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

Minchew, Brent M.; Meyer, Colin R.; Robel, Alexander A.; Gudmundsson, G. Hilmar ORCID: https://orcid.org/0000-0003-4236-5369; 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). 583-594. 10.1017/jog.2018.47

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Official URL: http://dx.doi.org/10.1017/jog.2018.47

Abstract/Summary

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:	Publication - Article
Digital Object Identifier (DOI):	10.1017/jog.2018.47
ISSN:	0022-1430
Additional Keywords:	anisotropic ice flow, Antarctic glaciology, glacial rheology, glacier flow, ice rheology
Date made live:	18 Sep 2018 08:17 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/520981

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1017/jog.2018.47

ISSN:

0022-1430

Additional Keywords:

anisotropic ice flow, Antarctic glaciology, glacial rheology, glacier flow, ice rheology

Date made live:

18 Sep 2018 08:17 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/520981