Sonic methods for measuring crystal orientation fabric in ice, and results from the West Antarctic ice sheet (WAIS) Divide
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...
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Cambridge University Press
2017
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ftdoajarticles:oai:doaj.org/article:12af70a67c97417dbef04fed621360ba 2023-05-15T14:02:53+02:00 Sonic methods for measuring crystal orientation fabric in ice, and results from the West Antarctic ice sheet (WAIS) Divide DAN KLUSKIEWICZ EDWIN D. WADDINGTON SRIDHAR ANANDAKRISHNAN DONALD E. VOIGT KENICHI MATSUOKA MICHAEL P. McCARTHY 2017-08-01T00:00:00Z https://doi.org/10.1017/jog.2017.20 https://doaj.org/article/12af70a67c97417dbef04fed621360ba EN eng Cambridge University Press https://www.cambridge.org/core/product/identifier/S002214301700020X/type/journal_article https://doaj.org/toc/0022-1430 https://doaj.org/toc/1727-5652 doi:10.1017/jog.2017.20 0022-1430 1727-5652 https://doaj.org/article/12af70a67c97417dbef04fed621360ba Journal of Glaciology, Vol 63, Pp 603-617 (2017) anisotropy crystal fabric ice lattice sonic Environmental sciences GE1-350 Meteorology. Climatology QC851-999 article 2017 ftdoajarticles https://doi.org/10.1017/jog.2017.20 2023-03-12T01:30:59Z 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 Directory of Open Access Journals: DOAJ Articles Antarctic West Antarctic Ice Sheet Journal of Glaciology 63 240 603 617 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
anisotropy crystal fabric ice lattice sonic Environmental sciences GE1-350 Meteorology. Climatology QC851-999 |
spellingShingle |
anisotropy crystal fabric ice lattice sonic Environmental sciences GE1-350 Meteorology. Climatology QC851-999 DAN KLUSKIEWICZ EDWIN D. WADDINGTON SRIDHAR ANANDAKRISHNAN DONALD E. VOIGT KENICHI MATSUOKA MICHAEL P. McCARTHY Sonic methods for measuring crystal orientation fabric in ice, and results from the West Antarctic ice sheet (WAIS) Divide |
topic_facet |
anisotropy crystal fabric ice lattice sonic Environmental sciences GE1-350 Meteorology. Climatology QC851-999 |
description |
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 |
DAN KLUSKIEWICZ EDWIN D. WADDINGTON SRIDHAR ANANDAKRISHNAN DONALD E. VOIGT KENICHI MATSUOKA MICHAEL P. McCARTHY |
author_facet |
DAN KLUSKIEWICZ EDWIN D. WADDINGTON SRIDHAR ANANDAKRISHNAN DONALD E. VOIGT KENICHI MATSUOKA MICHAEL P. McCARTHY |
author_sort |
DAN KLUSKIEWICZ |
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 |
publishDate |
2017 |
url |
https://doi.org/10.1017/jog.2017.20 https://doaj.org/article/12af70a67c97417dbef04fed621360ba |
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, Vol 63, Pp 603-617 (2017) |
op_relation |
https://www.cambridge.org/core/product/identifier/S002214301700020X/type/journal_article https://doaj.org/toc/0022-1430 https://doaj.org/toc/1727-5652 doi:10.1017/jog.2017.20 0022-1430 1727-5652 https://doaj.org/article/12af70a67c97417dbef04fed621360ba |
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_ |
1766273325821067264 |