Geophysical constraints on mantle viscosity and its influence on Antarctic glacial isostatic adjustment
Glacial isostatic adjustment (GIA) is the process by which the solid Earth responds to past and present-day changes in glaciers, ice caps, and ice sheets. This thesis focuses on vertical crustal motion of the Earth caused by GIA, which is influenced by several factors including lithosphere thickness...
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ftuvicpubl:oai:dspace.library.uvic.ca:1828/4001 2023-05-15T14:02:57+02:00 Geophysical constraints on mantle viscosity and its influence on Antarctic glacial isostatic adjustment Darlington, Andrea James, Thomas Sinclair Spence, George D. 2012 application/pdf http://hdl.handle.net/1828/4001 English en eng http://hdl.handle.net/1828/4001 Available to the World Wide Web glacial isostatic adjustment Global Positioning System crustal thickness elastic lithosphere thickness mantle viscosity Antarctica post glacial rebound seismic tomography ice sheet thickness West Antarctic Rift System Transantarctic Mountains Marie Byrd Land Ellsworth Land Antarctic Peninsula East Antarctica simulated annealing Thesis 2012 ftuvicpubl 2022-05-19T06:10:38Z Glacial isostatic adjustment (GIA) is the process by which the solid Earth responds to past and present-day changes in glaciers, ice caps, and ice sheets. This thesis focuses on vertical crustal motion of the Earth caused by GIA, which is influenced by several factors including lithosphere thickness, mantle viscosity profile, and changes to the thickness and extent of surface ice. The viscosity of the mantle beneath Antarctica is a poorly constrained quantity due to the rarity of relative sea-level and heat flow observations. Other methods for obtaining a better-constrained mantle viscosity model must be investigated to obtain more accurate GIA model predictions. The first section of this study uses seismic wave tomography to determine mantle viscosity. By calculating the deviation of the P- and S-wave velocities relative to a reference Earth model (PREM), the viscosity can be determined. For Antarctica mantle viscosities obtained from S20A (Ekstrom and Dziewonski, 1998) seismic tomography in the asthenosphere range from 1016 Pa∙s to 1023 Pa∙s, with smaller viscosities beneath West Antarctica and higher viscosities beneath East Antarctica. This agrees with viscosity expectations based on findings from the Basin and Range area of North America, which is an analogue to the West Antarctic Rift System. Section two compares bedrock elevations in Antarctica to crustal thicknesses, to infer mantle temperatures and draw conclusions about mantle viscosity. Data from CRUST 2.0 (Bassin et al., 2000), BEDMAP (Lythe and Vaughan, 2001) and specific studies of crustal thickness in Antarctica were examined. It was found that the regions of Antarctica that are expected to have low viscosities agree with the hot mantle trend found by Hyndman (2010) while the regions expected to have high viscosity are in better agreement with the trend for cold mantle. Bevis et al. (2009) described new GPS observations of crustal uplift in Antarctica and compared the results to GIA model predictions, including IJ05 (Ivins and James, 2005). Here, ... Thesis Antarc* Antarctic Antarctic Peninsula Antarctica East Antarctica Ice Sheet Marie Byrd Land West Antarctica University of Victoria (Canada): UVicDSpace Antarctic Antarctic Peninsula Byrd East Antarctica Ellsworth Land ENVELOPE(-85.000,-85.000,-75.000,-75.000) Marie Byrd Land ENVELOPE(-130.000,-130.000,-78.000,-78.000) Transantarctic Mountains West Antarctica |
institution |
Open Polar |
collection |
University of Victoria (Canada): UVicDSpace |
op_collection_id |
ftuvicpubl |
language |
English |
topic |
glacial isostatic adjustment Global Positioning System crustal thickness elastic lithosphere thickness mantle viscosity Antarctica post glacial rebound seismic tomography ice sheet thickness West Antarctic Rift System Transantarctic Mountains Marie Byrd Land Ellsworth Land Antarctic Peninsula East Antarctica simulated annealing |
spellingShingle |
