Gravity analyses for the crustal structure and subglacial geology of West Antarctica, particularly beneath Thwaites Glacier
text The West Antarctic Ice Sheet (WAIS) is mostly grounded in broad, deep basins (down to 2.5 km below sea level) that are stretched between five crustal blocks. The geometry of the bedrock, being mostly below sea level, induces a fundamental instability in the WAIS through the possibility of runaw...
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ftunivtexas:oai:repositories.lib.utexas.edu:2152/18359 2023-05-15T13:44:26+02:00 Gravity analyses for the crustal structure and subglacial geology of West Antarctica, particularly beneath Thwaites Glacier Diehl, Theresa Marie, 1981- Blankenship, Donald D. 2008-08 electronic application/pdf http://hdl.handle.net/2152/18359 eng eng http://hdl.handle.net/2152/18359 Copyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works. Gravity anomalies--Antarctica--Thwaites Glacier Gravity anomalies--Antarctica--Computer simulation Geology Structural--Antarctica--Thwaites Glacier Thwaites Glacier (Antarctica) Sedimentary basins--Antarctica Geology--Antarctica 2008 ftunivtexas 2020-12-23T22:17:47Z text The West Antarctic Ice Sheet (WAIS) is mostly grounded in broad, deep basins (down to 2.5 km below sea level) that are stretched between five crustal blocks. The geometry of the bedrock, being mostly below sea level, induces a fundamental instability in the WAIS through the possibility of runaway grounding line retreat. The crustal environment of the WAIS further influences the ice sheet’s fast flow through conditions at the ice-bedrock boundary. This study focuses on understanding the WAIS by examining the subglacial geology (such as volcanoes and sedimentary basins) at the icebedrock boundary and the continent’s deeper crustal structure- primarily using airborne gravity anomalies. The keystone of this study is a 2004-2005 aerogeophysical survey over one of the most negative mass balance glaciers on the continent: Thwaites Glacier (TG). The gravity anomalies derived from this dataset- as well as gravity-based modeling and spectral crustal boundary depth estimates- reveal a heterogeneous crustal environment beneath the glacier. The widespread Mesozoic rifting observed in the Ross Sea Embayment (RSE) of West Antarctica extends beneath TG, where the crust is ~27 km thick and cool. Adjacent to TG, spectrally-derived shallow Moho depths for the Marie Byrd Land (MBL) crustal block can be explained by thermal support from warm mantle. I assemble here new compilations of free-air and Bouguer gravity anomalies across West Antarctica (from both airborne and satellite datasets) and re-interpret the extents of West Antarctic crustal block and their boundaries with the rift system. Airy isostatic gravity anomalies reveal that TG is relatively sediment starved, in contrast to the sediment-rich RSE. TG’s fast flow velocities could be sustained in this sediment poor environment if higher heat flux in MBL was providing an ample source of subglacial melt water to the glacier. The isostatic anomalies also indicate that TG’s outlet rests on a bedrock sill that will impede future grounding line retreat (up to ~100 km) and temporarily stabilize the glacier. Geological Sciences Other/Unknown Material Antarc* Antarctic Antarctica Ice Sheet Marie Byrd Land Ross Sea Thwaites Glacier West Antarctica The University of Texas at Austin: Texas ScholarWorks Antarctic Ross Sea West Antarctica West Antarctic Ice Sheet Byrd Marie Byrd Land ENVELOPE(-130.000,-130.000,-78.000,-78.000) Thwaites Glacier ENVELOPE(-106.750,-106.750,-75.500,-75.500) |
institution |
Open Polar |
collection |
The University of Texas at Austin: Texas ScholarWorks |
op_collection_id |
ftunivtexas |
language |
English |
topic |
Gravity anomalies--Antarctica--Thwaites Glacier Gravity anomalies--Antarctica--Computer simulation Geology Structural--Antarctica--Thwaites Glacier Thwaites Glacier (Antarctica) Sedimentary basins--Antarctica Geology--Antarctica |
spellingShingle |
Gravity anomalies--Antarctica--Thwaites Glacier Gravity anomalies--Antarctica--Computer simulation Geology Structural--Antarctica--Thwaites Glacier Thwaites Glacier (Antarctica) Sedimentary basins--Antarctica Geology--Antarctica Diehl, Theresa Marie, 1981- Gravity analyses for the crustal structure and subglacial geology of West Antarctica, particularly beneath Thwaites Glacier |
