Limited grounding-line advance onto the West Antarctic continental shelf in the easternmost Amundsen Sea Embayment during the last glacial period
Precise knowledge about the extent of the West Antarctic Ice Sheet (WAIS) at the Last Glacial Maximum (LGM; c. 26.5–19 cal. ka BP) is important in order to 1) improve paleo-ice sheet reconstructions, 2) provide a robust empirical framework for calibrating paleo-ice sheet models, and 3) locate potent...
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ftcolumbiauniv:oai:academiccommons.columbia.edu:10.7916/D8TF08WX 2023-05-15T13:23:44+02:00 Limited grounding-line advance onto the West Antarctic continental shelf in the easternmost Amundsen Sea Embayment during the last glacial period Klages, Johann P. Kuhn, Gerhard Hillenbrand, Claus-Dieter Smith, James A. Graham, Alastair G. C. Nitsche, Frank Oliver Frederichs, Thomas Jernas, Patrycja E. Gohl, Karsten Wacker, Lukas 2017 https://doi.org/10.7916/D8TF08WX English eng https://doi.org/10.7916/D8TF08WX Environmental sciences Last Glacial Maximum Ice sheets Paleoceanography Articles 2017 ftcolumbiauniv https://doi.org/10.7916/D8TF08WX 2019-04-04T08:16:25Z Precise knowledge about the extent of the West Antarctic Ice Sheet (WAIS) at the Last Glacial Maximum (LGM; c. 26.5–19 cal. ka BP) is important in order to 1) improve paleo-ice sheet reconstructions, 2) provide a robust empirical framework for calibrating paleo-ice sheet models, and 3) locate potential shelf refugia for Antarctic benthos during the last glacial period. However, reliable reconstructions are still lacking for many WAIS sectors, particularly for key areas on the outer continental shelf, where the LGM-ice sheet is assumed to have terminated. In many areas of the outer continental shelf around Antarctica, direct geological data for the presence or absence of grounded ice during the LGM is lacking because of post-LGM iceberg scouring. This also applies to most of the outer continental shelf in the Amundsen Sea. Here we present detailed marine geophysical and new geological data documenting a sequence of glaciomarine sediments up to ~12 m thick within the deep outer portion of Abbot Trough, a palaeo-ice stream trough on the outer shelf of the Amundsen Sea Embayment. The upper 2–3 meters of this sediment drape contain calcareous foraminifera of Holocene and (pre-)LGM age and, in combination with palaeomagnetic age constraints, indicate that continuous glaciomarine deposition persisted here since well before the LGM, possibly even since the last interglacial period. Our data therefore indicate that the LGM grounding line, whose exact location was previously uncertain, did not reach the shelf edge everywhere in the Amundsen Sea. The LGM grounding line position coincides with the crest of a distinct grounding-zone wedge ~100 km inland from the continental shelf edge. Thus, an area of ≥6000 km2 remained free of grounded ice through the last glacial cycle, requiring the LGM grounding line position to be re-located in this sector, and suggesting a new site at which Antarctic shelf benthos may have survived the last glacial period. Article in Journal/Newspaper Amundsen Sea Antarc* Antarctic Antarctica Ice Sheet Iceberg* Columbia University: Academic Commons Antarctic Amundsen Sea West Antarctic Ice Sheet |
institution |
Open Polar |
collection |
Columbia University: Academic Commons |
op_collection_id |
ftcolumbiauniv |
language |
English |
topic |
Environmental sciences Last Glacial Maximum Ice sheets Paleoceanography |
spellingShingle |
Environmental sciences Last Glacial Maximum Ice sheets Paleoceanography Klages, Johann P. Kuhn, Gerhard Hillenbrand, Claus-Dieter Smith, James A. Graham, Alastair G. C. Nitsche, Frank Oliver Frederichs, Thomas Jernas, Patrycja E. Gohl, Karsten Wacker, Lukas Limited grounding-line advance onto the West Antarctic continental shelf in the easternmost Amundsen Sea Embayment during the last glacial period |
topic_facet |