glacial isostatic adjustment Global Positioning System crustal thickness elastic lithosphere thickness mantle viscosity Antarctica post glacial rebound seismic tomography ice sheet thickness West Antarctic Rift System Transantarctic Mountains Marie Byrd Land Ellsworth Land Antarctic Peninsula East Antarctica simulated annealing Darlington, Andrea Geophysical constraints on mantle viscosity and its influence on Antarctic glacial isostatic adjustment |
topic_facet |
glacial isostatic adjustment Global Positioning System crustal thickness elastic lithosphere thickness mantle viscosity Antarctica post glacial rebound seismic tomography ice sheet thickness West Antarctic Rift System Transantarctic Mountains Marie Byrd Land Ellsworth Land Antarctic Peninsula East Antarctica simulated annealing |
description |
Glacial isostatic adjustment (GIA) is the process by which the solid Earth responds to past and present-day changes in glaciers, ice caps, and ice sheets. This thesis focuses on vertical crustal motion of the Earth caused by GIA, which is influenced by several factors including lithosphere thickness, mantle viscosity profile, and changes to the thickness and extent of surface ice. The viscosity of the mantle beneath Antarctica is a poorly constrained quantity due to the rarity of relative sea-level and heat flow observations. Other methods for obtaining a better-constrained mantle viscosity model must be investigated to obtain more accurate GIA model predictions. The first section of this study uses seismic wave tomography to determine mantle viscosity. By calculating the deviation of the P- and S-wave velocities relative to a reference Earth model (PREM), the viscosity can be determined. For Antarctica mantle viscosities obtained from S20A (Ekstrom and Dziewonski, 1998) seismic tomography in the asthenosphere range from 1016 Pa∙s to 1023 Pa∙s, with smaller viscosities beneath West Antarctica and higher viscosities beneath East Antarctica. This agrees with viscosity expectations based on findings from the Basin and Range area of North America, which is an analogue to the West Antarctic Rift System. Section two compares bedrock elevations in Antarctica to crustal thicknesses, to infer mantle temperatures and draw conclusions about mantle viscosity. Data from CRUST 2.0 (Bassin et al., 2000), BEDMAP (Lythe and Vaughan, 2001) and specific studies of crustal thickness in Antarctica were examined. It was found that the regions of Antarctica that are expected to have low viscosities agree with the hot mantle trend found by Hyndman (2010) while the regions expected to have high viscosity are in better agreement with the trend for cold mantle. Bevis et al. (2009) described new GPS observations of crustal uplift in Antarctica and compared the results to GIA model predictions, including IJ05 (Ivins and James, 2005). Here, ... |
author2 |
James, Thomas Sinclair Spence, George D. |
format |
Thesis |
author |
Darlington, Andrea |
author_facet |
Darlington, Andrea |
author_sort |
Darlington, Andrea |
title |
Geophysical constraints on mantle viscosity and its influence on Antarctic glacial isostatic adjustment |
title_short |
Geophysical constraints on mantle viscosity and its influence on Antarctic glacial isostatic adjustment |
title_full |
Geophysical constraints on mantle viscosity and its influence on Antarctic glacial isostatic adjustment |
title_fullStr |
Geophysical constraints on mantle viscosity and its influence on Antarctic glacial isostatic adjustment |
title_full_unstemmed |
Geophysical constraints on mantle viscosity and its influence on Antarctic glacial isostatic adjustment |
title_sort |
geophysical constraints on mantle viscosity and its influence on antarctic glacial isostatic adjustment |
publishDate |
2012 |
url |
http://hdl.handle.net/1828/4001 |
long_lat |
ENVELOPE(-85.000,-85.000,-75.000,-75.000) ENVELOPE(-130.000,-130.000,-78.000,-78.000) |
geographic |
Antarctic Antarctic Peninsula Byrd East Antarctica Ellsworth Land Marie Byrd Land Transantarctic Mountains West Antarctica |
geographic_facet |
Antarctic Antarctic Peninsula Byrd East Antarctica Ellsworth Land Marie Byrd Land Transantarctic Mountains West Antarctica |
genre |
Antarc* Antarctic Antarctic Peninsula Antarctica East Antarctica Ice Sheet Marie Byrd Land West Antarctica |
genre_facet |
Antarc* Antarctic Antarctic Peninsula Antarctica East Antarctica Ice Sheet Marie Byrd Land West Antarctica |
op_relation |
http://hdl.handle.net/1828/4001 |
op_rights |
Available to the World Wide Web |
_version_ |
1766273405142695936 |