Ross Sea paleo-ice sheet drainage and deglacial history duri

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TitleRoss Sea paleo-ice sheet drainage and deglacial history during and since the LGMAbstractOnshore and offshore studies show that an expanded, grounded ice sheet occupied the Ross Sea Embayment during the Last Glacial Maximum (LGM). Results from studies of till provenance and the orientation of geomorphic features on the continental shelf show that more than half of the grounded ice sheet consisted of East Antarctic ice flowing through Transantarctic Mountain (TAM) outlet glaciers; the remainder came from West Antarctica. Terrestrial data indicate little or no thickening in the upper catchment regions in both West and East Antarctica during the LGM. In contrast, evidence from the mouths of the southern and central TAM outlet glaciers indicate surface elevations between 1000m and 1100m (above present-day sea level). Farther north along the western margin of the Ross Ice Sheet, surface elevations reached 720m on Ross Island, and 400m at Terra Nova Bay. Evidence from Marie Byrd Land at the eastern margin of the ice sheet indicates that the elevation near the present-day grounding line was more than 800masl, while at Siple Dome in the central Ross Embayment, the surface elevation was about 950masl. Farther north, evidence that the ice sheet was grounded on the middle and the outer continental shelf during the LGM implies that surface elevations had to be at least 100m above the LGM sea level. The apparent low surface profile and implied low basal shear stress in the central and eastern embayment suggests that although the ice streams may have slowed during the LGM, they remained active. Ice-sheet retreat from the western Ross Embayment during the Holocene is constrained by marine and terrestrial data. Ages from marine sediments suggest that the grounding line had retreated from its LGM outer shelf location only a few tens of kilometer to a location south of Coulman Island by Â 13ka BP. The ice sheet margin was located in the vicinity of the Drygalski Ice Tongue by Â 11ka BP, just north of Ross Island by Â 7.8ka BP, and near Hatherton Glacier by Â 6.8ka BP. Farther south, 10Be exposure ages from glacial erratics on nunataks near the mouths of Reedy, Scott and Beardmore Glaciers indicate thinning during the mid to late Holocene, but the grounding line did not reach its present position until 2 to 3ka BP. Marine dates, which are almost exclusively Acid Insoluble Organic (AIO) dates, are consistently older than those derived from terrestrial data. However, even these ages indicate that the ice sheet experienced significant retreat after Â 13ka BP. Geomorphic features indicate that during the final stages of ice sheet retreat ice flowing through the TAM remained grounded on the shallow western margin of Ross Sea. The timing of retreat from the central Ross Sea remains unresolved; the simplest reconstruction is to assume that the grounding line here started to retreat from the continental shelf more or less in step with the retreat from the western and eastern sectors. An alternative hypothesis, which relies on the validity of radiocarbon ages from marine sediments, is that grounded ice had retreated from the outer continental shelf prior to the LGM. More reliable ages from marine sediments in the central Ross Embayment are needed to test and validate this hypothesis. â"' 2014 The Authors.AcknowledgementsWe thank all of the many colleagues and students, past and present, who have worked with us on the glacial history of the Ross Sea region. The Office of Polar Programs of the National Science Foundation funded the US component of this work. The Swedish component was funded by the Swedish Polar Research Secretariat, Swedish Research Council and the New Zealand component by the New Zealand Foundation for Research Science and Technology

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1st AuthorAnderson, J.AuthorAnderson, J.Conway, H.Bart, P.Witus, A.Greenwood, S.McKay, R.Hall, B.Ackert, R.Licht, K.Jakobsson, M.Stone, J.Year2014JournalQuaternary Science ReviewsVolume100Pages31-54DOI10.1016/j.quascirev.2013.08.020URLhttps://www.scopus.com/inward/recor.....8d4cc7689eef240a042fb04d7KeywordsCatchmentsGlacial geologyGlaciersLandformsSea levelSedimentsSubmarine geology, Alternative hypothesisGlacial historyLast Glacial MaximumLGM-post LGMMid to late HoloceneOuter continental shelvesPaleodrainageRoss Sea, Ice, continental shelfdeglaciationdrainagegeomorphologyglacial historygrounding lineice retreatice sheetLast Glacial Maximummarine sedimenttill, AntarcticaRoss SeaSouthern Ocean, rank3Author KeywordsGlacial historyLGM-post LGMPaleodrainageRoss Sea

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TypeArticleCitationAnderson, J., Conway, H., Bart, P., Witus, A., Greenwood, S., McKay, R., Hall, B., Ackert, R., Licht, K., Jakobsson, M. and Stone, J. (2014). Ross Sea paleo-ice sheet drainage and deglacial history during and since the LGM. Quaternary Science Reviews, 100: 31-54 IdentifierAnderson2014Relevancerank3