Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 2: The role of grain size and premelting on ice deformation at high homologous temperature
The ice microstructure in the lower part of the North Greenland Eemian Ice Drilling (NEEM) ice core consists of relatively fine-grained ice with a single maximum crystallographic preferred orientation (CPO) alternated by much coarser-grained ice with a partial (great circle) girdle or multi-maxima C...
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ftdoajarticles:oai:doaj.org/article:e7a672880cf947fa976261315e5b5cc6 2023-05-15T16:28:28+02:00 Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 2: The role of grain size and premelting on ice deformation at high homologous temperature E.-J. N. Kuiper J. H. P. de Bresser M. R. Drury J. Eichler G. M. Pennock I. Weikusat 2020-07-01T00:00:00Z https://doi.org/10.5194/tc-14-2449-2020 https://doaj.org/article/e7a672880cf947fa976261315e5b5cc6 EN eng Copernicus Publications https://tc.copernicus.org/articles/14/2449/2020/tc-14-2449-2020.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-14-2449-2020 1994-0416 1994-0424 https://doaj.org/article/e7a672880cf947fa976261315e5b5cc6 The Cryosphere, Vol 14, Pp 2449-2467 (2020) Environmental sciences GE1-350 Geology QE1-996.5 article 2020 ftdoajarticles https://doi.org/10.5194/tc-14-2449-2020 2022-12-31T03:31:05Z The ice microstructure in the lower part of the North Greenland Eemian Ice Drilling (NEEM) ice core consists of relatively fine-grained ice with a single maximum crystallographic preferred orientation (CPO) alternated by much coarser-grained ice with a partial (great circle) girdle or multi-maxima CPO. In this study, the grain-size-sensitive (GSS) composite flow law of Goldsby and Kohlstedt (2001) was used to study the effects of grain size and premelting (liquid-like layer along the grain boundaries) on strain rate in the lower part of the NEEM ice core. The results show that the strain rates predicted in the fine-grained layers are about an order of magnitude higher than in the much coarser-grained layers. The dominant deformation mechanisms, based on the flow relation of Goldsby and Kohlstedt (2001), between the layers is also different, with basal slip rate limited by grain boundary sliding (GBS-limited creep) being the dominant deformation mechanism in the finer-grained layers, while GBS-limited creep and dislocation creep (basal slip rate limited by non-basal slip) contribute both roughly equally to bulk strain in the coarse-grained layers. Due to the large difference in microstructure between finer-grained ice and the coarse-grained ice at premelting temperatures ( T >262 K), it is expected that the fine-grained layers deform at high strain rates, while the coarse-grained layers are relatively stagnant. The difference in microstructure, and consequently in viscosity, between impurity-rich and low-impurity ice can have important consequences for ice dynamics close to the bedrock. Article in Journal/Newspaper Greenland ice core North Greenland The Cryosphere Directory of Open Access Journals: DOAJ Articles Greenland The Cryosphere 14 7 2449 2467 |
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 J. H. P. de Bresser M. R. Drury J. Eichler G. M. Pennock I. Weikusat Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 2: The role of grain size and premelting on ice deformation at high homologous temperature |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
The ice microstructure in the lower part of the North Greenland Eemian Ice Drilling (NEEM) ice core consists of relatively fine-grained ice with a single maximum crystallographic preferred orientation (CPO) alternated by much coarser-grained ice with a partial (great circle) girdle or multi-maxima CPO. In this study, the grain-size-sensitive (GSS) composite flow law of Goldsby and Kohlstedt (2001) was used to study the effects of grain size and premelting (liquid-like layer along the grain boundaries) on strain rate in the lower part of the NEEM ice core. The results show that the strain rates predicted in the fine-grained layers are about an order of magnitude higher than in the much coarser-grained layers. The dominant deformation mechanisms, based on the flow relation of Goldsby and Kohlstedt (2001), between the layers is also different, with basal slip rate limited by grain boundary sliding (GBS-limited creep) being the dominant deformation mechanism in the finer-grained layers, while GBS-limited creep and dislocation creep (basal slip rate limited by non-basal slip) contribute both roughly equally to bulk strain in the coarse-grained layers. Due to the large difference in microstructure between finer-grained ice and the coarse-grained ice at premelting temperatures ( T >262 K), it is expected that the fine-grained layers deform at high strain rates, while the coarse-grained layers are relatively stagnant. The difference in microstructure, and consequently in viscosity, between impurity-rich and low-impurity ice can have important consequences for ice dynamics close to the bedrock. |
format |
Article in Journal/Newspaper |
author |
E.-J. N. Kuiper J. H. P. de Bresser M. R. Drury J. Eichler G. M. Pennock I. Weikusat |
author_facet |
E.-J. N. Kuiper J. H. P. de Bresser M. R. Drury J. Eichler G. M. Pennock I. Weikusat |
author_sort |
E.-J. N. Kuiper |
title |
Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 2: The role of grain size and premelting on ice deformation at high homologous temperature |
title_short |
Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 2: The role of grain size and premelting on ice deformation at high homologous temperature |
title_full |
Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 2: The role of grain size and premelting on ice deformation at high homologous temperature |
title_fullStr |
Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 2: The role of grain size and premelting on ice deformation at high homologous temperature |
title_full_unstemmed |
Using a composite flow law to model deformation in the NEEM deep ice core, Greenland – Part 2: The role of grain size and premelting on ice deformation at high homologous temperature |
title_sort |
using a composite flow law to model deformation in the neem deep ice core, greenland – part 2: the role of grain size and premelting on ice deformation at high homologous temperature |
publisher |
Copernicus Publications |
publishDate |
2020 |
url |
https://doi.org/10.5194/tc-14-2449-2020 https://doaj.org/article/e7a672880cf947fa976261315e5b5cc6 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland ice core North Greenland The Cryosphere |
genre_facet |
Greenland ice core North Greenland The Cryosphere |
op_source |
The Cryosphere, Vol 14, Pp 2449-2467 (2020) |
op_relation |
https://tc.copernicus.org/articles/14/2449/2020/tc-14-2449-2020.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-14-2449-2020 1994-0416 1994-0424 https://doaj.org/article/e7a672880cf947fa976261315e5b5cc6 |
op_doi |
https://doi.org/10.5194/tc-14-2449-2020 |
container_title |
The Cryosphere |
container_volume |
14 |
container_issue |
7 |
container_start_page |
2449 |
op_container_end_page |
2467 |
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1766018129103683584 |