Bed-type variability and till (dis)continuity beneath Thwaites Glacier, West Antarctica
Abstract Recent seismic measurements from upper Thwaites Glacier indicate that the bed-type variability is closely related to the along-flow basal topography. In high-relief subglacial highlands, stoss sides of topographic highs have a relatively higher acoustic impedance (‘hard’ bed) with lower aco...
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crcambridgeupr:10.1017/aog.2019.32 2024-09-30T14:22:46+00:00 Bed-type variability and till (dis)continuity beneath Thwaites Glacier, West Antarctica Muto, Atsuhiro Alley, Richard B. Parizek, Byron R. Anandakrishnan, Sridhar 2019 http://dx.doi.org/10.1017/aog.2019.32 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0260305519000326 en eng Cambridge University Press (CUP) http://creativecommons.org/licenses/by/4.0/ Annals of Glaciology volume 60, issue 80, page 82-90 ISSN 0260-3055 1727-5644 journal-article 2019 crcambridgeupr https://doi.org/10.1017/aog.2019.32 2024-09-04T04:03:43Z Abstract Recent seismic measurements from upper Thwaites Glacier indicate that the bed-type variability is closely related to the along-flow basal topography. In high-relief subglacial highlands, stoss sides of topographic highs have a relatively higher acoustic impedance (‘hard’ bed) with lower acoustic impedance (‘soft’ till) on lee sides. This pattern is similar to observations of many deglaciated terrains. Subglacial hydraulic-potential gradient and its divergence show a tendency for water to diverge over the stoss sides and converge into the lee sides. Convergence favors a thicker or more widespread water system, which can more efficiently decouple ice from the underlying till. Under such circumstances, till deformation does occur but, fluxes are relatively small. Till carried from the lee sides onto stoss sides of downstream bumps should couple to the ice more efficiently, increasing the ability for transport by till deformation. In turn, this suggests that steady-state till transport can be achieved if the stoss-side till layer is thin or discontinuous. In addition, the large basal shear stress generated in the highlands seems too high for a bed lubricated by a continuous although thin deforming till, suggesting till discontinuity, which would allow debris-laden ice to erode bedrock on stoss sides, supplying additional till for transport. Article in Journal/Newspaper Annals of Glaciology Antarc* Antarctica Thwaites Glacier West Antarctica Cambridge University Press Thwaites Glacier ENVELOPE(-106.750,-106.750,-75.500,-75.500) West Antarctica Annals of Glaciology 60 80 82 90 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
Abstract Recent seismic measurements from upper Thwaites Glacier indicate that the bed-type variability is closely related to the along-flow basal topography. In high-relief subglacial highlands, stoss sides of topographic highs have a relatively higher acoustic impedance (‘hard’ bed) with lower acoustic impedance (‘soft’ till) on lee sides. This pattern is similar to observations of many deglaciated terrains. Subglacial hydraulic-potential gradient and its divergence show a tendency for water to diverge over the stoss sides and converge into the lee sides. Convergence favors a thicker or more widespread water system, which can more efficiently decouple ice from the underlying till. Under such circumstances, till deformation does occur but, fluxes are relatively small. Till carried from the lee sides onto stoss sides of downstream bumps should couple to the ice more efficiently, increasing the ability for transport by till deformation. In turn, this suggests that steady-state till transport can be achieved if the stoss-side till layer is thin or discontinuous. In addition, the large basal shear stress generated in the highlands seems too high for a bed lubricated by a continuous although thin deforming till, suggesting till discontinuity, which would allow debris-laden ice to erode bedrock on stoss sides, supplying additional till for transport. |
format |
Article in Journal/Newspaper |
author |
Muto, Atsuhiro Alley, Richard B. Parizek, Byron R. Anandakrishnan, Sridhar |
spellingShingle |
Muto, Atsuhiro Alley, Richard B. Parizek, Byron R. Anandakrishnan, Sridhar Bed-type variability and till (dis)continuity beneath Thwaites Glacier, West Antarctica |
author_facet |
Muto, Atsuhiro Alley, Richard B. Parizek, Byron R. Anandakrishnan, Sridhar |
author_sort |
Muto, Atsuhiro |
title |
Bed-type variability and till (dis)continuity beneath Thwaites Glacier, West Antarctica |
title_short |
Bed-type variability and till (dis)continuity beneath Thwaites Glacier, West Antarctica |
title_full |
Bed-type variability and till (dis)continuity beneath Thwaites Glacier, West Antarctica |
title_fullStr |
Bed-type variability and till (dis)continuity beneath Thwaites Glacier, West Antarctica |
title_full_unstemmed |
Bed-type variability and till (dis)continuity beneath Thwaites Glacier, West Antarctica |
title_sort |
bed-type variability and till (dis)continuity beneath thwaites glacier, west antarctica |
publisher |
Cambridge University Press (CUP) |
publishDate |
2019 |
url |
http://dx.doi.org/10.1017/aog.2019.32 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0260305519000326 |
long_lat |
ENVELOPE(-106.750,-106.750,-75.500,-75.500) |
geographic |
Thwaites Glacier West Antarctica |
geographic_facet |
Thwaites Glacier West Antarctica |
genre |
Annals of Glaciology Antarc* Antarctica Thwaites Glacier West Antarctica |
genre_facet |
Annals of Glaciology Antarc* Antarctica Thwaites Glacier West Antarctica |
op_source |
Annals of Glaciology volume 60, issue 80, page 82-90 ISSN 0260-3055 1727-5644 |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1017/aog.2019.32 |
container_title |
Annals of Glaciology |
container_volume |
60 |
container_issue |
80 |
container_start_page |
82 |
op_container_end_page |
90 |
_version_ |
1811635463188905984 |