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Processes controlling the downstream evolution of ice rheology in glacier shear margins: case study on Rutford Ice Stream, West Antarctica

Minchew, Brent M. and Meyer, Colin R. and Robel, Alexander A. and Gudmundsson, G. Hilmar and Simons, Mark (2018) Processes controlling the downstream evolution of ice rheology in glacier shear margins: case study on Rutford Ice Stream, West Antarctica. Journal of Glaciology, 64 (246). pp. 583-594. ISSN 0022-1430. https://resolver.caltech.edu/CaltechAUTHORS:20180912-135248522

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Abstract

Ice rheology governs how glaciers flow and respond to environmental change. The rheology of glacier ice evolves in response to a variety of mechanisms, including damage, heating, melting and the development of crystalline fabric. The relative contributions of these rheological mechanisms are not well understood. Using remotely sensed data and physical models, we decouple the influence of each of the aforementioned mechanisms along the margins of Rutford Ice Stream, a laterally confined outlet glacier in West Antarctica. We show that fabric is an important control on ice rheology in the shear margins, with an inferred softening effect consistent with a single-maximum fabric. Fabric evolves to steady state near the onset of streaming flow, and ice progressively softens downstream almost exclusively due to shear heating. The rate of heating is sensitive to local shear strain rates, which respond to local changes in bed topography as ice is squeezed through the basal trough. The impact of shear heating on the downstream evolution of ice rheology in a laterally confined glacier suggests that the thermoviscous feedback – wherein faster ice flow leads to higher rates of shear heating, further softening the ice – is a fundamental control on glacier dynamics.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1017/jog.2018.47DOIArticle
ORCID:
AuthorORCID
Minchew, Brent M.0000-0002-5991-3926
Robel, Alexander A.0000-0003-4520-0105
Gudmundsson, G. Hilmar0000-0003-4236-5369
Simons, Mark0000-0003-1412-6395
Additional Information:© The Author(s) 2018. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. Published online: 07 June 2018. We thank Carlos Martin, Robert Arthern, Jenny Suckale, Cooper Elsworth and James Rice for insightful conversations. We also thank two anonymous reviewers for helpful comments. B.M.M. was funded by an NSF Earth Sciences Postdoctoral Fellowship award EAR-1452587. C.R.M. was supported by an NSF Graduate Research Fellowship, award DGE-1144152 and a David Crighton Fellowship. A.A.R. was funded through a NOAA Climate & Global Change Postdoctoral Fellowship and the Caltech Stanback Postdoctoral Fellowship.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSFEAR-1452587
NSF Graduate Research FellowshipDGE-1144152
David Crighton FellowshipUNSPECIFIED
National Oceanic and Atmospheric Administration (NOAA)UNSPECIFIED
Coco and Foster Stanback Postdoctoral Fellowship in Global Environmental ScienceUNSPECIFIED
Subject Keywords:Anisotropic ice flow, Antarctic glaciology, glacial rheology, glacier flow, ice rheology
Issue or Number:246
Record Number:CaltechAUTHORS:20180912-135248522
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180912-135248522
Official Citation:MINCHEW, B., MEYER, C., ROBEL, A., GUDMUNDSSON, G., & SIMONS, M. (2018). Processes controlling the downstream evolution of ice rheology in glacier shear margins: Case study on Rutford Ice Stream, West Antarctica. Journal of Glaciology, 64(246), 583-594. doi:10.1017/jog.2018.47
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89579
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:12 Sep 2018 21:10
Last Modified:09 Mar 2020 13:19

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