Abstract
Ice crystallographic measurements have been made on eight cores retrieved from temperate Glacier de Tsanfleuron, Switzerland. Cores are aligned approximately along a Bow-parallel transect, allowing a stratigraphic model of crystallographic evolution at the glacier to be constructed.
Results indicate the presence of four crystallographic units at the glacier. Unit 1 composed of homogeneous, fine-grained ice with a uniform fabric. is located within c. 20 m of the ice surface in the accumulation area of the glacier. Crystal growth within this unit occurs in the absence of significant stresses, and its rate is closely described by an Arrhenius-type relationship. Unit 2 ice, characterized by the local development of coarser crystals, forms after some decades of Arrhenius growth, marking the initial influence of processes of dynamic recrystallisation. Unit 3 ice, characterized by an abrupt increase in minimum crystal size, occurs at a depth of c. 33 m throughout the glacier. In the accumulation area. this increase coincides with the first evidence of systematic fabric enhancement, interpreted in terms of dynamic recrystallisation. Unit 4 ice, characterized by large, interlocking grains with a multi-modal girdle fabric, develops within c. 10 m of the glacier bed. Here, the measured minimum crystal size is consistent with a steady-state balance between Arrhenius processes of grain growth and strain-related processes of grain-size reduction. These changes are interpreted in terms of the effects of intense, continuous deformation in this basal zone.
Original language | English |
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Title of host publication | Deformation of Glacial Materials |
Editors | Alex Maltman, B. Hubbard, M. J. Hambrey |
Publisher | GEOLOGICAL SOC PUBLISHING HOUSE |
Pages | 23-38 |
Number of pages | 16 |
ISBN (Print) | 978-1862390720, 186239072X |
DOIs | |
Publication status | Published - 14 Nov 2000 |
Event | Conference on Deformation of Glacial Materials - LONDON Duration: 01 Sept 1999 → … |
Publication series
Name | Geological Society Special Publication |
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Publisher | GEOLOGICAL SOC PUBLISHING HOUSE |
Volume | 176 |
ISSN (Print) | 0305-8719 |
Conference
Conference | Conference on Deformation of Glacial Materials |
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City | LONDON |
Period | 01 Sept 1999 → … |
Keywords
- CRYSTAL SIZE
- BORE-HOLE
- FABRICS
- CORE