Details
| Original language | English |
|---|---|
| Pages (from-to) | 2051-2066 |
| Number of pages | 16 |
| Journal | CRYOSPHERE |
| Volume | 16 |
| Issue number | 5 |
| Publication status | Published - 30 May 2022 |
| Externally published | Yes |
Abstract
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 11km away from the continental shelf break, indicating the most recent minimal extent of grounded ice in this region. Beneath the front 1/430km 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 45m 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 320m, 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 ice-sheet models in this severely understudied region.
ASJC Scopus subject areas
- Environmental Science(all)
- Water Science and Technology
- Earth and Planetary Sciences(all)
- Earth-Surface Processes
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In: CRYOSPHERE, Vol. 16, No. 5, 30.05.2022, p. 2051-2066.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Geomorphology and shallow sub-sea-floor structures underneath the Ekström Ice Shelf, Antarctica
AU - Oetting, Astrid
AU - Smith, Emma C.
AU - Arndt, Jan Erik
AU - Dorschel, Boris
AU - Drews, Reinhard
AU - Ehlers, Todd A.
AU - Gaedicke, Christoph
AU - Hofstede, Coen
AU - Klages, Johann P.
AU - Kuhn, Gerhard
AU - Lambrecht, Astrid
AU - Läufer, Andreas
AU - Mayer, Christoph
AU - Tiedemann, Ralf
AU - Wilhelms, Frank
AU - Eisen, Olaf
N1 - Funding Information: 2016 were funded through the AWI-BGR Sub-EIS-Obs project. ECS was additionally partly funded through the DFG COST-S2S project grant EI672/10-1 in the framework of the priority program “Antarctic Research with comparative investigations in Arctic ice areas”. Fieldwork was supported by the large-scale research infrastructure Neumayer III and Polarstern (Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung, 2016, 2017). RD was supported by an Emmy Noether Grant of the Deutsche Forschungsgemeinschft (DR 822/3-1).
PY - 2022/5/30
Y1 - 2022/5/30
N2 - 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 11km away from the continental shelf break, indicating the most recent minimal extent of grounded ice in this region. Beneath the front 1/430km 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 45m 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 320m, 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 ice-sheet models in this severely understudied region.
AB - 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 11km away from the continental shelf break, indicating the most recent minimal extent of grounded ice in this region. Beneath the front 1/430km 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 45m 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 320m, 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 ice-sheet models in this severely understudied region.
UR - http://www.scopus.com/inward/record.url?scp=85131511709&partnerID=8YFLogxK
U2 - 10.5194/tc-16-2051-2022
DO - 10.5194/tc-16-2051-2022
M3 - Article
AN - SCOPUS:85131511709
VL - 16
SP - 2051
EP - 2066
JO - CRYOSPHERE
JF - CRYOSPHERE
SN - 1994-0416
IS - 5
ER -