Geomorphology and shallow sub-sea-floor structures underneath the Ekström Ice Shelf, Antarctica

The Ekström Ice Shelf is one of numerous small ice shelves that fringe the coastline of western Dronning Maud Land, East Antarctica. Reconstructions of past ice-sheet extent in this area are poorly constrained, due to a lack of geomorphological evidence. Here, we present a compilation of geophysical...

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Published in:The Cryosphere
Main Authors: Oetting, Astrid, Smith, Emma C., Arndt, Jan Erik, Dorschel, Boris, Drews, Reinhard, Ehlers, Todd A., Gaedicke, Christoph, Hofstede, Coen, Klages, Johann P., Kuhn, Gerhard, Lambrecht, Astrid, Läufer, Andreas, Mayer, Christoph, Tiedemann, Ralf, Wilhelms, Frank, Eisen, Olaf
Format: Text
Language:English
Published: 2022
Subjects:
Online Access:https://doi.org/10.5194/tc-16-2051-2022
https://tc.copernicus.org/articles/16/2051/2022/
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spelling ftcopernicus:oai:publications.copernicus.org:tc98008 2023-05-15T14:02:18+02:00 Geomorphology and shallow sub-sea-floor structures underneath the Ekström Ice Shelf, Antarctica Oetting, Astrid Smith, Emma C. Arndt, Jan Erik Dorschel, Boris Drews, Reinhard Ehlers, Todd A. Gaedicke, Christoph Hofstede, Coen Klages, Johann P. Kuhn, Gerhard Lambrecht, Astrid Läufer, Andreas Mayer, Christoph Tiedemann, Ralf Wilhelms, Frank Eisen, Olaf 2022-05-30 application/pdf https://doi.org/10.5194/tc-16-2051-2022 https://tc.copernicus.org/articles/16/2051/2022/ eng eng doi:10.5194/tc-16-2051-2022 https://tc.copernicus.org/articles/16/2051/2022/ eISSN: 1994-0424 Text 2022 ftcopernicus https://doi.org/10.5194/tc-16-2051-2022 2022-06-06T16:22:44Z The Ekström Ice Shelf is one of numerous small ice shelves that fringe the coastline of western Dronning Maud Land, East Antarctica. Reconstructions of past ice-sheet extent in this area are poorly constrained, due to a lack of geomorphological evidence. Here, we present a compilation of geophysical surveys in front of and beneath the Ekström Ice Shelf, to identify and interpret evidence of past ice-sheet flow, extent and retreat. The sea floor beneath the Ekström Ice Shelf is dominated by an incised trough, which extends from the modern-day grounding line onto the continental shelf. Our surveys show that mega-scale glacial lineations cover most of the mouth of this trough, terminating 11 km away from the continental shelf break, indicating the most recent minimal extent of grounded ice in this region. Beneath the front ∼30 km of the ice shelf measured from the ice shelf edge towards the inland direction, the sea floor is characterised by an acoustically transparent sedimentary unit, up to 45 m thick. This is likely composed of subglacial till, further corroborating the presence of past grounded ice cover. Further inland, the sea floor becomes rougher, interpreted as a transition from subglacial tills to a crystalline bedrock, corresponding to the outcrop of the volcanic Explora Wedge at the sea floor. Ice retreat in this region appears to have happened rapidly in the centre of the incised trough, evidenced by a lack of overprinting of the lineations at the trough mouth. At the margins of the trough uniformly spaced recessional moraines suggest ice retreated more gradually. We estimate the palaeo-ice thickness at the calving front around the Last Glacial Maximum to have been at least 305 to 320 m, based on the depth of iceberg ploughmarks within the trough and sea level reconstructions. Given the similarity of the numerous small ice shelves along the Dronning Maud Land coast, these findings are likely representative for other ice shelves in this region and provide essential boundary conditions for palaeo ... Text Antarc* Antarctica Dronning Maud Land East Antarctica Ice Sheet Ice Shelf Ice Shelves Copernicus Publications: E-Journals Dronning Maud Land East Antarctica Ekström Ice Shelf ENVELOPE(-8.000,-8.000,-71.000,-71.000) The Cryosphere 16 5 2051 2066
institution Open Polar
collection Copernicus Publications: E-Journals
op_collection_id ftcopernicus
language English
