Antarctic Peninsula Ice Sheet evolution during the Cenozoic Era

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Type Article
Original languageEnglish
Pages (from-to)30-66
JournalQuaternary Science Reviews
Volume31
DOI
Publication statusPublished - 12 Jan 2012
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Abstract

Antarctic Peninsula Ice Sheet evolution during the Cenozoic Era The Antarctic Peninsula region is currently undergoing rapid environmental change, resulting in the thinning, acceleration and recession of glaciers and the sequential collapse of ice shelves. It is important to view these changes in the context of long-term palaeoenvironmental complexity and change and to understand the key processes controlling ice sheet growth and recession. In addition, numerical ice sheet models require detailed geological data for tuning and testing. Therefore, this paper systematically and holistically reviews all the published geological evidence for Antarctic Peninsula Ice Sheet variability for each key locality throughout the Cenozoic, and brings together the prevailing consensus of the extent, character and behaviour of the glaciations of the Antarctic Peninsula region. Major contributions include a downloadable database of 186 terrestrial and marine calibrated dates; an original reconstruction of the LGM ice sheet; and a new series of isochrones detailing ice sheet retreat following the LGM. This analysis shows that glaciation of Antarctica was initiated during the Early Cenozoic. Palaeogene records of Antarctic Peninsula glaciation are primarily restricted to King George Island, where glacigenic sediments document continental-wide glaciations, but with modification by local South Shetland Island ice caps. Evidence for Neogene glaciation is derived primarily from King George Island and James Ross Island, where glaciovolcanic strata indicate that ice thicknesses reached 500 to 850 m during glacials. This suggests that at this time the Antarctic Peninsula Ice Sheet draped, rather than drowned, the topography. Marine geophysical investigations indicate multiple ice sheet advances during this time. Seismic profiling of continental shelf-slope deposits indicates up to 10 large advances of the Antarctic Peninsula Ice Sheet during the Early Pleistocene, when the ice sheet was dominated by 40 kyr cycles. Glacials became more pronounced, reaching the continental shelf edge, and of longer duration during the Middle Pleistocene. During the Late Pleistocene, repeated glacials reached the shelf-edge, but ice shelves inhibited iceberg rafting. The Last Glacial Maximum (LGM) occurred at 18 ka BP, after which transitional glaciomarine sediments on the continental shelf indicate ice-sheet retreat. The continental shelf contains large bathymetric troughs, which were repeatedly occupied by large ice streams during Pleistocene glaciations. Retreat after the LGM was episodic in the Weddell Sea, with multiple re-advances and changes in ice-flow direction, but rapid in the Bellingshausen Sea. The Late Holocene epoch was characterised by repeated fluctuations in palaeoenvironmental conditions, with associated glacial readvances. However, this has been subsumed by rapid warming and ice-shelf collapse during the twentieth century.

Keywords

  • Antarctic Peninsula, Glaciation, Neogene, Palaeogene, quaternary, Last Glacial Maximum