Shear Wave Splitting Across Antarctica: Implications for Upper Mantle Seismic Anisotropy
We examine upper mantle anisotropy across the Antarctic continent using 102 new shear wave splitting measurements obtained from teleseismic SKS, SKKS, and PKS phases combined with 107 previously published results. For the new measurements, an eigenvalue technique is used to estimate the fast polariz...
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ftcwashingtonuni:oai:digitalcommons.cwu.edu:cotsfac-1826 2023-05-15T13:47:32+02:00 Shear Wave Splitting Across Antarctica: Implications for Upper Mantle Seismic Anisotropy Lucas, Erica M. Nyblade, Andrew A. Accardo, Natalie J. Lloyd, Andrew J. Wiens, Douglas A. Aster, Richard C. Wilson, Terry J. Dalziel, Ian W. Stuart, Graham W. O'Donnell, John Paul Winberry, J. Paul Huerta, Audrey D. Antarctica 2022-04-01T07:00:00Z https://digitalcommons.cwu.edu/cotsfac/826 English eng ScholarWorks@CWU https://digitalcommons.cwu.edu/cotsfac/826 ezp.lib.cwu.edu/login?url=http://dx.doi.org/10.1029/2021JB023325 © 2022. American Geophysical Union. All Faculty Scholarship for the College of the Sciences shear wave splitting anisotropy Antarctica upper mantle Geochemistry Geomorphology Geophysics and Seismology Tectonics and Structure text 2022 ftcwashingtonuni 2022-10-20T20:38:02Z We examine upper mantle anisotropy across the Antarctic continent using 102 new shear wave splitting measurements obtained from teleseismic SKS, SKKS, and PKS phases combined with 107 previously published results. For the new measurements, an eigenvalue technique is used to estimate the fast polarization direction and delay time for each phase arrival, and high-quality measurements are stacked to determine the best-fit splitting parameters at each seismic station. The ensemble of splitting measurements shows largely NE-SW-oriented fast polarization directions across Antarctica, with a broadly clockwise rotation in polarization directions evident moving from west to east across the continent. Although the first-order pattern of NE-SW-oriented polarization directions is suggestive of a single plate-wide source of anisotropy, we argue the observed pattern of anisotropy more likely arises from regionally variable contributions of both lithospheric and sub-lithospheric mantle sources. Anisotropy observed in the interior of East Antarctica, a region underlain by thick lithosphere, can be attributed to relict fabrics associated with Precambrian tectonism. In contrast, anisotropy observed in coastal East Antarctica, the Transantarctic Mountains (TAM), and across much of West Antarctica likely reflects both lithospheric and sub-lithospheric mantle fabrics. While sub-lithospheric mantle fabrics are best associated with either plate motion-induced asthenospheric flow or small-scale convection, lithospheric mantle fabrics in coastal East Antarctica, the TAM, and West Antarctica generally reflect Jurassic—Cenozoic tectonic activity. Text Antarc* Antarctic Antarctica East Antarctica West Antarctica Central Washington University: ScholarWorks Antarctic East Antarctica The Antarctic Transantarctic Mountains West Antarctica Journal of Geophysical Research: Solid Earth 127 4 |
institution |
Open Polar |
collection |
Central Washington University: ScholarWorks |
op_collection_id |
ftcwashingtonuni |
language |
English |
topic |
shear wave splitting anisotropy Antarctica upper mantle Geochemistry Geomorphology Geophysics and Seismology Tectonics and Structure |
spellingShingle |
shear wave splitting anisotropy Antarctica upper mantle Geochemistry Geomorphology Geophysics and Seismology Tectonics and Structure Lucas, Erica M. Nyblade, Andrew A. Accardo, Natalie J. Lloyd, Andrew J. Wiens, Douglas A. Aster, Richard C. Wilson, Terry J. Dalziel, Ian W. Stuart, Graham W. O'Donnell, John Paul Winberry, J. Paul Huerta, Audrey D. Shear Wave Splitting Across Antarctica: Implications for Upper Mantle Seismic Anisotropy |