Environmental sciences Last Glacial Maximum Ice sheets Paleoceanography |
description |
Precise knowledge about the extent of the West Antarctic Ice Sheet (WAIS) at the Last Glacial Maximum (LGM; c. 26.5–19 cal. ka BP) is important in order to 1) improve paleo-ice sheet reconstructions, 2) provide a robust empirical framework for calibrating paleo-ice sheet models, and 3) locate potential shelf refugia for Antarctic benthos during the last glacial period. However, reliable reconstructions are still lacking for many WAIS sectors, particularly for key areas on the outer continental shelf, where the LGM-ice sheet is assumed to have terminated. In many areas of the outer continental shelf around Antarctica, direct geological data for the presence or absence of grounded ice during the LGM is lacking because of post-LGM iceberg scouring. This also applies to most of the outer continental shelf in the Amundsen Sea. Here we present detailed marine geophysical and new geological data documenting a sequence of glaciomarine sediments up to ~12 m thick within the deep outer portion of Abbot Trough, a palaeo-ice stream trough on the outer shelf of the Amundsen Sea Embayment. The upper 2–3 meters of this sediment drape contain calcareous foraminifera of Holocene and (pre-)LGM age and, in combination with palaeomagnetic age constraints, indicate that continuous glaciomarine deposition persisted here since well before the LGM, possibly even since the last interglacial period. Our data therefore indicate that the LGM grounding line, whose exact location was previously uncertain, did not reach the shelf edge everywhere in the Amundsen Sea. The LGM grounding line position coincides with the crest of a distinct grounding-zone wedge ~100 km inland from the continental shelf edge. Thus, an area of ≥6000 km2 remained free of grounded ice through the last glacial cycle, requiring the LGM grounding line position to be re-located in this sector, and suggesting a new site at which Antarctic shelf benthos may have survived the last glacial period. |
format |
Article in Journal/Newspaper |
author |
Klages, Johann P. Kuhn, Gerhard Hillenbrand, Claus-Dieter Smith, James A. Graham, Alastair G. C. Nitsche, Frank Oliver Frederichs, Thomas Jernas, Patrycja E. Gohl, Karsten Wacker, Lukas |
author_facet |
Klages, Johann P. Kuhn, Gerhard Hillenbrand, Claus-Dieter Smith, James A. Graham, Alastair G. C. Nitsche, Frank Oliver Frederichs, Thomas Jernas, Patrycja E. Gohl, Karsten Wacker, Lukas |
author_sort |
Klages, Johann P. |
title |
Limited grounding-line advance onto the West Antarctic continental shelf in the easternmost Amundsen Sea Embayment during the last glacial period |
title_short |
Limited grounding-line advance onto the West Antarctic continental shelf in the easternmost Amundsen Sea Embayment during the last glacial period |
title_full |
Limited grounding-line advance onto the West Antarctic continental shelf in the easternmost Amundsen Sea Embayment during the last glacial period |
title_fullStr |
Limited grounding-line advance onto the West Antarctic continental shelf in the easternmost Amundsen Sea Embayment during the last glacial period |
title_full_unstemmed |
Limited grounding-line advance onto the West Antarctic continental shelf in the easternmost Amundsen Sea Embayment during the last glacial period |
title_sort |
limited grounding-line advance onto the west antarctic continental shelf in the easternmost amundsen sea embayment during the last glacial period |
publishDate |
2017 |
url |
https://doi.org/10.7916/D8TF08WX |
geographic |
Antarctic Amundsen Sea West Antarctic Ice Sheet |
geographic_facet |
Antarctic Amundsen Sea West Antarctic Ice Sheet |
genre |
Amundsen Sea Antarc* Antarctic Antarctica Ice Sheet Iceberg* |
genre_facet |
Amundsen Sea Antarc* Antarctic Antarctica Ice Sheet Iceberg* |
op_relation |
https://doi.org/10.7916/D8TF08WX |
op_doi |
https://doi.org/10.7916/D8TF08WX |
_version_ |
1766374484543012864 |