Subglacial processes on an Antarctic ice stream bed. 1: Sediment transport and bedform genesis inferred from marine geophysical data

Stephen J. Livingstone*, Chris R. Stokes, Colm Ó Cofaigh, Claus-Dieter Hillenbrand, Andreas Vieli, Stewart S. R. Jamieson, Matteo Spagnolo, Julian A. Dowdeswell

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)
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Abstract

The spatial pattern and morphometry of bedforms and their relationship to sediment thickness have been analysed in the Marguerite Bay Palaeo-ice stream Trough, western Antarctic Peninsula. Over 17 000 glacial landforms were measured from geophysical datasets, and sediment thickness maps were generated from acoustic sub-bottom profiler data. These analyses reveal a complex bedform pattern characterised by considerable spatial diversity, influenced heavily by the underlying substrate. The variability in length and density of mega-scale lineations indicates an evolving bedform signature, whereby landforms are preserved at different stages of maturity. Lineation generation and attenuation is associated with regions of thick, soft till where deformation was likely to be the greatest. The distribution of soft till and the localised extent of grounding-zone wedges (GZWs) indicate a dynamic sedimentary system characterised by considerable spatio-temporal variability in sediment erosion, transport and deposition. Formation of GZWs on the outer shelf of Marguerite Trough, within the error range of the radiocarbon dates, requires large sediment fluxes (upwards of 1000 m(3) a(-1) (m grounding line width)(-1)), and a >1 m thick mobile till layer, or rapid basal sliding velocities (upwards of 6 km a(-1)).

Original languageEnglish
Pages (from-to)270-284
Number of pages15
JournalJournal of Glaciology
Volume62
Issue number232
Early online date17 Mar 2016
DOIs
Publication statusPublished - Apr 2016

Keywords

  • glacial lineations
  • grounding-zone wedges
  • ice stream
  • mega-scale
  • subglacial bedforms
  • till

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