Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica
We use high resolution, ground-based observations of ice displacement to investigate ice deformation across the floating left-lateral shear margin of Priestley Glacier, Terra Nova Bay, Antarctica. Bare ice conditions allow us to fix survey marks directly to the glacier surface. A combination of cont...
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crfrontiers:10.3389/feart.2022.828313 2024-02-11T09:57:44+01:00 Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica Still, Holly Hulbe, Christina Forbes, Martin Prior, David J. Bowman, M. Hamish Boucinhas, Bia Craw, Lisa Kim, Daeyeong Lutz, Franz Mulvaney, Robert Thomas, Rilee E. 2022 http://dx.doi.org/10.3389/feart.2022.828313 https://www.frontiersin.org/articles/10.3389/feart.2022.828313/full unknown Frontiers Media SA https://creativecommons.org/licenses/by/4.0/ Frontiers in Earth Science volume 10 ISSN 2296-6463 General Earth and Planetary Sciences journal-article 2022 crfrontiers https://doi.org/10.3389/feart.2022.828313 2024-01-26T09:57:54Z We use high resolution, ground-based observations of ice displacement to investigate ice deformation across the floating left-lateral shear margin of Priestley Glacier, Terra Nova Bay, Antarctica. Bare ice conditions allow us to fix survey marks directly to the glacier surface. A combination of continuous positioning of a local reference mark, and repeat positioning of a network of 33 stakes installed across a 2 km width of the shear margin are used to quantify shear strain rates and the ice response to tidal forcing over an 18-day period. Along-flow velocity observed at a continuous Global Navigation Satellite Systems (GNSS) station within the network varies by up to ∼30% of the mean speed (±28 m a −1 ) over diurnal tidal cycles, with faster flow during the falling tide and slower flow during the rising tide. Long-term deformation in the margin approximates simple shear with a small component of flow-parallel shortening. At shorter timescales, precise optical techniques allow high-resolution observations of across-flow bending in response to the ocean tide, including across-flow strains on the order of 10 –5 . An elastodynamic model informed by the field observations is used to simulate the across-flow motion and deformation. Flexure is concentrated in the shear margin, such that a non-homogeneous elastic modulus is implied to best account for the combined observations. The combined pattern of ice displacement and ice strain also depends on the extent of coupling between the ice and valley sidewall. These conclusions suggest that investigations of elastic properties made using vertical ice motion, but neglecting horizontal displacement and surface strain, will lead to incorrect conclusions about the elastic properties of ice and potentially over-simplified assumptions about the sidewall boundary condition. Article in Journal/Newspaper Antarc* Antarctica Priestley Glacier Frontiers (Publisher) Priestley ENVELOPE(161.883,161.883,-75.183,-75.183) Priestley Glacier ENVELOPE(163.367,163.367,-74.333,-74.333) Terra Nova Bay Frontiers in Earth Science 10 |
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topic |
General Earth and Planetary Sciences |
spellingShingle |
General Earth and Planetary Sciences Still, Holly Hulbe, Christina Forbes, Martin Prior, David J. Bowman, M. Hamish Boucinhas, Bia Craw, Lisa Kim, Daeyeong Lutz, Franz Mulvaney, Robert Thomas, Rilee E. Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica |
topic_facet |
General Earth and Planetary Sciences |
description |
We use high resolution, ground-based observations of ice displacement to investigate ice deformation across the floating left-lateral shear margin of Priestley Glacier, Terra Nova Bay, Antarctica. Bare ice conditions allow us to fix survey marks directly to the glacier surface. A combination of continuous positioning of a local reference mark, and repeat positioning of a network of 33 stakes installed across a 2 km width of the shear margin are used to quantify shear strain rates and the ice response to tidal forcing over an 18-day period. Along-flow velocity observed at a continuous Global Navigation Satellite Systems (GNSS) station within the network varies by up to ∼30% of the mean speed (±28 m a −1 ) over diurnal tidal cycles, with faster flow during the falling tide and slower flow during the rising tide. Long-term deformation in the margin approximates simple shear with a small component of flow-parallel shortening. At shorter timescales, precise optical techniques allow high-resolution observations of across-flow bending in response to the ocean tide, including across-flow strains on the order of 10 –5 . An elastodynamic model informed by the field observations is used to simulate the across-flow motion and deformation. Flexure is concentrated in the shear margin, such that a non-homogeneous elastic modulus is implied to best account for the combined observations. The combined pattern of ice displacement and ice strain also depends on the extent of coupling between the ice and valley sidewall. These conclusions suggest that investigations of elastic properties made using vertical ice motion, but neglecting horizontal displacement and surface strain, will lead to incorrect conclusions about the elastic properties of ice and potentially over-simplified assumptions about the sidewall boundary condition. |
format |
Article in Journal/Newspaper |
author |
Still, Holly Hulbe, Christina Forbes, Martin Prior, David J. Bowman, M. Hamish Boucinhas, Bia Craw, Lisa Kim, Daeyeong Lutz, Franz Mulvaney, Robert Thomas, Rilee E. |
author_facet |
Still, Holly Hulbe, Christina Forbes, Martin Prior, David J. Bowman, M. Hamish Boucinhas, Bia Craw, Lisa Kim, Daeyeong Lutz, Franz Mulvaney, Robert Thomas, Rilee E. |
author_sort |
Still, Holly |
title |
Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica |
title_short |
Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica |
title_full |
Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica |
title_fullStr |
Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica |
title_full_unstemmed |
Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica |
title_sort |
tidal modulation of a lateral shear margin: priestley glacier, antarctica |
publisher |
Frontiers Media SA |
publishDate |
2022 |
url |
http://dx.doi.org/10.3389/feart.2022.828313 https://www.frontiersin.org/articles/10.3389/feart.2022.828313/full |
long_lat |
ENVELOPE(161.883,161.883,-75.183,-75.183) ENVELOPE(163.367,163.367,-74.333,-74.333) |
geographic |
Priestley Priestley Glacier Terra Nova Bay |
geographic_facet |
Priestley Priestley Glacier Terra Nova Bay |
genre |
Antarc* Antarctica Priestley Glacier |
genre_facet |
Antarc* Antarctica Priestley Glacier |
op_source |
Frontiers in Earth Science volume 10 ISSN 2296-6463 |
op_rights |
https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.3389/feart.2022.828313 |
container_title |
Frontiers in Earth Science |
container_volume |
10 |
_version_ |
1790593279827378176 |