West Antarctic ice sheet retreat chronology of two middle-shelf grounding-zone wedges in Eastern Basin, Ross Sea, Antarctica
This study isolated a small number of large, in situ and reworked foraminifera from diamicts deposited in two grounding zone wedges on the middle continental shelf in Eastern Basin, Ross Sea, Antarctica. All samples were of sufficient weight to yield Holocene dates if the samples were indeed of Holo...
Main Author: | |
---|---|
Format: | Text |
Language: | unknown |
Published: |
LSU Digital Commons
2011
|
Subjects: | |
Online Access: | https://digitalcommons.lsu.edu/gradschool_theses/154 https://doi.org/10.31390/gradschool_theses.154 https://digitalcommons.lsu.edu/context/gradschool_theses/article/1153/viewcontent/Thesis_Copeland_Thesis.pdf |
id |
ftlouisianastuir:oai:digitalcommons.lsu.edu:gradschool_theses-1153 |
---|---|
record_format |
openpolar |
spelling |
ftlouisianastuir:oai:digitalcommons.lsu.edu:gradschool_theses-1153 2023-06-11T04:05:55+02:00 West Antarctic ice sheet retreat chronology of two middle-shelf grounding-zone wedges in Eastern Basin, Ross Sea, Antarctica Copeland, Lenora Nicole 2011-01-01T08:00:00Z application/pdf https://digitalcommons.lsu.edu/gradschool_theses/154 https://doi.org/10.31390/gradschool_theses.154 https://digitalcommons.lsu.edu/context/gradschool_theses/article/1153/viewcontent/Thesis_Copeland_Thesis.pdf unknown LSU Digital Commons https://digitalcommons.lsu.edu/gradschool_theses/154 doi:10.31390/gradschool_theses.154 https://digitalcommons.lsu.edu/context/gradschool_theses/article/1153/viewcontent/Thesis_Copeland_Thesis.pdf LSU Master's Theses Eastern Basin Antarctica Earth Sciences text 2011 ftlouisianastuir https://doi.org/10.31390/gradschool_theses.154 2023-05-28T18:57:03Z This study isolated a small number of large, in situ and reworked foraminifera from diamicts deposited in two grounding zone wedges on the middle continental shelf in Eastern Basin, Ross Sea, Antarctica. All samples were of sufficient weight to yield Holocene dates if the samples were indeed of Holocene age. Of the twelve small samples sent for radiocarbon analysis, the two heaviest were for reworked foraminifera which yielded dates of >22,200 14C BP and >22,500 14C BP. None of the other ten samples yielded radiocarbon dates. The lack of Holocene radiocarbon dates for the six in situ and four reworked foraminifera samples suggests that West Antarctic Ice Sheet (WAIS) retreated from the middle continental shelf Eastern Basin prior to the Holocene, i.e., much earlier than generally accepted. A second part of this study involved compiling all previous radiocarbon dates from Eastern Basin as well as chronologic information concerning ice-sheet retreat from the surrounding terrestrial areas. This synthesis of marine and terrestrial data suggests that the WAIS retreated from the middle continental shelf at ~26,000 14C BP. The WAIS retreat from the middle continental shelf was not associated with coeval deflation of the ice-sheet surface in the far interior reaches of West Antarctica. Instead, WAIS deflation was delayed by >13,000 years. This delay in the onset of deflation suggests that the effects of ice-sheet retreat from the middle shelf slowly propagated to the interior beginning only after the grounding line had retreated far inland. The retreat of the WAIS from the middle continental shelf towards the interior did ultimately cause deflation beginning first at Siple Dome, ¬¬¬followed by deflation at Reedy Glacier, Marie Byrd Land, and Discovery Ridge as the grounding line migrated to its present-day position. Text Antarc* Antarctic Antarctica Ice Sheet Marie Byrd Land Reedy Glacier Ross Sea West Antarctica LSU Digital Commons (Louisiana State University) Antarctic Byrd Discovery Ridge ENVELOPE(-114.100,-114.100,-84.733,-84.733) Marie Byrd Land ENVELOPE(-130.000,-130.000,-78.000,-78.000) Reedy Glacier ENVELOPE(-134.000,-134.000,-85.500,-85.500) Ross Sea Siple ENVELOPE(-83.917,-83.917,-75.917,-75.917) Siple Dome ENVELOPE(-148.833,-148.833,-81.667,-81.667) West Antarctic Ice Sheet West Antarctica |
institution |
Open Polar |
collection |
LSU Digital Commons (Louisiana State University) |
op_collection_id |
ftlouisianastuir |
language |
unknown |
topic |
Eastern Basin Antarctica Earth Sciences |
spellingShingle |