topic_facet |
shear wave splitting anisotropy Antarctica upper mantle Geochemistry Geomorphology Geophysics and Seismology Tectonics and Structure |
description |
We examine upper mantle anisotropy across the Antarctic continent using 102 new shear wave splitting measurements obtained from teleseismic SKS, SKKS, and PKS phases combined with 107 previously published results. For the new measurements, an eigenvalue technique is used to estimate the fast polarization direction and delay time for each phase arrival, and high-quality measurements are stacked to determine the best-fit splitting parameters at each seismic station. The ensemble of splitting measurements shows largely NE-SW-oriented fast polarization directions across Antarctica, with a broadly clockwise rotation in polarization directions evident moving from west to east across the continent. Although the first-order pattern of NE-SW-oriented polarization directions is suggestive of a single plate-wide source of anisotropy, we argue the observed pattern of anisotropy more likely arises from regionally variable contributions of both lithospheric and sub-lithospheric mantle sources. Anisotropy observed in the interior of East Antarctica, a region underlain by thick lithosphere, can be attributed to relict fabrics associated with Precambrian tectonism. In contrast, anisotropy observed in coastal East Antarctica, the Transantarctic Mountains (TAM), and across much of West Antarctica likely reflects both lithospheric and sub-lithospheric mantle fabrics. While sub-lithospheric mantle fabrics are best associated with either plate motion-induced asthenospheric flow or small-scale convection, lithospheric mantle fabrics in coastal East Antarctica, the TAM, and West Antarctica generally reflect Jurassic—Cenozoic tectonic activity. |
format |
Text |
author |
Lucas, Erica M. Nyblade, Andrew A. Accardo, Natalie J. Lloyd, Andrew J. Wiens, Douglas A. Aster, Richard C. Wilson, Terry J. Dalziel, Ian W. Stuart, Graham W. O'Donnell, John Paul Winberry, J. Paul Huerta, Audrey D. |
author_facet |
Lucas, Erica M. Nyblade, Andrew A. Accardo, Natalie J. Lloyd, Andrew J. Wiens, Douglas A. Aster, Richard C. Wilson, Terry J. Dalziel, Ian W. Stuart, Graham W. O'Donnell, John Paul Winberry, J. Paul Huerta, Audrey D. |
author_sort |
Lucas, Erica M. |
title |
Shear Wave Splitting Across Antarctica: Implications for Upper Mantle Seismic Anisotropy |
title_short |
Shear Wave Splitting Across Antarctica: Implications for Upper Mantle Seismic Anisotropy |
title_full |
Shear Wave Splitting Across Antarctica: Implications for Upper Mantle Seismic Anisotropy |
title_fullStr |
Shear Wave Splitting Across Antarctica: Implications for Upper Mantle Seismic Anisotropy |
title_full_unstemmed |
Shear Wave Splitting Across Antarctica: Implications for Upper Mantle Seismic Anisotropy |
title_sort |
shear wave splitting across antarctica: implications for upper mantle seismic anisotropy |
publisher |
ScholarWorks@CWU |
publishDate |
2022 |
url |
https://digitalcommons.cwu.edu/cotsfac/826 |
op_coverage |
Antarctica |
geographic |
Antarctic East Antarctica The Antarctic Transantarctic Mountains West Antarctica |
geographic_facet |
Antarctic East Antarctica The Antarctic Transantarctic Mountains West Antarctica |
genre |
Antarc* Antarctic Antarctica East Antarctica West Antarctica |
genre_facet |
Antarc* Antarctic Antarctica East Antarctica West Antarctica |
op_source |
All Faculty Scholarship for the College of the Sciences |
op_relation |
https://digitalcommons.cwu.edu/cotsfac/826 ezp.lib.cwu.edu/login?url=http://dx.doi.org/10.1029/2021JB023325 |
op_rights |
© 2022. American Geophysical Union. |
container_title |
Journal of Geophysical Research: Solid Earth |
container_volume |
127 |
container_issue |
4 |
_version_ |
1766247277397016576 |