Weertman regelation, multiple refreezing events and the isotopic evolution of the basal ice layer
Abstract A simple model is developed to simulate the isotopic fractionation which accompanies Weertman regelation at the bed of temperate-based glaciers. The fractionation equations of Jouzel and Souchez (1982) are applied to multiple refreezing events over measured glacier-bed profiles, and mass ba...
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Cambridge University Press (CUP)
1993
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Online Access: | http://dx.doi.org/10.1017/s002214300001594x https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214300001594X |
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crcambridgeupr:10.1017/s002214300001594x 2024-06-16T07:41:10+00:00 Weertman regelation, multiple refreezing events and the isotopic evolution of the basal ice layer Hubbard, Bryn Sharp, Martin 1993 http://dx.doi.org/10.1017/s002214300001594x https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214300001594X en eng Cambridge University Press (CUP) Journal of Glaciology volume 39, issue 132, page 275-291 ISSN 0022-1430 1727-5652 journal-article 1993 crcambridgeupr https://doi.org/10.1017/s002214300001594x 2024-05-22T12:56:29Z Abstract A simple model is developed to simulate the isotopic fractionation which accompanies Weertman regelation at the bed of temperate-based glaciers. The fractionation equations of Jouzel and Souchez (1982) are applied to multiple refreezing events over measured glacier-bed profiles, and mass balance is maintained as the basal ice and meltwater produced at one bedrock hummock enter the next. Simulation results indicate that undeformed regelation ice layers are on the order of millimetres to centimetres thick, often being completely melted at the stoss face of certain hummocks and exceptionally reaching a thickness in excess of 10 cm. Neither the internal morphology nor the isotopic composition of these layers is constant, but both vary down-glacier in accordance with bedrock configuration. A glacier-wide fractionation process is identified whereby heavy isotopes are preferentially removed from the basal meltwater film and incorporated into the basal ice. This process might go some way to explaining the anomalously “light” isotopic composition measured in base-flow waters leaving some glaciers. Vertical isotope profiles through undeformed basal ice layers are reconstructed and show that significant isotopic excursions can occur at a scale of millimeteres, while the range of isotopic compositions within such multi-layered regelation ice is greater than that which would occur in ice produced by a single refreezing event. In circumstances where the regelation system is disrupted by removal of film waters into a network of linked cavities, it is found that the remaining basal ice may be significantly enriched in heavy isotopes relative to the composition of the initial mass inputs to the system. Heavy isotope enrichment of this magnitude and consideration of the thickness of the basal ice layers concerned may explain the absence of recorded basal ice samples heavy enough to have been formed in equilibrium with subglacial precipitates sampled at one of the sites (Glacier de Tsanfleuron) and reported in an earlier ... Article in Journal/Newspaper Journal of Glaciology Cambridge University Press Weertman ENVELOPE(-67.753,-67.753,-66.972,-66.972) Journal of Glaciology 39 132 275 291 |
institution |
Open Polar |
collection |
Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
description |
Abstract A simple model is developed to simulate the isotopic fractionation which accompanies Weertman regelation at the bed of temperate-based glaciers. The fractionation equations of Jouzel and Souchez (1982) are applied to multiple refreezing events over measured glacier-bed profiles, and mass balance is maintained as the basal ice and meltwater produced at one bedrock hummock enter the next. Simulation results indicate that undeformed regelation ice layers are on the order of millimetres to centimetres thick, often being completely melted at the stoss face of certain hummocks and exceptionally reaching a thickness in excess of 10 cm. Neither the internal morphology nor the isotopic composition of these layers is constant, but both vary down-glacier in accordance with bedrock configuration. A glacier-wide fractionation process is identified whereby heavy isotopes are preferentially removed from the basal meltwater film and incorporated into the basal ice. This process might go some way to explaining the anomalously “light” isotopic composition measured in base-flow waters leaving some glaciers. Vertical isotope profiles through undeformed basal ice layers are reconstructed and show that significant isotopic excursions can occur at a scale of millimeteres, while the range of isotopic compositions within such multi-layered regelation ice is greater than that which would occur in ice produced by a single refreezing event. In circumstances where the regelation system is disrupted by removal of film waters into a network of linked cavities, it is found that the remaining basal ice may be significantly enriched in heavy isotopes relative to the composition of the initial mass inputs to the system. Heavy isotope enrichment of this magnitude and consideration of the thickness of the basal ice layers concerned may explain the absence of recorded basal ice samples heavy enough to have been formed in equilibrium with subglacial precipitates sampled at one of the sites (Glacier de Tsanfleuron) and reported in an earlier ... |
format |
Article in Journal/Newspaper |
author |
Hubbard, Bryn Sharp, Martin |
spellingShingle |
Hubbard, Bryn Sharp, Martin Weertman regelation, multiple refreezing events and the isotopic evolution of the basal ice layer |
author_facet |
Hubbard, Bryn Sharp, Martin |
author_sort |
Hubbard, Bryn |
title |
Weertman regelation, multiple refreezing events and the isotopic evolution of the basal ice layer |
title_short |
Weertman regelation, multiple refreezing events and the isotopic evolution of the basal ice layer |
title_full |
Weertman regelation, multiple refreezing events and the isotopic evolution of the basal ice layer |
title_fullStr |
Weertman regelation, multiple refreezing events and the isotopic evolution of the basal ice layer |
title_full_unstemmed |
Weertman regelation, multiple refreezing events and the isotopic evolution of the basal ice layer |
title_sort |
weertman regelation, multiple refreezing events and the isotopic evolution of the basal ice layer |
publisher |
Cambridge University Press (CUP) |
publishDate |
1993 |
url |
http://dx.doi.org/10.1017/s002214300001594x https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214300001594X |
long_lat |
ENVELOPE(-67.753,-67.753,-66.972,-66.972) |
geographic |
Weertman |
geographic_facet |
Weertman |
genre |
Journal of Glaciology |
genre_facet |
Journal of Glaciology |
op_source |
Journal of Glaciology volume 39, issue 132, page 275-291 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s002214300001594x |
container_title |
Journal of Glaciology |
container_volume |
39 |
container_issue |
132 |
container_start_page |
275 |
op_container_end_page |
291 |
_version_ |
1802008292570955776 |