Pleistocene variability of Antarctic Ice Sheet extent in the

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TitlePleistocene variability of Antarctic Ice Sheet extent in the Ross EmbaymentAbstractCores acquired by the ANDRILL McMurdo Ice Shelf Project (AND-1B) provide the basis for a new sedimentation model for glacimarine depositional sequences that reflect cyclic glacial-interglacial fluctuations of a marine-based ice sheet in the western Ross Embayment over the past 2.0Ma. Notwithstanding periodic erosion during advances of the ice sheet, uncertainties inherent to the sedimentological interpretation, and a limited number of chronological datums, it is clear that subglacial to grounding-zone sedimentation was dominant at the AND-1B site during the Late Pleistocene with interglacials being represented only by thin intervals of ice-shelf sediment. Each sequence is characterised by subglacial, massive diamictite that pass upwards into glacimarine diamictites and mudstones. This provides the first direct evidence that the marine-based Antarctic Ice Sheet has oscillated between a grounded and floating state at least 7times in the Ross Embayment over the last 780ka, implying a Milankovitch orbital influence. An unconformity in AND-1B, that spans most (~200kyr) of the Mid-Pleistocene Transition is inferred to represent widespread expansion of a marine-based ice sheet in the Ross Embayment at 0.8Ma. Prior to 1.0Ma, interglacial periods are characterised by open-water conditions at the drill site with high abundances of volcanoclastic deposits and occasional diatomaceous sediments. These may have responded to precession (~20-kyr) or obliquity (~40-kyr) orbital control. The occurrence of 6.7m of phonolitic glass reworked from Mt Erebus in interglacial deposits beneath Last Glacial Maximum till requires open ocean or ice shelf conditions in the western Ross Sea around the drill site within the past 250ka and implies a Ross Ice Shelf similar to or less extensive than today during Marine Isotope Stage 7 or 5. © 2011 Elsevier Ltd.AcknowledgementsThe scientific studies for ANDRILL are jointly supported by the US National Science Foundation, the NZ Foundation for Research Science and Technology and the Royal Society of New Zealand Marsden Fund, the Italian Antarctic Research Programme, the German Research Foundation and the Alfred Wegener Institute for Polar and Marine Research. We thank Michael Hambrey and John Hiemstra for constructive reviews that helped significantly improve this paper.

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1st AuthorMcKay, R.AuthorMcKay, R.Naish, T.Powell, R.Barrett, P.Scherer, R.Talarico, F.Kyle, P.Monien, D.Kuhn, G.Jackolski, C.Williams, T.Year2012JournalQuaternary Science ReviewsVolume34Pages93-112DOI10.1016/j.quascirev.2011.12.012URLhttps://www.scopus.com/inward/recor.....5886304e4a613634c80cc7d77KeywordsDepositional sequencesDrill sitesFloating stateIce sheetIce shelvesInterglacial periodsInterglacialsLast Glacial MaximumLate PleistoceneMarine Isotope Stage 7MilankovitchOpen oceanOrbital controlPalaeoclimatologyPleistoceneRoss ice shelvesRoss SeaSedimentation modelSedimentological interpretationsSequence stratigraphyWest Antarctic Ice Sheet, Anoxic sedimentsClimatologyDepositsDrillsGlaciersIceIsotopesSedimentationStratigraphy, Glacial geology, diamictiteglacial-interglacial cycleice sheetice shelfLast Glacial Maximummarine isotope stagemudstonepaleoclimatePleistocenesediment coresedimentationsedimentologysequence stratigraphyvolcaniclastic deposit, AntarcticaEast AntarcticaMcMurdo Ice ShelfRoss EmbaymentWest Antarctica, rank3Author KeywordsPalaeoclimatologyPleistoceneSequence stratigraphyWest Antarctic Ice Sheet

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TypeArticleCitationMcKay, R., Naish, T., Powell, R., Barrett, P., Scherer, R., Talarico, F., Kyle, P., Monien, D., Kuhn, G., Jackolski, C. and Williams, T. (2012). Pleistocene variability of Antarctic Ice Sheet extent in the Ross Embayment. Quaternary Science Reviews, 34:93-112 doi:10.1016/j.quascirev.2011.12.012 IdentifierMcKay201293Relevancerank3

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Naish, T.