Physical Conditions of Fast Glacier Flow: 2. Variable Extent of Anisotropic Ice and Soft Basal Sediment From Seismic Reflection Data Acquired on Store Glacier, West Greenland
Source at https://doi.org/10.1002/2017JF004297 . Outlet glaciers of the Greenland Ice Sheet transport ice from the interior to the ocean and contribute directly to sea level rise because discharge and ablation often exceed the accumulation. To develop a better understanding of these fast‐flowing gla...
Published in: | Journal of Geophysical Research: Earth Surface |
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American Geophysical Union (AGU)
2018
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Online Access: | https://hdl.handle.net/10037/13525 https://doi.org/10.1002/2017JF004297 |
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ftunivtroemsoe:oai:munin.uit.no:10037/13525 2023-05-15T14:27:45+02:00 Physical Conditions of Fast Glacier Flow: 2. Variable Extent of Anisotropic Ice and Soft Basal Sediment From Seismic Reflection Data Acquired on Store Glacier, West Greenland Hofstede, C. Christoffersen, P. Hubbard, B. Doyle, S.H. Young, T.J. Diez, A. Eisen, O. Hubbard, Alun Lloyd 2018-01-09 https://hdl.handle.net/10037/13525 https://doi.org/10.1002/2017JF004297 eng eng American Geophysical Union (AGU) Journal of Geophysical Research - Earth Surface info:eu-repo/grantAgreement/RCN/SFF/223259/Norway/Centre for Arctic Gas Hydrate, Environment and Climate/CAGE/ Hofstede, C., Christoffersen, P., Hubbard, B., Doyle, S.H., Young, T., Diez, A., . Hubbard, A.L. (2018). Physical Conditions of Fast Glacier Flow: 2. Variable Extent of Anisotropic Ice and Soft Basal Sediment From Seismic Reflection Data Acquired on Store Glacier, West Greenland. Journal of Geophysical Research - Earth Surface, 123(2), 349-362. https://doi.org/10.1002/2017JF004297 FRIDAID 1570392 doi:10.1002/2017JF004297 2169-9003 2169-9011 https://hdl.handle.net/10037/13525 openAccess VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Kvartærgeologi glasiologi: 465 VDP::Mathematics and natural science: 400::Geosciences: 450::Quaternary geology glaciology: 465 subglacial sliding deformation anisotropy patches seismic Journal article Tidsskriftartikkel Peer reviewed 2018 ftunivtroemsoe https://doi.org/10.1002/2017JF004297 2021-06-25T17:55:53Z Source at https://doi.org/10.1002/2017JF004297 . Outlet glaciers of the Greenland Ice Sheet transport ice from the interior to the ocean and contribute directly to sea level rise because discharge and ablation often exceed the accumulation. To develop a better understanding of these fast‐flowing glaciers, we investigate the basal conditions of Store Glacier, a large outlet glacier flowing into Uummannaq Fjord in west Greenland. We use two crossing seismic profiles acquired near the centerline, 30 km upstream of the calving front, to interpret the physical nature of the ice and bed. We identify one notably englacial and two notably subglacial seismic reflections on both profiles. The englacial reflection represents a change in crystal orientation fabric, interpreted to be the Holocene‐Wisconsin transition. From Amplitude‐Versus‐Angle (AVA) analysis we infer that the deepest ∼80 m of ice of the parallel‐flow profile below this reflection is anisotropic with an enhancement of simple shear of ∼2. The ice is underlain by ∼45 m of unconsolidated sediments, below which there is a strong reflection caused by the transition to consolidated sediments. In the across‐flow profile subglacial properties vary over small scale and the polarity of the ice‐bed reflection switches from positive to negative. We interpret these as patches of different basal slipperiness associated with variable amounts of water. Our results illustrate variability in basal properties, and hence ice‐bed coupling, at a spatial scale of ∼100 m, highlighting the need for direct observations of the bed to improve the basal boundary conditions in ice‐dynamic models. Article in Journal/Newspaper Arctic glacier Greenland Ice Sheet Uummannaq University of Tromsø: Munin Open Research Archive Greenland Uummannaq Fjord ENVELOPE(-52.968,-52.968,70.925,70.925) Journal of Geophysical Research: Earth Surface 123 2 349 362 |
institution |
Open Polar |
collection |
University of Tromsø: Munin Open Research Archive |
op_collection_id |
ftunivtroemsoe |
language |
English |
topic |
VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Kvartærgeologi glasiologi: 465 VDP::Mathematics and natural science: 400::Geosciences: 450::Quaternary geology glaciology: 465 subglacial sliding deformation anisotropy patches seismic |
spellingShingle |
VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Kvartærgeologi glasiologi: 465 VDP::Mathematics and natural science: 400::Geosciences: 450::Quaternary geology glaciology: 465 subglacial sliding deformation anisotropy patches seismic Hofstede, C. Christoffersen, P. Hubbard, B. Doyle, S.H. Young, T.J. Diez, A. Eisen, O. Hubbard, Alun Lloyd Physical Conditions of Fast Glacier Flow: 2. Variable Extent of Anisotropic Ice and Soft Basal Sediment From Seismic Reflection Data Acquired on Store Glacier, West Greenland |
