Past ice sheet–seabed interactions in the northeastern Weddell Sea embayment, Antarctica
<p>The Antarctic ice sheet extent in the Weddell Sea embayment (WSE) during the Last Glacial Maximum (LGM; ca. 19–25 calibrated kiloyears before present, ka cal BP) and its subsequent retreat from the shelf are poorly constrained, with two conflicting scenarios being disc...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-06-01
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| Series: | The Cryosphere |
| Online Access: | https://tc.copernicus.org/articles/14/2115/2020/tc-14-2115-2020.pdf |
| Summary: | <p>The Antarctic ice sheet extent in the Weddell Sea
embayment (WSE) during the Last Glacial Maximum (LGM; ca. 19–25 calibrated
kiloyears before present, ka cal BP) and its subsequent retreat from the
shelf are poorly constrained, with two conflicting scenarios being
discussed. Today, the modern Brunt Ice Shelf, the last remaining ice shelf
in the northeastern WSE, is only pinned at a single location and recent
crevasse development may lead to its rapid disintegration in the near
future. We investigated the seafloor morphology on the northeastern WSE
shelf and discuss its implications, in combination with marine geological
records, to create reconstructions of the past behaviour of this sector of the
East Antarctic Ice Sheet (EAIS), including ice–seafloor interactions. Our
data show that an ice stream flowed through Stancomb-Wills Trough and acted
as the main conduit for EAIS drainage during the LGM in this sector.
Post-LGM ice stream retreat occurred stepwise, with at least three
documented grounding-line still-stands, and the trough had become free of
grounded ice by <span class="inline-formula">∼10.5</span> ka cal BP. In contrast, slow-flowing
ice once covered the shelf in Brunt Basin and extended westwards toward
McDonald Bank. During a later time period, only floating ice was present
within Brunt Basin, but large “ice slabs” enclosed within the ice shelf
occasionally ran aground at the eastern side of McDonald Bank, forming 10
unusual ramp-shaped seabed features. These ramps are the result of temporary
ice shelf grounding events buttressing the ice further upstream. To the west
of this area, Halley Trough very likely was free of grounded ice during the
LGM, representing a potential refuge for benthic shelf fauna at this time.</p> |
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| ISSN: | 1994-0416 1994-0424 |