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Glacialmarine records of Pliocene to Holocene ice and ocean dynamics along the East Antarctic coast

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Diekmann, B. , Borchers, A. , Esper, O. , Frederichs, T. , Gersonde, R. , Grobe, H. , Hockun, K. , Hubberten, H. W. , Kretschmer, S. , Kuhn, G. , Mollenhauer, G. and Voigt, I. (2010): Glacialmarine records of Pliocene to Holocene ice and ocean dynamics along the East Antarctic coast , International Polar Year, Oslo Science Coference. .
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In the scope of the International Polar Year 2007/2008, marine sediment cores were retrieved with RV Polarstern offshore the Prydz Bay to gain insight into land-ocean linkages of East Antarctic Ice Sheet (EAIS) dynamics, sea-ice formation, and regional palaeooceanography during the late Cenozoic. The scientific conception is based on the reconstruction of glaciomarine processes, comprising variations in ice-rafting, ice-shelf dynamics, and coastal bottom-water productivity. From our oldest sediment record, reaching back to 4.0 Ma, the results suggest a persistent presence of the EAIS in the Prydz Bay area during that time. The strongest glacial influence in the adjacent ocean appeared around the Plio-/Pleistocene boundary and during the mid-Pleistocene, consistent with maximum glaciation in the hinterland. The EAIS also fluctuated at glacial-interglacial timescales, documented by repeated stages of sediment reworking along the continental slope, prior to interglacials. The most apparent glacial retreat during the late Pleistocene took place after climate termination II, some 130 kyr ago. Another postglacial retreat event is evident from the inner shelf and commenced around 12 ka BP in agreement with ice shrinkage in adjacent onshore regions and global sea-level rise towards the Holocene. The variability of bottom-water formation in coastal polynyas reveals strong affinities to climate change that controls sea-ice extension. Strongest bottom-water activity apparently is related to intermediate interglacial stages, while it diminishes during both glacial stages and peak warmth. During glacial stages the permanent presence of near-shore sea-ice prevents the formation of polynyas, while during very warm stages the seasonal waxing and waning of sea ice is reduced and retards the brine-release effect needed for dense-water formation. The latter phenomenon in conjunction with glacial retreat was well expressed during climate termination II, which is also documented as an exceptionally warm event in Antarctic ice cores.

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