Eastern Basin Antarctica Earth Sciences Copeland, Lenora Nicole West Antarctic ice sheet retreat chronology of two middle-shelf grounding-zone wedges in Eastern Basin, Ross Sea, Antarctica |
topic_facet |
Eastern Basin Antarctica Earth Sciences |
description |
This study isolated a small number of large, in situ and reworked foraminifera from diamicts deposited in two grounding zone wedges on the middle continental shelf in Eastern Basin, Ross Sea, Antarctica. All samples were of sufficient weight to yield Holocene dates if the samples were indeed of Holocene age. Of the twelve small samples sent for radiocarbon analysis, the two heaviest were for reworked foraminifera which yielded dates of >22,200 14C BP and >22,500 14C BP. None of the other ten samples yielded radiocarbon dates. The lack of Holocene radiocarbon dates for the six in situ and four reworked foraminifera samples suggests that West Antarctic Ice Sheet (WAIS) retreated from the middle continental shelf Eastern Basin prior to the Holocene, i.e., much earlier than generally accepted. A second part of this study involved compiling all previous radiocarbon dates from Eastern Basin as well as chronologic information concerning ice-sheet retreat from the surrounding terrestrial areas. This synthesis of marine and terrestrial data suggests that the WAIS retreated from the middle continental shelf at ~26,000 14C BP. The WAIS retreat from the middle continental shelf was not associated with coeval deflation of the ice-sheet surface in the far interior reaches of West Antarctica. Instead, WAIS deflation was delayed by >13,000 years. This delay in the onset of deflation suggests that the effects of ice-sheet retreat from the middle shelf slowly propagated to the interior beginning only after the grounding line had retreated far inland. The retreat of the WAIS from the middle continental shelf towards the interior did ultimately cause deflation beginning first at Siple Dome, ¬¬¬followed by deflation at Reedy Glacier, Marie Byrd Land, and Discovery Ridge as the grounding line migrated to its present-day position. |
format |
Text |
author |
Copeland, Lenora Nicole |
author_facet |
Copeland, Lenora Nicole |
author_sort |
Copeland, Lenora Nicole |
title |
West Antarctic ice sheet retreat chronology of two middle-shelf grounding-zone wedges in Eastern Basin, Ross Sea, Antarctica |
title_short |
West Antarctic ice sheet retreat chronology of two middle-shelf grounding-zone wedges in Eastern Basin, Ross Sea, Antarctica |
title_full |
West Antarctic ice sheet retreat chronology of two middle-shelf grounding-zone wedges in Eastern Basin, Ross Sea, Antarctica |
title_fullStr |
West Antarctic ice sheet retreat chronology of two middle-shelf grounding-zone wedges in Eastern Basin, Ross Sea, Antarctica |
title_full_unstemmed |
West Antarctic ice sheet retreat chronology of two middle-shelf grounding-zone wedges in Eastern Basin, Ross Sea, Antarctica |
title_sort |
west antarctic ice sheet retreat chronology of two middle-shelf grounding-zone wedges in eastern basin, ross sea, antarctica |
publisher |
LSU Digital Commons |
publishDate |
2011 |
url |
https://digitalcommons.lsu.edu/gradschool_theses/154 https://doi.org/10.31390/gradschool_theses.154 https://digitalcommons.lsu.edu/context/gradschool_theses/article/1153/viewcontent/Thesis_Copeland_Thesis.pdf |
long_lat |
ENVELOPE(-114.100,-114.100,-84.733,-84.733) ENVELOPE(-130.000,-130.000,-78.000,-78.000) ENVELOPE(-134.000,-134.000,-85.500,-85.500) ENVELOPE(-83.917,-83.917,-75.917,-75.917) ENVELOPE(-148.833,-148.833,-81.667,-81.667) |
geographic |
Antarctic Byrd Discovery Ridge Marie Byrd Land Reedy Glacier Ross Sea Siple Siple Dome West Antarctic Ice Sheet West Antarctica |
geographic_facet |
Antarctic Byrd Discovery Ridge Marie Byrd Land Reedy Glacier Ross Sea Siple Siple Dome West Antarctic Ice Sheet West Antarctica |
genre |
Antarc* Antarctic Antarctica Ice Sheet Marie Byrd Land Reedy Glacier Ross Sea West Antarctica |
genre_facet |
Antarc* Antarctic Antarctica Ice Sheet Marie Byrd Land Reedy Glacier Ross Sea West Antarctica |
op_source |
LSU Master's Theses |
op_relation |
https://digitalcommons.lsu.edu/gradschool_theses/154 doi:10.31390/gradschool_theses.154 https://digitalcommons.lsu.edu/context/gradschool_theses/article/1153/viewcontent/Thesis_Copeland_Thesis.pdf |
op_doi |
https://doi.org/10.31390/gradschool_theses.154 |
_version_ |
1768377612185370624 |