New Zealand Journal of Geology and Geophysics abstracts
Strain-rate effects on the strength of debris-laden glacier ice
Wendy Lawson
Christine Elliott
Department of Geography
University of Canterbury
Private Bag 4800
Christchurch, New Zealand
email: wendy.lawson@canterbury.ac.nz
Abstract Knowledge of the rate at which ice deforms
is a key issue for understanding ice mass dynamics. Although the mechanical
behaviour of clean glacier ice is now relatively well understood, there are
many aspects of the behaviour of ice with different physical and chemical
characteristics that remain to be investigated. In this paper, we examine
the effects of strain-rate variations on the measured strength of debris-laden
ice samples recovered from the basal zone of Taylor Glacier, Antarctica, and
compare them with the effects on clean ice from the same glacier. At temperatures
relatively close to the melting point, debris-laden ice strength is strongly
related to strain-rate, whereas clean ice strength is not. At colder temperatures,
the strength of debris-laden ice does not appear to be affected by strain
rate. These results indicate that at higher strain rates, debris-laden ice
is weaker, implying a rate-related strain softening. They also confirm earlier
findings that the behaviour of the basal ice is strongly temperature dependent.
Keywords glaciology; ice rheology; debris-laden ice;
strain-rate; Antarctica
G01032; Received 17 October 2001; accepted 9 December 2002; online publication
date 10 September 2003
New Zealand Journal of Geology & Geophysics, 2003, Vol. 46: 323-330
0028-8306/03/4603-0323 $7.00/0 © The Royal Society of New Zealand
2003
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