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Summit of the East Antarctic Ice Sheet underlain by thick ice-crystal fabric layers linked to glacial-interglacial environmental change

Wang, Bangbing; Sun, Bo; Martin, Carlos; Ferraccioli, Fausto; Steinhage, Daniel; Cui, Xiangbin; Siegert, Martin. 2017 Summit of the East Antarctic Ice Sheet underlain by thick ice-crystal fabric layers linked to glacial-interglacial environmental change. In: Siegert, M.J.; Jamieson, S.S.R.; White, D.A., (eds.) Exploration of subsurface Antarctica: uncovering past changes and modern processes. London, Geological Society of London. (Geological Society of London, special publication, 461).

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Abstract/Summary

Ice cores in Antarctica and Greenland reveal ice-crystal fabrics that can be softer under simple shear compared with isotropic ice. Owing to the sparseness of ice cores in regions away from the ice divide, we currently lack information about the spatial distribution of ice fabrics and its association with ice flow. Radio-wave reflections are influenced by ice-crystal alignments, allowing them to be tracked provided reflections are recorded simultaneously in orthogonal orientations (polarimetric measurements). Here, we image spatial variations in the thickness and extent of ice fabric across Dome A in East Antarctica, by interpreting polarimetric radar data. We identify four prominent fabric units, each several hundred metres thick, extending over hundreds of square kilometres. By tracing internal ice-sheet layering to the Vostok ice core, we are able to determine the approximate depth–age profile at Dome A. The fabric units correlate with glacial–interglacial cycles, most noticeably revealing crystal alignment contrasts between the Eemian and the glacial episodes before and after. The anisotropy within these fabric layers has a spatial pattern determined by ice flow over subglacial topography.

Item Type: Publication - Book Section
Digital Object Identifier (DOI): 10.1144/SP461.1
Programmes: BAS Programmes > BAS Programmes 2015 > Geology and Geophysics
BAS Programmes > BAS Programmes 2015 > Ice Dynamics and Palaeoclimate
ISSN: 20411723
Date made live: 30 May 2017 14:04 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/511393

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