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Radar derived Subglacial Properties and Landforms beneath Rutford Ice Stream, West Antarctica
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  • Rebecca Schlegel,
  • Tavi Murray,
  • Andrew Mark Smith,
  • Alex Mark Brisbourne,
  • Adam D Booth,
  • Edward Charles King,
  • Roger Arthur Clark
Rebecca Schlegel
Swansea University, Swansea University

Corresponding Author:[email protected]

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Tavi Murray
Swansea University, Swansea University
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Andrew Mark Smith
British Antarctic Survey, British Antarctic Survey
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Alex Mark Brisbourne
British Antarctic Survey, British Antarctic Survey
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Adam D Booth
University of Leeds, University of Leeds
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Edward Charles King
British Antarctic Survey, British Antarctic Survey
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Roger Arthur Clark
University of Leeds, University of Leeds
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Abstract

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.
Jan 2022Published in Journal of Geophysical Research: Earth Surface volume 127 issue 1. 10.1029/2021JF006349