description The Ekström Ice Shelf is one of numerous small ice shelves that fringe the coastline of western Dronning Maud Land, East Antarctica. Reconstructions of past ice-sheet extent in this area are poorly constrained, due to a lack of geomorphological evidence. Here, we present a compilation of geophysical surveys in front of and beneath the Ekström Ice Shelf, to identify and interpret evidence of past ice-sheet flow, extent and retreat. The sea floor beneath the Ekström Ice Shelf is dominated by an incised trough, which extends from the modern-day grounding line onto the continental shelf. Our surveys show that mega-scale glacial lineations cover most of the mouth of this trough, terminating 11 km away from the continental shelf break, indicating the most recent minimal extent of grounded ice in this region. Beneath the front ∼30 km of the ice shelf measured from the ice shelf edge towards the inland direction, the sea floor is characterised by an acoustically transparent sedimentary unit, up to 45 m thick. This is likely composed of subglacial till, further corroborating the presence of past grounded ice cover. Further inland, the sea floor becomes rougher, interpreted as a transition from subglacial tills to a crystalline bedrock, corresponding to the outcrop of the volcanic Explora Wedge at the sea floor. Ice retreat in this region appears to have happened rapidly in the centre of the incised trough, evidenced by a lack of overprinting of the lineations at the trough mouth. At the margins of the trough uniformly spaced recessional moraines suggest ice retreated more gradually. We estimate the palaeo-ice thickness at the calving front around the Last Glacial Maximum to have been at least 305 to 320 m, based on the depth of iceberg ploughmarks within the trough and sea level reconstructions. Given the similarity of the numerous small ice shelves along the Dronning Maud Land coast, these findings are likely representative for other ice shelves in this region and provide essential boundary conditions for palaeo ...
format Text
author Oetting, Astrid
Smith, Emma C.
Arndt, Jan Erik
Dorschel, Boris
Drews, Reinhard
Ehlers, Todd A.
Gaedicke, Christoph
Hofstede, Coen
Klages, Johann P.
Kuhn, Gerhard
Lambrecht, Astrid
Läufer, Andreas
Mayer, Christoph
Tiedemann, Ralf
Wilhelms, Frank
Eisen, Olaf
spellingShingle Oetting, Astrid
Smith, Emma C.
Arndt, Jan Erik
Dorschel, Boris
Drews, Reinhard
Ehlers, Todd A.
Gaedicke, Christoph
Hofstede, Coen
Klages, Johann P.
Kuhn, Gerhard
Lambrecht, Astrid
Läufer, Andreas
Mayer, Christoph
Tiedemann, Ralf
Wilhelms, Frank
Eisen, Olaf
Geomorphology and shallow sub-sea-floor structures underneath the Ekström Ice Shelf, Antarctica
author_facet Oetting, Astrid
Smith, Emma C.
Arndt, Jan Erik
Dorschel, Boris
Drews, Reinhard
Ehlers, Todd A.
Gaedicke, Christoph
Hofstede, Coen
Klages, Johann P.
Kuhn, Gerhard
Lambrecht, Astrid
Läufer, Andreas
Mayer, Christoph
Tiedemann, Ralf
Wilhelms, Frank
Eisen, Olaf
author_sort Oetting, Astrid
title Geomorphology and shallow sub-sea-floor structures underneath the Ekström Ice Shelf, Antarctica
title_short Geomorphology and shallow sub-sea-floor structures underneath the Ekström Ice Shelf, Antarctica
title_full Geomorphology and shallow sub-sea-floor structures underneath the Ekström Ice Shelf, Antarctica
title_fullStr Geomorphology and shallow sub-sea-floor structures underneath the Ekström Ice Shelf, Antarctica
title_full_unstemmed Geomorphology and shallow sub-sea-floor structures underneath the Ekström Ice Shelf, Antarctica
title_sort geomorphology and shallow sub-sea-floor structures underneath the ekström ice shelf, antarctica
publishDate 2022
url https://doi.org/10.5194/tc-16-2051-2022
https://tc.copernicus.org/articles/16/2051/2022/
long_lat ENVELOPE(-8.000,-8.000,-71.000,-71.000)
geographic Dronning Maud Land
East Antarctica
Ekström Ice Shelf
geographic_facet Dronning Maud Land
East Antarctica
Ekström Ice Shelf
genre Antarc*
Antarctica
Dronning Maud Land
East Antarctica
Ice Sheet
Ice Shelf
Ice Shelves
genre_facet Antarc*
Antarctica
Dronning Maud Land
East Antarctica
Ice Sheet
Ice Shelf
Ice Shelves
op_source eISSN: 1994-0424
op_relation doi:10.5194/tc-16-2051-2022
https://tc.copernicus.org/articles/16/2051/2022/
op_doi https://doi.org/10.5194/tc-16-2051-2022
container_title The Cryosphere
container_volume 16
container_issue 5
container_start_page 2051
op_container_end_page 2066
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