topic_facet |
VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Kvartærgeologi glasiologi: 465 VDP::Mathematics and natural science: 400::Geosciences: 450::Quaternary geology glaciology: 465 subglacial sliding deformation anisotropy patches seismic |
description |
Source at https://doi.org/10.1002/2017JF004297 . Outlet glaciers of the Greenland Ice Sheet transport ice from the interior to the ocean and contribute directly to sea level rise because discharge and ablation often exceed the accumulation. To develop a better understanding of these fast‐flowing glaciers, we investigate the basal conditions of Store Glacier, a large outlet glacier flowing into Uummannaq Fjord in west Greenland. We use two crossing seismic profiles acquired near the centerline, 30 km upstream of the calving front, to interpret the physical nature of the ice and bed. We identify one notably englacial and two notably subglacial seismic reflections on both profiles. The englacial reflection represents a change in crystal orientation fabric, interpreted to be the Holocene‐Wisconsin transition. From Amplitude‐Versus‐Angle (AVA) analysis we infer that the deepest ∼80 m of ice of the parallel‐flow profile below this reflection is anisotropic with an enhancement of simple shear of ∼2. The ice is underlain by ∼45 m of unconsolidated sediments, below which there is a strong reflection caused by the transition to consolidated sediments. In the across‐flow profile subglacial properties vary over small scale and the polarity of the ice‐bed reflection switches from positive to negative. We interpret these as patches of different basal slipperiness associated with variable amounts of water. Our results illustrate variability in basal properties, and hence ice‐bed coupling, at a spatial scale of ∼100 m, highlighting the need for direct observations of the bed to improve the basal boundary conditions in ice‐dynamic models. |
format |
Article in Journal/Newspaper |
author |
Hofstede, C. Christoffersen, P. Hubbard, B. Doyle, S.H. Young, T.J. Diez, A. Eisen, O. Hubbard, Alun Lloyd |
author_facet |
Hofstede, C. Christoffersen, P. Hubbard, B. Doyle, S.H. Young, T.J. Diez, A. Eisen, O. Hubbard, Alun Lloyd |
author_sort |
Hofstede, C. |
title |
Physical Conditions of Fast Glacier Flow: 2. Variable Extent of Anisotropic Ice and Soft Basal Sediment From Seismic Reflection Data Acquired on Store Glacier, West Greenland |
title_short |
Physical Conditions of Fast Glacier Flow: 2. Variable Extent of Anisotropic Ice and Soft Basal Sediment From Seismic Reflection Data Acquired on Store Glacier, West Greenland |
title_full |
Physical Conditions of Fast Glacier Flow: 2. Variable Extent of Anisotropic Ice and Soft Basal Sediment From Seismic Reflection Data Acquired on Store Glacier, West Greenland |
title_fullStr |
Physical Conditions of Fast Glacier Flow: 2. Variable Extent of Anisotropic Ice and Soft Basal Sediment From Seismic Reflection Data Acquired on Store Glacier, West Greenland |
title_full_unstemmed |
Physical Conditions of Fast Glacier Flow: 2. Variable Extent of Anisotropic Ice and Soft Basal Sediment From Seismic Reflection Data Acquired on Store Glacier, West Greenland |
title_sort |
physical conditions of fast glacier flow: 2. variable extent of anisotropic ice and soft basal sediment from seismic reflection data acquired on store glacier, west greenland |
publisher |
American Geophysical Union (AGU) |
publishDate |
2018 |
url |
https://hdl.handle.net/10037/13525 https://doi.org/10.1002/2017JF004297 |
long_lat |
ENVELOPE(-52.968,-52.968,70.925,70.925) |
geographic |
Greenland Uummannaq Fjord |
geographic_facet |
Greenland Uummannaq Fjord |
genre |
Arctic glacier Greenland Ice Sheet Uummannaq |
genre_facet |
Arctic glacier Greenland Ice Sheet Uummannaq |
op_relation |
Journal of Geophysical Research - Earth Surface info:eu-repo/grantAgreement/RCN/SFF/223259/Norway/Centre for Arctic Gas Hydrate, Environment and Climate/CAGE/ Hofstede, C., Christoffersen, P., Hubbard, B., Doyle, S.H., Young, T., Diez, A., . Hubbard, A.L. (2018). Physical Conditions of Fast Glacier Flow: 2. Variable Extent of Anisotropic Ice and Soft Basal Sediment From Seismic Reflection Data Acquired on Store Glacier, West Greenland. Journal of Geophysical Research - Earth Surface, 123(2), 349-362. https://doi.org/10.1002/2017JF004297 FRIDAID 1570392 doi:10.1002/2017JF004297 2169-9003 2169-9011 https://hdl.handle.net/10037/13525 |
op_rights |
openAccess |
op_doi |
https://doi.org/10.1002/2017JF004297 |
container_title |
Journal of Geophysical Research: Earth Surface |
container_volume |
123 |
container_issue |
2 |
container_start_page |
349 |
op_container_end_page |
362 |
_version_ |
1766301651209027584 |