Magnetic anisotropy and debris-dependent rheological heterogeneity within stratified basal ice
Abstract Basal ice of glaciers and ice sheets frequently contains a well-developed stratification of distinct, semi-continuous, alternating layers of debris-poor and debris-rich ice. Here, the nature and distribution of shear within stratified basal ice are assessed through the anisotropy of magneti...
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Cambridge University Press (CUP)
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Online Access: | http://dx.doi.org/10.1017/jog.2019.51 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143019000510 |
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crcambridgeupr:10.1017/jog.2019.51 2024-03-03T08:44:35+00:00 Magnetic anisotropy and debris-dependent rheological heterogeneity within stratified basal ice Hopkins, Nathan R. Evenson, Edward B. Bilardello, Dario Alley, Richard B. Berti, Claudio Kodama, Kenneth P. 2019 http://dx.doi.org/10.1017/jog.2019.51 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143019000510 en eng Cambridge University Press (CUP) http://creativecommons.org/licenses/by/4.0/ Journal of Glaciology volume 65, issue 253, page 770-779 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 2019 crcambridgeupr https://doi.org/10.1017/jog.2019.51 2024-02-08T08:32:05Z Abstract Basal ice of glaciers and ice sheets frequently contains a well-developed stratification of distinct, semi-continuous, alternating layers of debris-poor and debris-rich ice. Here, the nature and distribution of shear within stratified basal ice are assessed through the anisotropy of magnetic susceptibility (AMS) of samples collected from Matanuska Glacier, Alaska. Generally, the AMS reveals consistent moderate-to-strong fabrics reflecting simple shear in the direction of ice flow; however, AMS is also dependent upon debris content and morphology. While sample anisotropy is statistically similar throughout the sampled section, debris-rich basal ice composed of semi-continuous mm-scale layers (the stratified facies ) possesses well-defined triaxial to oblate fabrics reflecting shear in the direction of ice flow, whereas debris-poor ice containing mm-scale star-shaped silt aggregates (the suspended facies ) possesses nearly isotropic fabrics. Thus, deformation within the stratified basal ice appears concentrated in debris-rich layers, likely the result of decreased crystal size and greater availability of unfrozen water associated with high debris content. These results suggest that variations in debris-content over small spatial scales influence ice rheology and deformation in the basal zone. Article in Journal/Newspaper glacier glaciers Journal of Glaciology Alaska Cambridge University Press Journal of Glaciology 65 253 770 779 |
institution |
Open Polar |
collection |
Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
spellingShingle |
Earth-Surface Processes Hopkins, Nathan R. Evenson, Edward B. Bilardello, Dario Alley, Richard B. Berti, Claudio Kodama, Kenneth P. Magnetic anisotropy and debris-dependent rheological heterogeneity within stratified basal ice |
topic_facet |
Earth-Surface Processes |
description |
Abstract Basal ice of glaciers and ice sheets frequently contains a well-developed stratification of distinct, semi-continuous, alternating layers of debris-poor and debris-rich ice. Here, the nature and distribution of shear within stratified basal ice are assessed through the anisotropy of magnetic susceptibility (AMS) of samples collected from Matanuska Glacier, Alaska. Generally, the AMS reveals consistent moderate-to-strong fabrics reflecting simple shear in the direction of ice flow; however, AMS is also dependent upon debris content and morphology. While sample anisotropy is statistically similar throughout the sampled section, debris-rich basal ice composed of semi-continuous mm-scale layers (the stratified facies ) possesses well-defined triaxial to oblate fabrics reflecting shear in the direction of ice flow, whereas debris-poor ice containing mm-scale star-shaped silt aggregates (the suspended facies ) possesses nearly isotropic fabrics. Thus, deformation within the stratified basal ice appears concentrated in debris-rich layers, likely the result of decreased crystal size and greater availability of unfrozen water associated with high debris content. These results suggest that variations in debris-content over small spatial scales influence ice rheology and deformation in the basal zone. |
format |
Article in Journal/Newspaper |
author |
Hopkins, Nathan R. Evenson, Edward B. Bilardello, Dario Alley, Richard B. Berti, Claudio Kodama, Kenneth P. |
author_facet |
Hopkins, Nathan R. Evenson, Edward B. Bilardello, Dario Alley, Richard B. Berti, Claudio Kodama, Kenneth P. |
author_sort |
Hopkins, Nathan R. |
title |
Magnetic anisotropy and debris-dependent rheological heterogeneity within stratified basal ice |
title_short |
Magnetic anisotropy and debris-dependent rheological heterogeneity within stratified basal ice |
title_full |
Magnetic anisotropy and debris-dependent rheological heterogeneity within stratified basal ice |
title_fullStr |
Magnetic anisotropy and debris-dependent rheological heterogeneity within stratified basal ice |
title_full_unstemmed |
Magnetic anisotropy and debris-dependent rheological heterogeneity within stratified basal ice |
title_sort |
magnetic anisotropy and debris-dependent rheological heterogeneity within stratified basal ice |
publisher |
Cambridge University Press (CUP) |
publishDate |
2019 |
url |
http://dx.doi.org/10.1017/jog.2019.51 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143019000510 |
genre |
glacier glaciers Journal of Glaciology Alaska |
genre_facet |
glacier glaciers Journal of Glaciology Alaska |
op_source |
Journal of Glaciology volume 65, issue 253, page 770-779 ISSN 0022-1430 1727-5652 |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1017/jog.2019.51 |
container_title |
Journal of Glaciology |
container_volume |
65 |
container_issue |
253 |
container_start_page |
770 |
op_container_end_page |
779 |
_version_ |
1792500076292079616 |