Formation of ice-shelf moraines by accretion of sea water an

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TitleFormation of ice-shelf moraines by accretion of sea water and marine sediment at the southern margin of the McMurdo ice shelf, AntarcticaAbstractA combination of ground-penetrating radar surveys, physical sedimentology and ice composition measurements has been used to characterize ice and sediment accreted to the southern margin of the McMurdo Ice Shelf, Antarctica. The radar data and surface observations show that the iceshelf margin consists of strongly layered debris-rich ice that contains marine sediment and fossils. A modified Rayleigh-based distillation system has been used to model the isotopic fractionation from sea water to ice in a closed system. The model of ice formation is consistent with formation during almost complete freezing of a sea-water reservoir. By contrast, ice on the upstream side of the grounding line has formed during the early stages of freezing in which a small fraction of the sea-water reservoir has frozen. The model results and the presence of delicate, well-preserved marine fossils are interpreted as evidence of anchor ice formation on the seabed, and rafting of glaciomarine sediment into the bottom of the ice shelf. We argue that repeated accretion of sea water and marine sediment has produced a stacked sequence of ice and glaciomarine debris that forms shore-parallel ice-cored moraines. Copyright 2012 Publishing Technology.AcknowledgementsFieldwork was financially supported by a University of Otago research grant to G.W. and S.F., and laboratory analyses by a research grant to S.F. We thank Emma Davis for field assistance with the GPR survey, and Antarctica New Zealand for excellent logistical support. The comments of two anonymous referees resulted in considerable improvement of the manuscript.

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1st AuthorFitzsimons, S.AuthorFitzsimons, S.Mager, S.Frew, R.Clifford, A.Wilson, G.Year2012JournalAnnals of GlaciologyVolume53Number60Pages211-220DOI10.3189/2012AoG60A155URLhttps://www.scopus.com/inward/recor.....8e891ceca6b0e02142e22ab2cKeywordsaccretionglaciomarine depositground penetrating radarice marginice shelfisotopic fractionationmarine sedimentmoraineseawatersedimentology, AntarcticaEast AntarcticaMcMurdo Ice Shelf, rank5

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TypeArticleCitationFitzsimons, S., Mager, S., Frew, R., Clifford, A. and Wilson, G. (2012). Formation of ice-shelf moraines by accretion of sea water and marine sediment at the southern margin of the McMurdo ice shelf, Antarctica. Annals of Glaciology, 53(60): 211-220 IdentifierFitzsimons2012Relevancerank5

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Wilson, G.