Evaluating quaternary glacial till sheet volume and duration of grounding events using sediment flux calculations in the Eastern basin paleotroughs, Ross Sea, Anarctica

A sequence of three seismically-resolvable, back-stepping grounding zone wedges (GZWs) within the Glomar-Challenger Basin paleo-ice-stream trough is conventionally interpreted to have been deposited by the West Antarctic Ice Sheet (WAIS) since the end of the Last Glacial Maximum (LGM). For this to b...

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Main Author: Kirst, Logan Gregory
Format: Text
Language:unknown
Published: LSU Digital Commons 2013
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Online Access:https://digitalcommons.lsu.edu/gradschool_theses/65
https://doi.org/10.31390/gradschool_theses.65
https://digitalcommons.lsu.edu/context/gradschool_theses/article/1064/viewcontent/uc.pdf
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spelling ftlouisianastuir:oai:digitalcommons.lsu.edu:gradschool_theses-1064 2023-06-11T04:05:56+02:00 Evaluating quaternary glacial till sheet volume and duration of grounding events using sediment flux calculations in the Eastern basin paleotroughs, Ross Sea, Anarctica Kirst, Logan Gregory 2013-01-01T08:00:00Z application/pdf https://digitalcommons.lsu.edu/gradschool_theses/65 https://doi.org/10.31390/gradschool_theses.65 https://digitalcommons.lsu.edu/context/gradschool_theses/article/1064/viewcontent/uc.pdf unknown LSU Digital Commons https://digitalcommons.lsu.edu/gradschool_theses/65 doi:10.31390/gradschool_theses.65 https://digitalcommons.lsu.edu/context/gradschool_theses/article/1064/viewcontent/uc.pdf LSU Master's Theses Last Glacial Maximum Glaciology Seismic Stratigraphy Earth Sciences text 2013 ftlouisianastuir https://doi.org/10.31390/gradschool_theses.65 2023-05-28T18:56:25Z A sequence of three seismically-resolvable, back-stepping grounding zone wedges (GZWs) within the Glomar-Challenger Basin paleo-ice-stream trough is conventionally interpreted to have been deposited by the West Antarctic Ice Sheet (WAIS) since the end of the Last Glacial Maximum (LGM). For this to be true, there would have to have been voluminous GZW deposition via fast moving ice streams with high sediment flux during the short timeframe since the WAIS retreat began at 11 Ka 14C BP and when the WAIS moved south of Roosevelt Island at 3.2 Ka BP. In contrast to this interpretation of how the near-surface stratigraphy relates to post-LGM retreat of the WAIS, foraminiferal radiocarbon dates from Bart and Cone (2012) suggest that the youngest back-stepped GZW corresponds to the culmination of erosion and deposition during the LGM. If so, the older GZWs currently assigned to the post LGM time frame would need to be reassigned to pre-LGM glacial cycles. To test which of these interpretations is correct, the duration of the Brown Unit, the second of the three backstepped GZWs, was investigated in detail. Five seismic surveys from eastern Ross Sea were used to map the extent and thickness of the Brown Unit. Two end-member durations were deduced using 3D sediment flux values that would have existed were the WAIS in retreat mode versus advance mode. Utilizing the retreat-mode flux, a 5.12 ± 1 ky grounding event duration was calculated for the Brown Unit GZW. However, a 512.88 ± 100 ky grounding event duration was determined using the advance-mode sediment flux. Given the durations previously calculated for the Gray Unit (the youngest post-LGM GZW) from Bart and Owolana (2012) and the grounding event duration recently calculated for the Red Unit (the oldest post-LGM GZW) by Bowles (2013) suggests that the near surface stratigraphy must represent the amalgamation of erosion and deposition from many cycles of WAIS advance and retreat. In particular, the Brown Unit is tentatively assigned to time elapsed between MIS5 and MIS8. Text Antarc* Antarctic Ice Sheet Roosevelt Island Ross Sea LSU Digital Commons (Louisiana State University) Antarctic Bowles ENVELOPE(-54.091,-54.091,-61.318,-61.318) Glomar Challenger Basin ENVELOPE(180.000,180.000,-77.750,-77.750) Roosevelt Island ENVELOPE(-162.000,-162.000,-79.283,-79.283) Ross Sea West Antarctic Ice Sheet
institution Open Polar
collection LSU Digital Commons (Louisiana State University)
op_collection_id ftlouisianastuir
language unknown
topic Last Glacial Maximum
Glaciology
Seismic Stratigraphy
Earth Sciences
spellingShingle Last Glacial Maximum
Glaciology
Seismic Stratigraphy
Earth Sciences
Kirst, Logan Gregory
