Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 1: The role of grain size and grain size distribution on deformation of the upper 2207 m
The effect of grain size on strain rate of ice in the upper 2207 m in the North Greenland Eemian Ice Drilling (NEEM) deep ice core was investigated using a rheological model based on the composite flow law of Goldsby and Kohlstedt (1997, 2001). The grain size was described by both a mean grain size...
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2020
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ftdoajarticles:oai:doaj.org/article:3c07f83e970f4e4dbc07464023703afe 2023-05-15T16:28:03+02:00 Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 1: The role of grain size and grain size distribution on deformation of the upper 2207 m E.-J. N. Kuiper I. Weikusat J. H. P. de Bresser D. Jansen G. M. Pennock M. R. Drury 2020-07-01T00:00:00Z https://doi.org/10.5194/tc-14-2429-2020 https://doaj.org/article/3c07f83e970f4e4dbc07464023703afe EN eng Copernicus Publications https://tc.copernicus.org/articles/14/2429/2020/tc-14-2429-2020.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-14-2429-2020 1994-0416 1994-0424 https://doaj.org/article/3c07f83e970f4e4dbc07464023703afe The Cryosphere, Vol 14, Pp 2429-2448 (2020) Environmental sciences GE1-350 Geology QE1-996.5 article 2020 ftdoajarticles https://doi.org/10.5194/tc-14-2429-2020 2022-12-31T12:20:04Z The effect of grain size on strain rate of ice in the upper 2207 m in the North Greenland Eemian Ice Drilling (NEEM) deep ice core was investigated using a rheological model based on the composite flow law of Goldsby and Kohlstedt (1997, 2001). The grain size was described by both a mean grain size and a grain size distribution, which allowed the strain rate to be calculated using two different model end-members: (i) the microscale constant stress model where each grain deforms by the same stress and (ii) the microscale constant strain rate model where each grain deforms by the same strain rate. The model results predict that grain-size-sensitive flow produces almost all of the deformation in the upper 2207 m of the NEEM ice core, while dislocation creep hardly contributes to deformation. The difference in calculated strain rate between the two model end-members is relatively small. The predicted strain rate in the fine-grained Glacial ice (that is, ice deposited during the last Glacial maximum at depths of 1419 to 2207 m) varies strongly within this depth range and, furthermore, is about 4–5 times higher than in the coarser-grained Holocene ice (0–1419 m). Two peaks in strain rate are predicted at about 1980 and 2100 m depth. The prediction that grain-size-sensitive creep is the fastest process is inconsistent with the microstructures in the Holocene age ice, indicating that the rate of dislocation creep is underestimated in the model. The occurrence of recrystallization processes in the polar ice that did not occur in the experiments may account for this discrepancy. The prediction of the composite flow law model is consistent with microstructures in the Glacial ice, suggesting that fine-grained layers in the Glacial ice may act as internal preferential sliding zones in the Greenland ice sheet. Article in Journal/Newspaper Greenland ice core Ice Sheet North Greenland The Cryosphere Directory of Open Access Journals: DOAJ Articles Greenland The Cryosphere 14 7 2429 2448 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 E.-J. N. Kuiper I. Weikusat J. H. P. de Bresser D. Jansen G. M. Pennock M. R. Drury Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 1: The role of grain size and grain size distribution on deformation of the upper 2207 m |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
The effect of grain size on strain rate of ice in the upper 2207 m in the North Greenland Eemian Ice Drilling (NEEM) deep ice core was investigated using a rheological model based on the composite flow law of Goldsby and Kohlstedt (1997, 2001). The grain size was described by both a mean grain size and a grain size distribution, which allowed the strain rate to be calculated using two different model end-members: (i) the microscale constant stress model where each grain deforms by the same stress and (ii) the microscale constant strain rate model where each grain deforms by the same strain rate. The model results predict that grain-size-sensitive flow produces almost all of the deformation in the upper 2207 m of the NEEM ice core, while dislocation creep hardly contributes to deformation. The difference in calculated strain rate between the two model end-members is relatively small. The predicted strain rate in the fine-grained Glacial ice (that is, ice deposited during the last Glacial maximum at depths of 1419 to 2207 m) varies strongly within this depth range and, furthermore, is about 4–5 times higher than in the coarser-grained Holocene ice (0–1419 m). Two peaks in strain rate are predicted at about 1980 and 2100 m depth. The prediction that grain-size-sensitive creep is the fastest process is inconsistent with the microstructures in the Holocene age ice, indicating that the rate of dislocation creep is underestimated in the model. The occurrence of recrystallization processes in the polar ice that did not occur in the experiments may account for this discrepancy. The prediction of the composite flow law model is consistent with microstructures in the Glacial ice, suggesting that fine-grained layers in the Glacial ice may act as internal preferential sliding zones in the Greenland ice sheet. |
format |
Article in Journal/Newspaper |
author |
E.-J. N. Kuiper I. Weikusat J. H. P. de Bresser D. Jansen G. M. Pennock M. R. Drury |
author_facet |
E.-J. N. Kuiper I. Weikusat J. H. P. de Bresser D. Jansen G. M. Pennock M. R. Drury |
author_sort |
E.-J. N. Kuiper |
title |
Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 1: The role of grain size and grain size distribution on deformation of the upper 2207 m |
title_short |
Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 1: The role of grain size and grain size distribution on deformation of the upper 2207 m |
title_full |
Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 1: The role of grain size and grain size distribution on deformation of the upper 2207 m |
title_fullStr |
Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 1: The role of grain size and grain size distribution on deformation of the upper 2207 m |
title_full_unstemmed |
Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 1: The role of grain size and grain size distribution on deformation of the upper 2207 m |
title_sort |
using a composite flow law to model deformation in the neem deep ice core, greenland – part 1: the role of grain size and grain size distribution on deformation of the upper 2207 m |
publisher |
Copernicus Publications |
publishDate |
2020 |
url |
https://doi.org/10.5194/tc-14-2429-2020 https://doaj.org/article/3c07f83e970f4e4dbc07464023703afe |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland ice core Ice Sheet North Greenland The Cryosphere |
genre_facet |
Greenland ice core Ice Sheet North Greenland The Cryosphere |
op_source |
The Cryosphere, Vol 14, Pp 2429-2448 (2020) |
op_relation |
https://tc.copernicus.org/articles/14/2429/2020/tc-14-2429-2020.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-14-2429-2020 1994-0416 1994-0424 https://doaj.org/article/3c07f83e970f4e4dbc07464023703afe |
op_doi |
https://doi.org/10.5194/tc-14-2429-2020 |
container_title |
The Cryosphere |
container_volume |
14 |
container_issue |
7 |
container_start_page |
2429 |
op_container_end_page |
2448 |
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1766017656477974528 |