Browsing by Author "Bentley, MJ"

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    A community-based geological reconstruction of Antarctic ice sheet deglaciation since the last glacial maximum
    (Elsevier, 2014-09-15) Bentley, MJ; O'Cofaigh, C; Anderson, JB; Conway, H; Davies, B; Graham, AGC; Hillenbrand, CD; Hodgson, DA; Jamieson, SSR; Larter, RD; Mackintosh, AN; Smith, JA; Verleyen, E; Ackert, RP; Bart, PJ; Berg, S; Brunstein, D; Canals, M; Colhoun, EA; Crosta, X; Dickens, WA; Domack, E; Dowdeswell, JA; Dunbar, R; Ehrmann, W; Evans, J; Favier, V; Fink, D; Fogwill, CJ; Glasser, NF; Gohl, K; Golledge, NR; Goodwin, I; Gore, DB; Greenwood, SL; Hall, BL; Hall, K; Hedding, DW; Hein, AS; Hocking, EP; Jakobsson, M; Johnson, JS; Jomelli, V; Jones, RS; Klages, JP; Kristoffersen, Y; Kuhn, G; Leventer, A; Licht, K; Lilly, K; Lindow, J; Livingstone, SJ; Massé, G; McGlone, MS; McKay, RM; Melles, M; Miura, H; Mulvaney, R; Nel, W; Nitsche, FO; O'Brien, PE; Post, AL; Roberts, SJ; Saunders, KM; Selkirk, PM; Simms, AR; Spiegel, C; Stolldorf, TD; Sugden, DE; van der Putten, N; van Ommen, TD; Verfaillie, D; Vyverman, W; Wagner, B; White, DA; Witus, AE; Zwartz, D
    A robust understanding of Antarctic Ice Sheet deglacial history since the Last Glacial Maximum is important in order to constrain ice sheet and glacial-isostatic adjustment models, and to explore the forcing mechanisms responsible for ice sheet retreat. Such understanding can be derived from a broad range of geological and glaciological datasets and recent decades have seen an upsurge in such data gathering around the continent and Sub-Antarctic islands. Here, we report a new synthesis of those datasets, based on an accompanying series of reviews of the geological data, organised by sector. We present a series of timeslice maps for 20 ka, 15 ka, 10 ka and 5 ka, including grounding line position and ice sheet thickness changes, along with a clear assessment of levels of confidence. The reconstruction shows that the Antarctic Ice sheet did not everywhere reach the continental shelf edge at its maximum, that initial retreat was asynchronous, and that the spatial pattern of deglaciation was highly variable, particularly on the inner shelf. The deglacial reconstruction is consistent with a moderate overall excess ice volume and with a relatively small Antarctic contribution to meltwater pulse 1a. We discuss key areas of uncertainty both around the continent and by time interval, and we highlight potential priorities for future work. The synthesis is intended to be a resource for the modelling and glacial geological community. © 2014 The Authors. CC BY license
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    Ellsworth Subglacial Lake, West Antarctica: a review of its history and recent field campaigns
    (John Wiley & Sons, Inc, 2011-01-01) Ross, N; Siegert, MJ; Rivera, A; Bentley, MJ; Blake, D; Capper, L; Clarke, R; Cockell, CS; Corr, HFJ; Harris, W; Hill, C; Hindmarsh, RCA; Hodgson, DA; King, EC; Lamb, H; Maher, B; Makinson, K; Mowlem, M; Parnell, J; Pearce, DA; Priscu, J; Smith, AM; Tait, A; Tranter, M; Wadham, JL; Whalley, WB; Woodward, JC
    Ellsworth Subglacial Lake, first observed in airborne radio echo sounding data acquired in 1978, is located within a long, deep subglacial trough within the Ellsworth Subglacial Highlands of West Antarctica. Geophysical surveys have characterized the lake, its subglacial catchment, and the thickness, structure, and flow of the overlying ice sheet. Covering 28.9 km2 , Ellsworth Subglacial Lake is located below 2.9 to 3.3 km of ice at depths of -1361 to -1030 m. Seismic reflection data have shown the lake to be up to 156 m deep and underlain by unconsolidated sediments. Ice sheet flow over the lake is characterized by low velocities (<6 m yr-1 ), flow convergence, and longitudinal extension. The lake appears to be in steady state, although the hydrological balance may vary over glacial-interglacial cycles. Direct access, measurement, and sampling of Ellsworth Subglacial Lake are planned for the 2012/2013 Antarctic field season. The aims of this access experiment are to determine (1) the presence, character, and maintenance of microbial life in Antarctic subglacial lakes and (2) the Quaternary history of the West Antarctic ice sheet. Geophysical data have been used to define a preferred lake access site. The factors that make this location suitable for exploration are (1) a relatively thin overlying ice column (~3.1 km), (2) a significant measured water depth (~143 m), (3) >2 m of sediment below the lake floor, (4) water circulation modeling suggesting a melting ice-water interface, and (5) coring that can target the deepest point of the lake floor away from marginal, localized sediment sources. © 2011 American Geophysical Union.