Reconstruction of Antarctic Cenozoic Paleoenvironments Through Palynological Analysis of Subglacial Lake and Ice Stream Sediments
The West Antarctic Ice Sheet (WAIS), with a large portion being grounded below sea level, is historically known for its instability. Timing and evaluating the magnitude of WAIS advance and retreat is essential to improve our understanding of control mechanisms. The scarcity of accessible subglacial...
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ftlouisianastuir:oai:repository.lsu.edu:gradschool_theses-5731 2024-09-15T17:45:09+00:00 Reconstruction of Antarctic Cenozoic Paleoenvironments Through Palynological Analysis of Subglacial Lake and Ice Stream Sediments Baudoin, Patrick 2018-05-17T07:00:00Z application/pdf https://repository.lsu.edu/gradschool_theses/4721 https://doi.org/10.31390/gradschool_theses.4721 https://repository.lsu.edu/context/gradschool_theses/article/5731/viewcontent/FINAL_THESIS_with_EDITS.pdf unknown LSU Scholarly Repository https://repository.lsu.edu/gradschool_theses/4721 doi:10.31390/gradschool_theses.4721 https://repository.lsu.edu/context/gradschool_theses/article/5731/viewcontent/FINAL_THESIS_with_EDITS.pdf LSU Master's Theses Palynology Antarctica Ice stream Subglacial Siple Coast Geology text 2018 ftlouisianastuir https://doi.org/10.31390/gradschool_theses.4721 2024-08-08T04:27:14Z The West Antarctic Ice Sheet (WAIS), with a large portion being grounded below sea level, is historically known for its instability. Timing and evaluating the magnitude of WAIS advance and retreat is essential to improve our understanding of control mechanisms. The scarcity of accessible subglacial geology in areas such as the Siple Coast in West Antarctica limits our understanding and ability to gauge WAIS response to environmental changes. To evaluate the ice-sheet history around the Siple Coast, i.e., when it was last covered by vegetation, access to sediment immediately below the ice-sheet is essential. In the absence of large-scale drilling, such as ANDRILL, in this region, sediments were sampled by targeting basal tills. Palynological analysis was conducted on ninety-one sample of West Antarctic subglacial till, shallow subsurface sediments, and grounding zone wedge sediments from the Bindschadler Ice Stream (BIS), Kamb Ice Stream (KIS), Whillans Ice Stream (WIS), Subglacial Lake Whillans (SLW), the Whillans Grounding Zone (WGZ), and the Ross Ice Shelf Project (RISP). Based on two key dinoflagellate cysts and pollen and spores recovered, the age of the youngest assemblage (last vegetation) is estimated to be between 60 and 30 Ma. Our results show that the bulk of the vegetation likely disappeared between 33 to 30 Ma. We acknowledge that some of the tundra vegetation recovered could be as young as Oligocene, as the absence of post-Eocene age dinoflagellate cysts could be a result of limiting environmental sea-surface conditions. Palynomorphs recovered indicate differences between sites. BIS and KIS have the highest terrestrial palynomorph concentrations observed by more than double all other sites combined, and also are composed of a high abundance of moss spores. WIS, SLW, and WGZ are primarily composed of a large diversity of Nothofagidites spp., indicating the presence of rich and diverse beech forests – a diversity typical of Eocene times. The difference in assemblages confirms that the catchment ... Text Antarc* Antarctic Antarctica Bindschadler Ice Stream Ice Sheet Ice Shelf Kamb Ice Stream Ross Ice Shelf Tundra West Antarctica Whillans Ice Stream LSU Digital Commons (Louisiana State University) |
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LSU Digital Commons (Louisiana State University) |
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topic |
Palynology Antarctica Ice stream Subglacial Siple Coast Geology |
spellingShingle |
Palynology Antarctica Ice stream Subglacial Siple Coast Geology Baudoin, Patrick Reconstruction of Antarctic Cenozoic Paleoenvironments Through Palynological Analysis of Subglacial Lake and Ice Stream Sediments |
