36.651000
KC81 * Latitude: -56.738330 * Longitude: -42.968330 * Elevation: -3662.0 m * Recovery: 3.2 m * Location: Scotia Sea, southwest Atlantic * Device: Kasten corer (KAL)
PC287 * Latitude: -60.303330 * Longitude: -36.651660 * Elevation: -1998.0 m * Recovery: 5.75 m * Location: Scotia Sea, southwest Atlantic * Device: Piston corer (PC)
TC287 * Latitude: -60.303000 * Longitude: -36.651000 * Elevation: -1998.0 m * Location: Scotia Sea, southwest Atlantic * Device: Trigger corer (TC)
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