Evidence for a grounding line fan at the onset of a basal channel under the ice shelf of Support Force Glacier, Antarctica, revealed by reflection seismics
Curvilinear channels on the surface of an ice shelf indicate the presence of large channels at the base. Modelling studies have shown that where these surface expressions intersect the grounding line, they coincide with the likely outflow of subglacial water. An understanding of the initiation and t...
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ftcopernicus:oai:publications.copernicus.org:tc83933 2023-05-15T13:31:40+02:00 Evidence for a grounding line fan at the onset of a basal channel under the ice shelf of Support Force Glacier, Antarctica, revealed by reflection seismics Hofstede, Coen Beyer, Sebastian Corr, Hugh Eisen, Olaf Hattermann, Tore Helm, Veit Neckel, Niklas Smith, Emma C. Steinhage, Daniel Zeising, Ole Humbert, Angelika 2021-03-25 application/pdf https://doi.org/10.5194/tc-15-1517-2021 https://tc.copernicus.org/articles/15/1517/2021/ eng eng doi:10.5194/tc-15-1517-2021 https://tc.copernicus.org/articles/15/1517/2021/ eISSN: 1994-0424 Text 2021 ftcopernicus https://doi.org/10.5194/tc-15-1517-2021 2021-03-29T16:22:16Z Curvilinear channels on the surface of an ice shelf indicate the presence of large channels at the base. Modelling studies have shown that where these surface expressions intersect the grounding line, they coincide with the likely outflow of subglacial water. An understanding of the initiation and the ice–ocean evolution of the basal channels is required to understand the present behaviour and future dynamics of ice sheets and ice shelves. Here, we present focused active seismic and radar surveys of a basal channel, ∼950 m wide and ∼200 m high, and its upstream continuation beneath Support Force Glacier, which feeds into the Filchner Ice Shelf, West Antarctica. Immediately seaward from the grounding line, below the basal channel, the seismic profiles show an ∼6.75 km long, 3.2 km wide and 200 m thick sedimentary sequence with chaotic to weakly stratified reflections we interpret as a grounding line fan deposited by a subglacial drainage channel directly upstream of the basal channel. Further downstream the seabed has a different character; it consists of harder, stratified consolidated sediments, deposited under different glaciological circumstances, or possibly bedrock. In contrast to the standard perception of a rapid change in ice shelf thickness just downstream of the grounding line, we find a flat topography of the ice shelf base with an almost constant ice thickness gradient along-flow, indicating only little basal melting, but an initial widening of the basal channel, which we ascribe to melting along its flanks. Our findings provide a detailed view of a more complex interaction between the ocean and subglacial hydrology to form basal channels in ice shelves. Text Antarc* Antarctica Ice Shelf Ice Shelves Support Force Glacier West Antarctica Copernicus Publications: E-Journals Filchner Ice Shelf ENVELOPE(-40.000,-40.000,-79.000,-79.000) Support Force Glacier ENVELOPE(-47.500,-47.500,-83.083,-83.083) West Antarctica The Cryosphere 15 3 1517 1535 |
institution |
Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
Curvilinear channels on the surface of an ice shelf indicate the presence of large channels at the base. Modelling studies have shown that where these surface expressions intersect the grounding line, they coincide with the likely outflow of subglacial water. An understanding of the initiation and the ice–ocean evolution of the basal channels is required to understand the present behaviour and future dynamics of ice sheets and ice shelves. Here, we present focused active seismic and radar surveys of a basal channel, ∼950 m wide and ∼200 m high, and its upstream continuation beneath Support Force Glacier, which feeds into the Filchner Ice Shelf, West Antarctica. Immediately seaward from the grounding line, below the basal channel, the seismic profiles show an ∼6.75 km long, 3.2 km wide and 200 m thick sedimentary sequence with chaotic to weakly stratified reflections we interpret as a grounding line fan deposited by a subglacial drainage channel directly upstream of the basal channel. Further downstream the seabed has a different character; it consists of harder, stratified consolidated sediments, deposited under different glaciological circumstances, or possibly bedrock. In contrast to the standard perception of a rapid change in ice shelf thickness just downstream of the grounding line, we find a flat topography of the ice shelf base with an almost constant ice thickness gradient along-flow, indicating only little basal melting, but an initial widening of the basal channel, which we ascribe to melting along its flanks. Our findings provide a detailed view of a more complex interaction between the ocean and subglacial hydrology to form basal channels in ice shelves. |
format |
Text |
author |
Hofstede, Coen Beyer, Sebastian Corr, Hugh Eisen, Olaf Hattermann, Tore Helm, Veit Neckel, Niklas Smith, Emma C. Steinhage, Daniel Zeising, Ole Humbert, Angelika |
spellingShingle |
Hofstede, Coen Beyer, Sebastian Corr, Hugh Eisen, Olaf Hattermann, Tore Helm, Veit Neckel, Niklas Smith, Emma C. Steinhage, Daniel Zeising, Ole Humbert, Angelika Evidence for a grounding line fan at the onset of a basal channel under the ice shelf of Support Force Glacier, Antarctica, revealed by reflection seismics |
author_facet |
Hofstede, Coen Beyer, Sebastian Corr, Hugh Eisen, Olaf Hattermann, Tore Helm, Veit Neckel, Niklas Smith, Emma C. Steinhage, Daniel Zeising, Ole Humbert, Angelika |
author_sort |
Hofstede, Coen |
title |
Evidence for a grounding line fan at the onset of a basal channel under the ice shelf of Support Force Glacier, Antarctica, revealed by reflection seismics |
title_short |
Evidence for a grounding line fan at the onset of a basal channel under the ice shelf of Support Force Glacier, Antarctica, revealed by reflection seismics |
title_full |
Evidence for a grounding line fan at the onset of a basal channel under the ice shelf of Support Force Glacier, Antarctica, revealed by reflection seismics |
title_fullStr |
Evidence for a grounding line fan at the onset of a basal channel under the ice shelf of Support Force Glacier, Antarctica, revealed by reflection seismics |
title_full_unstemmed |
Evidence for a grounding line fan at the onset of a basal channel under the ice shelf of Support Force Glacier, Antarctica, revealed by reflection seismics |
title_sort |
evidence for a grounding line fan at the onset of a basal channel under the ice shelf of support force glacier, antarctica, revealed by reflection seismics |
publishDate |
2021 |
url |
https://doi.org/10.5194/tc-15-1517-2021 https://tc.copernicus.org/articles/15/1517/2021/ |
long_lat |
ENVELOPE(-40.000,-40.000,-79.000,-79.000) ENVELOPE(-47.500,-47.500,-83.083,-83.083) |
geographic |
Filchner Ice Shelf Support Force Glacier West Antarctica |
geographic_facet |
Filchner Ice Shelf Support Force Glacier West Antarctica |
genre |
Antarc* Antarctica Ice Shelf Ice Shelves Support Force Glacier West Antarctica |
genre_facet |
Antarc* Antarctica Ice Shelf Ice Shelves Support Force Glacier West Antarctica |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-15-1517-2021 https://tc.copernicus.org/articles/15/1517/2021/ |
op_doi |
https://doi.org/10.5194/tc-15-1517-2021 |
container_title |
The Cryosphere |
container_volume |
15 |
container_issue |
3 |
container_start_page |
1517 |
op_container_end_page |
1535 |
_version_ |
1766020072916123648 |