topic_facet |
Palynology Antarctica Ice stream Subglacial Siple Coast Geology |
description |
The West Antarctic Ice Sheet (WAIS), with a large portion being grounded below sea level, is historically known for its instability. Timing and evaluating the magnitude of WAIS advance and retreat is essential to improve our understanding of control mechanisms. The scarcity of accessible subglacial geology in areas such as the Siple Coast in West Antarctica limits our understanding and ability to gauge WAIS response to environmental changes. To evaluate the ice-sheet history around the Siple Coast, i.e., when it was last covered by vegetation, access to sediment immediately below the ice-sheet is essential. In the absence of large-scale drilling, such as ANDRILL, in this region, sediments were sampled by targeting basal tills. Palynological analysis was conducted on ninety-one sample of West Antarctic subglacial till, shallow subsurface sediments, and grounding zone wedge sediments from the Bindschadler Ice Stream (BIS), Kamb Ice Stream (KIS), Whillans Ice Stream (WIS), Subglacial Lake Whillans (SLW), the Whillans Grounding Zone (WGZ), and the Ross Ice Shelf Project (RISP). Based on two key dinoflagellate cysts and pollen and spores recovered, the age of the youngest assemblage (last vegetation) is estimated to be between 60 and 30 Ma. Our results show that the bulk of the vegetation likely disappeared between 33 to 30 Ma. We acknowledge that some of the tundra vegetation recovered could be as young as Oligocene, as the absence of post-Eocene age dinoflagellate cysts could be a result of limiting environmental sea-surface conditions. Palynomorphs recovered indicate differences between sites. BIS and KIS have the highest terrestrial palynomorph concentrations observed by more than double all other sites combined, and also are composed of a high abundance of moss spores. WIS, SLW, and WGZ are primarily composed of a large diversity of Nothofagidites spp., indicating the presence of rich and diverse beech forests – a diversity typical of Eocene times. The difference in assemblages confirms that the catchment ... |
format |
Text |
author |
Baudoin, Patrick |
author_facet |
Baudoin, Patrick |
author_sort |
Baudoin, Patrick |
title |
Reconstruction of Antarctic Cenozoic Paleoenvironments Through Palynological Analysis of Subglacial Lake and Ice Stream Sediments |
title_short |
Reconstruction of Antarctic Cenozoic Paleoenvironments Through Palynological Analysis of Subglacial Lake and Ice Stream Sediments |
title_full |
Reconstruction of Antarctic Cenozoic Paleoenvironments Through Palynological Analysis of Subglacial Lake and Ice Stream Sediments |
title_fullStr |
Reconstruction of Antarctic Cenozoic Paleoenvironments Through Palynological Analysis of Subglacial Lake and Ice Stream Sediments |
title_full_unstemmed |
Reconstruction of Antarctic Cenozoic Paleoenvironments Through Palynological Analysis of Subglacial Lake and Ice Stream Sediments |
title_sort |
reconstruction of antarctic cenozoic paleoenvironments through palynological analysis of subglacial lake and ice stream sediments |
publisher |
LSU Scholarly Repository |
publishDate |
2018 |
url |
https://repository.lsu.edu/gradschool_theses/4721 https://doi.org/10.31390/gradschool_theses.4721 https://repository.lsu.edu/context/gradschool_theses/article/5731/viewcontent/FINAL_THESIS_with_EDITS.pdf |
genre |
Antarc* Antarctic Antarctica Bindschadler Ice Stream Ice Sheet Ice Shelf Kamb Ice Stream Ross Ice Shelf Tundra West Antarctica Whillans Ice Stream |
genre_facet |
Antarc* Antarctic Antarctica Bindschadler Ice Stream Ice Sheet Ice Shelf Kamb Ice Stream Ross Ice Shelf Tundra West Antarctica Whillans Ice Stream |
op_source |
LSU Master's Theses |
op_relation |
https://repository.lsu.edu/gradschool_theses/4721 doi:10.31390/gradschool_theses.4721 https://repository.lsu.edu/context/gradschool_theses/article/5731/viewcontent/FINAL_THESIS_with_EDITS.pdf |
op_doi |
https://doi.org/10.31390/gradschool_theses.4721 |
_version_ |
1810492871064682496 |