Physical modelling of the rheology of clean and sediment-rich polycrystalline ice using a geotechnical centrifuge: potential applications
Published:January 01, 2000
Duncan H. B. Irving, Brice R. Rea, Charles Harris, 2000. "Physical modelling of the rheology of clean and sediment-rich polycrystalline ice using a geotechnical centrifuge: potential applications", Deformation of Glacial Materials, Alex J. Maltman, Bryn Hubbard, Michael J. Hambrey
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A self-weight stress gradient is developed through the body of a glacier such that strain rates are highest in the lowest few metres as described by Glen's flow law and other stress- and temperature-dependent relationships. Conventional laboratory technology limits the size and complexity of physical models of glacier ice, particularly in the complicated basal ice layers. A geotechnical centrifuge can be used to replicate such stress regimes in a controlled environment using a scaled model of the field ‘prototype’ that is subjected to an accelerational field that is a factor N greater than that of the Earth, g. The development of a technique employing a geotechnical centrifuge as a testbed for such physical models is described. Strain rates of 10-6 –10–7 s-1 are calculated for models of low and moderate stress, high temperature ice. Relationships between the physical models and glacial systems suggest a scaling of the effects of transient creep by 1 : N, diffusion creep by 1 : N2–1 : N3 and power law creep by 1:1. Preliminary results demonstrate the potential applications of the technique in the fields of glaciology and glacial geomorphology, in particular where low stresses and high temperatures are key characteristics of a glacial system and in systems containing several stratigraphic units.
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Deformation of Glacial Materials
The flow of glacier ice can produce structures that are striking and beautiful. Associated sediments, too, can develop spectacular deformation structures, and examples are remarkbly well preserved in Quaternary deposits. Although such features have long been recognized, they are now the subject of new attention from glaciologists and glacial geologists.
This collection of papers addresses how the methods for unravelling deformation structures evolved in recent years by structural geologists can be used for glacial materials, and the opportunities offered to structural geologists by glacial materials for studying deformation in rocks.