Radar derived subglacial properties and landforms beneath Rutford Ice Stream, West Antarctica

Schlegel, Rebecca; Murray, Tavi; Smith, Andrew M. ORCID: https://orcid.org/0000-0001-8577-482X; Brisbourne, Alex M. ORCID: https://orcid.org/0000-0002-9887-7120; Booth, Adam D.; King, Edward C. ORCID: https://orcid.org/0000-0003-3793-3915; Clark, Roger A.. 2022 Radar derived subglacial properties and landforms beneath Rutford Ice Stream, West Antarctica. Journal of Geophysical Research: Earth Surface, 127 (1), e2021JF006349. 18, pp. 10.1029/2021JF006349

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Abstract/Summary

Basal properties beneath ice streams and glaciers are known to be a control for ice flow dynamics, hence knowledge of them is crucial for predicting sea level due to changes in glacial dynamics. Basal properties, processes and topography also drive the formation of subglacial landforms. Bed properties beneath Rutford Ice Stream (West Antarctica) have previously been described using seismic acoustic impedance measurements at a sparse spatial coverage. Here, we derive bed properties in a 15 x 17 km grid of surface radar data with coverage and sampling much higher than previous seismic studies. Bed reflection amplitudes in surface radar data were calibrated using sediment porosities (ranging from 0.4 – 0.5) derived from seismic acoustic impedance. We find the bed properties are spatially variable, consisting of low porosity material in some areas and soft sediment in other areas. Comparison of seismic and surface radar data imply the low porosity material to be a consolidated sediment or sedimentary rock. Mega-scale glacial lineations (MSGLs) are ubiquitous on the bed and consist of soft, high porosity, probably deforming sediment, consistent with previous interpretations of MSGLs. We find some MSGLs have high reflectivity on their crest, interpreted as water bodies overlying high porosity sediment, whereas the trough around and the upstream end of some landforms consist of low porosity material. Integrating these different observations, we place constraints on possible explanations for the occurrence of water on the crest of landforms.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1029/2021JF006349
ISSN:	2169-9011
Additional Keywords:	Ice stream, Bed properties, Radar Reflectivity, West Antarctica
Date made live:	04 Jan 2022 12:26 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/529402

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