Evaluating quaternary glacial till sheet volume and duration of grounding events using sediment flux calculations in the Eastern basin paleotroughs, Ross Sea, Anarctica
topic_facet Last Glacial Maximum
Glaciology
Seismic Stratigraphy
Earth Sciences
description A sequence of three seismically-resolvable, back-stepping grounding zone wedges (GZWs) within the Glomar-Challenger Basin paleo-ice-stream trough is conventionally interpreted to have been deposited by the West Antarctic Ice Sheet (WAIS) since the end of the Last Glacial Maximum (LGM). For this to be true, there would have to have been voluminous GZW deposition via fast moving ice streams with high sediment flux during the short timeframe since the WAIS retreat began at 11 Ka 14C BP and when the WAIS moved south of Roosevelt Island at 3.2 Ka BP. In contrast to this interpretation of how the near-surface stratigraphy relates to post-LGM retreat of the WAIS, foraminiferal radiocarbon dates from Bart and Cone (2012) suggest that the youngest back-stepped GZW corresponds to the culmination of erosion and deposition during the LGM. If so, the older GZWs currently assigned to the post LGM time frame would need to be reassigned to pre-LGM glacial cycles. To test which of these interpretations is correct, the duration of the Brown Unit, the second of the three backstepped GZWs, was investigated in detail. Five seismic surveys from eastern Ross Sea were used to map the extent and thickness of the Brown Unit. Two end-member durations were deduced using 3D sediment flux values that would have existed were the WAIS in retreat mode versus advance mode. Utilizing the retreat-mode flux, a 5.12 ± 1 ky grounding event duration was calculated for the Brown Unit GZW. However, a 512.88 ± 100 ky grounding event duration was determined using the advance-mode sediment flux. Given the durations previously calculated for the Gray Unit (the youngest post-LGM GZW) from Bart and Owolana (2012) and the grounding event duration recently calculated for the Red Unit (the oldest post-LGM GZW) by Bowles (2013) suggests that the near surface stratigraphy must represent the amalgamation of erosion and deposition from many cycles of WAIS advance and retreat. In particular, the Brown Unit is tentatively assigned to time elapsed between MIS5 and MIS8.
format Text
author Kirst, Logan Gregory
author_facet Kirst, Logan Gregory
author_sort Kirst, Logan Gregory
title Evaluating quaternary glacial till sheet volume and duration of grounding events using sediment flux calculations in the Eastern basin paleotroughs, Ross Sea, Anarctica
title_short Evaluating quaternary glacial till sheet volume and duration of grounding events using sediment flux calculations in the Eastern basin paleotroughs, Ross Sea, Anarctica
title_full Evaluating quaternary glacial till sheet volume and duration of grounding events using sediment flux calculations in the Eastern basin paleotroughs, Ross Sea, Anarctica
title_fullStr Evaluating quaternary glacial till sheet volume and duration of grounding events using sediment flux calculations in the Eastern basin paleotroughs, Ross Sea, Anarctica
title_full_unstemmed Evaluating quaternary glacial till sheet volume and duration of grounding events using sediment flux calculations in the Eastern basin paleotroughs, Ross Sea, Anarctica
title_sort evaluating quaternary glacial till sheet volume and duration of grounding events using sediment flux calculations in the eastern basin paleotroughs, ross sea, anarctica
publisher LSU Digital Commons
publishDate 2013
url https://digitalcommons.lsu.edu/gradschool_theses/65
https://doi.org/10.31390/gradschool_theses.65
https://digitalcommons.lsu.edu/context/gradschool_theses/article/1064/viewcontent/uc.pdf
long_lat ENVELOPE(-54.091,-54.091,-61.318,-61.318)
ENVELOPE(180.000,180.000,-77.750,-77.750)
ENVELOPE(-162.000,-162.000,-79.283,-79.283)
geographic Antarctic
Bowles
Glomar Challenger Basin
Roosevelt Island
Ross Sea
West Antarctic Ice Sheet
geographic_facet Antarctic
Bowles
Glomar Challenger Basin
Roosevelt Island
Ross Sea
West Antarctic Ice Sheet
genre Antarc*
Antarctic
Ice Sheet
Roosevelt Island
Ross Sea
genre_facet Antarc*
Antarctic
Ice Sheet
Roosevelt Island
Ross Sea
op_source LSU Master's Theses
op_relation https://digitalcommons.lsu.edu/gradschool_theses/65
doi:10.31390/gradschool_theses.65
https://digitalcommons.lsu.edu/context/gradschool_theses/article/1064/viewcontent/uc.pdf
op_doi https://doi.org/10.31390/gradschool_theses.65
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