topic_facet |
Gravity anomalies--Antarctica--Thwaites Glacier Gravity anomalies--Antarctica--Computer simulation Geology Structural--Antarctica--Thwaites Glacier Thwaites Glacier (Antarctica) Sedimentary basins--Antarctica Geology--Antarctica |
description |
text The West Antarctic Ice Sheet (WAIS) is mostly grounded in broad, deep basins (down to 2.5 km below sea level) that are stretched between five crustal blocks. The geometry of the bedrock, being mostly below sea level, induces a fundamental instability in the WAIS through the possibility of runaway grounding line retreat. The crustal environment of the WAIS further influences the ice sheet’s fast flow through conditions at the ice-bedrock boundary. This study focuses on understanding the WAIS by examining the subglacial geology (such as volcanoes and sedimentary basins) at the icebedrock boundary and the continent’s deeper crustal structure- primarily using airborne gravity anomalies. The keystone of this study is a 2004-2005 aerogeophysical survey over one of the most negative mass balance glaciers on the continent: Thwaites Glacier (TG). The gravity anomalies derived from this dataset- as well as gravity-based modeling and spectral crustal boundary depth estimates- reveal a heterogeneous crustal environment beneath the glacier. The widespread Mesozoic rifting observed in the Ross Sea Embayment (RSE) of West Antarctica extends beneath TG, where the crust is ~27 km thick and cool. Adjacent to TG, spectrally-derived shallow Moho depths for the Marie Byrd Land (MBL) crustal block can be explained by thermal support from warm mantle. I assemble here new compilations of free-air and Bouguer gravity anomalies across West Antarctica (from both airborne and satellite datasets) and re-interpret the extents of West Antarctic crustal block and their boundaries with the rift system. Airy isostatic gravity anomalies reveal that TG is relatively sediment starved, in contrast to the sediment-rich RSE. TG’s fast flow velocities could be sustained in this sediment poor environment if higher heat flux in MBL was providing an ample source of subglacial melt water to the glacier. The isostatic anomalies also indicate that TG’s outlet rests on a bedrock sill that will impede future grounding line retreat (up to ~100 km) and temporarily stabilize the glacier. Geological Sciences |
author2 |
Blankenship, Donald D. |
author |
Diehl, Theresa Marie, 1981- |
author_facet |
Diehl, Theresa Marie, 1981- |
author_sort |
Diehl, Theresa Marie, 1981- |
title |
Gravity analyses for the crustal structure and subglacial geology of West Antarctica, particularly beneath Thwaites Glacier |
title_short |
Gravity analyses for the crustal structure and subglacial geology of West Antarctica, particularly beneath Thwaites Glacier |
title_full |
Gravity analyses for the crustal structure and subglacial geology of West Antarctica, particularly beneath Thwaites Glacier |
title_fullStr |
Gravity analyses for the crustal structure and subglacial geology of West Antarctica, particularly beneath Thwaites Glacier |
title_full_unstemmed |
Gravity analyses for the crustal structure and subglacial geology of West Antarctica, particularly beneath Thwaites Glacier |
title_sort |
gravity analyses for the crustal structure and subglacial geology of west antarctica, particularly beneath thwaites glacier |
publishDate |
2008 |
url |
http://hdl.handle.net/2152/18359 |
long_lat |
ENVELOPE(-130.000,-130.000,-78.000,-78.000) ENVELOPE(-106.750,-106.750,-75.500,-75.500) |
geographic |
Antarctic Ross Sea West Antarctica West Antarctic Ice Sheet Byrd Marie Byrd Land Thwaites Glacier |
geographic_facet |
Antarctic Ross Sea West Antarctica West Antarctic Ice Sheet Byrd Marie Byrd Land Thwaites Glacier |
genre |
Antarc* Antarctic Antarctica Ice Sheet Marie Byrd Land Ross Sea Thwaites Glacier West Antarctica |
genre_facet |
Antarc* Antarctic Antarctica Ice Sheet Marie Byrd Land Ross Sea Thwaites Glacier West Antarctica |
op_relation |
http://hdl.handle.net/2152/18359 |
op_rights |
Copyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works. |
_version_ |
1766201654040854528 |