Sonic methods for measuring crystal orientation fabric in ice, and results from the West Antarctic ice sheet (WAIS) Divide
ABSTRACT We describe methods for measuring crystal orientation fabric with sonic waves in an ice core borehole, with special attention paid to vertical-girdle fabrics that are prevalent at the WAIS Divide. The speed of vertically propagating compressional waves in ice is influenced by vertical clust...
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crcambridgeupr:10.1017/jog.2017.20 2024-03-03T08:39:17+00:00 Sonic methods for measuring crystal orientation fabric in ice, and results from the West Antarctic ice sheet (WAIS) Divide KLUSKIEWICZ, DAN WADDINGTON, EDWIN D. ANANDAKRISHNAN, SRIDHAR VOIGT, DONALD E. MATSUOKA, KENICHI McCARTHY, MICHAEL P. 2017 http://dx.doi.org/10.1017/jog.2017.20 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214301700020X en eng Cambridge University Press (CUP) http://creativecommons.org/licenses/by/4.0/ Journal of Glaciology volume 63, issue 240, page 603-617 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 2017 crcambridgeupr https://doi.org/10.1017/jog.2017.20 2024-02-08T08:45:37Z ABSTRACT We describe methods for measuring crystal orientation fabric with sonic waves in an ice core borehole, with special attention paid to vertical-girdle fabrics that are prevalent at the WAIS Divide. The speed of vertically propagating compressional waves in ice is influenced by vertical clustering of the ice crystal c -axes. Shear-wave speeds – particularly the speed separation between fast and slow shear polarizations – are sensitive to azimuthal anisotropy. Sonic data from the WAIS Divide complement thin-section measurements of fabric. Thin sections show a steady transition to strong girdle fabrics in the upper 2000 m of ice, followed by a transition to vertical-pole fabrics below 2500 m depth. Compressional-wave sonic data are inconclusive in the upper ice, due to noise, as well as the method's inherent insensitivity to girdle fabrics. Compared with available thin sections, sonic data provide better resolution of the transition to pole fabrics below 2500 m, notably including an abrupt increase in vertical clustering near 3000 m. Our compressional-wave measurements resolve fabric changes occurring over depth ranges of a few meters that cannot be inferred from available thin sections, but are sensitive only to zenithal anisotropy. Future logging tools should be designed to measure shear waves in addition to compressional waves, especially for logging in regions where ice flow patterns favor the development of girdle fabrics. Article in Journal/Newspaper Antarc* Antarctic ice core Ice Sheet Journal of Glaciology Cambridge University Press Antarctic West Antarctic Ice Sheet Journal of Glaciology 63 240 603 617 |
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Open Polar |
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Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
spellingShingle |
Earth-Surface Processes KLUSKIEWICZ, DAN WADDINGTON, EDWIN D. ANANDAKRISHNAN, SRIDHAR VOIGT, DONALD E. MATSUOKA, KENICHI McCARTHY, MICHAEL P. Sonic methods for measuring crystal orientation fabric in ice, and results from the West Antarctic ice sheet (WAIS) Divide |
topic_facet |
Earth-Surface Processes |
description |
ABSTRACT We describe methods for measuring crystal orientation fabric with sonic waves in an ice core borehole, with special attention paid to vertical-girdle fabrics that are prevalent at the WAIS Divide. The speed of vertically propagating compressional waves in ice is influenced by vertical clustering of the ice crystal c -axes. Shear-wave speeds – particularly the speed separation between fast and slow shear polarizations – are sensitive to azimuthal anisotropy. Sonic data from the WAIS Divide complement thin-section measurements of fabric. Thin sections show a steady transition to strong girdle fabrics in the upper 2000 m of ice, followed by a transition to vertical-pole fabrics below 2500 m depth. Compressional-wave sonic data are inconclusive in the upper ice, due to noise, as well as the method's inherent insensitivity to girdle fabrics. Compared with available thin sections, sonic data provide better resolution of the transition to pole fabrics below 2500 m, notably including an abrupt increase in vertical clustering near 3000 m. Our compressional-wave measurements resolve fabric changes occurring over depth ranges of a few meters that cannot be inferred from available thin sections, but are sensitive only to zenithal anisotropy. Future logging tools should be designed to measure shear waves in addition to compressional waves, especially for logging in regions where ice flow patterns favor the development of girdle fabrics. |
format |
Article in Journal/Newspaper |
author |
KLUSKIEWICZ, DAN WADDINGTON, EDWIN D. ANANDAKRISHNAN, SRIDHAR VOIGT, DONALD E. MATSUOKA, KENICHI McCARTHY, MICHAEL P. |
author_facet |
KLUSKIEWICZ, DAN WADDINGTON, EDWIN D. ANANDAKRISHNAN, SRIDHAR VOIGT, DONALD E. MATSUOKA, KENICHI McCARTHY, MICHAEL P. |
author_sort |
KLUSKIEWICZ, DAN |
title |
Sonic methods for measuring crystal orientation fabric in ice, and results from the West Antarctic ice sheet (WAIS) Divide |
title_short |
Sonic methods for measuring crystal orientation fabric in ice, and results from the West Antarctic ice sheet (WAIS) Divide |
title_full |
Sonic methods for measuring crystal orientation fabric in ice, and results from the West Antarctic ice sheet (WAIS) Divide |
title_fullStr |
Sonic methods for measuring crystal orientation fabric in ice, and results from the West Antarctic ice sheet (WAIS) Divide |
title_full_unstemmed |
Sonic methods for measuring crystal orientation fabric in ice, and results from the West Antarctic ice sheet (WAIS) Divide |
title_sort |
sonic methods for measuring crystal orientation fabric in ice, and results from the west antarctic ice sheet (wais) divide |
publisher |
Cambridge University Press (CUP) |
publishDate |
2017 |
url |
http://dx.doi.org/10.1017/jog.2017.20 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214301700020X |
geographic |
Antarctic West Antarctic Ice Sheet |
geographic_facet |
Antarctic West Antarctic Ice Sheet |
genre |
Antarc* Antarctic ice core Ice Sheet Journal of Glaciology |
genre_facet |
Antarc* Antarctic ice core Ice Sheet Journal of Glaciology |
op_source |
Journal of Glaciology volume 63, issue 240, page 603-617 ISSN 0022-1430 1727-5652 |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1017/jog.2017.20 |
container_title |
Journal of Glaciology |
container_volume |
63 |
container_issue |
240 |
container_start_page |
603 |
op_container_end_page |
617 |
_version_ |
1792494731078402048 |