Physical analysis of an Antarctic ice core—towards an integration of micro- and macrodynamics of polar ice*
Microstructures from deep ice cores reflect the dynamic conditions of the drill location as well as the thermodynamic history of the drill site and catchment area in great detail. Ice core parameters (crystal lattice-preferred orientation (LPO), grain size, grain shape), mesostructures (visual strat...
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Online Access: | http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5179957/ http://www.ncbi.nlm.nih.gov/pubmed/28025296 https://doi.org/10.1098/rsta.2015.0347 |
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ftpubmed:oai:pubmedcentral.nih.gov:5179957 2023-05-15T13:59:22+02:00 Physical analysis of an Antarctic ice core—towards an integration of micro- and macrodynamics of polar ice* Weikusat, Ilka Jansen, Daniela Binder, Tobias Eichler, Jan Faria, Sérgio H. Wilhelms, Frank Kipfstuhl, Sepp Sheldon, Simon Miller, Heinrich Dahl-Jensen, Dorthe Kleiner, Thomas 2017-02-13 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5179957/ http://www.ncbi.nlm.nih.gov/pubmed/28025296 https://doi.org/10.1098/rsta.2015.0347 en eng The Royal Society Publishing http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5179957/ http://www.ncbi.nlm.nih.gov/pubmed/28025296 http://dx.doi.org/10.1098/rsta.2015.0347 © 2016 The Authors. http://creativecommons.org/licenses/by/4.0/ Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. CC-BY Articles Text 2017 ftpubmed https://doi.org/10.1098/rsta.2015.0347 2017-02-19T01:02:05Z Microstructures from deep ice cores reflect the dynamic conditions of the drill location as well as the thermodynamic history of the drill site and catchment area in great detail. Ice core parameters (crystal lattice-preferred orientation (LPO), grain size, grain shape), mesostructures (visual stratigraphy) as well as borehole deformation were measured in a deep ice core drilled at Kohnen Station, Dronning Maud Land (DML), Antarctica. These observations are used to characterize the local dynamic setting and its rheological as well as microstructural effects at the EDML ice core drilling site (European Project for Ice Coring in Antarctica in DML). The results suggest a division of the core into five distinct sections, interpreted as the effects of changing deformation boundary conditions from triaxial deformation with horizontal extension to bedrock-parallel shear. Region 1 (uppermost approx. 450 m depth) with still small macroscopic strain is dominated by compression of bubbles and strong strain and recrystallization localization. Region 2 (approx. 450–1700 m depth) shows a girdle-type LPO with the girdle plane being perpendicular to grain elongations, which indicates triaxial deformation with dominating horizontal extension. In this region (approx. 1000 m depth), the first subtle traces of shear deformation are observed in the shape-preferred orientation (SPO) by inclination of the grain elongation. Region 3 (approx. 1700–2030 m depth) represents a transitional regime between triaxial deformation and dominance of shear, which becomes apparent in the progression of the girdle to a single maximum LPO and increasing obliqueness of grain elongations. The fully developed single maximum LPO in region 4 (approx. 2030–2385 m depth) is an indicator of shear dominance. Region 5 (below approx. 2385 m depth) is marked by signs of strong shear, such as strong SPO values of grain elongation and strong kink folding of visual layers. The details of structural observations are compared with results from a numerical ice sheet ... Text Antarc* Antarctic Antarctica DML Dronning Maud Land ice core Ice Sheet PubMed Central (PMC) Antarctic Dronning Maud Land Kohnen ENVELOPE(0.000,0.000,-75.000,-75.000) Kohnen Station ENVELOPE(0.000,0.000,-75.000,-75.000) Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 375 2086 20150347 |
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Articles |
spellingShingle |
Articles Weikusat, Ilka Jansen, Daniela Binder, Tobias Eichler, Jan Faria, Sérgio H. Wilhelms, Frank Kipfstuhl, Sepp Sheldon, Simon Miller, Heinrich Dahl-Jensen, Dorthe Kleiner, Thomas Physical analysis of an Antarctic ice core—towards an integration of micro- and macrodynamics of polar ice* |
topic_facet |
Articles |
description |
Microstructures from deep ice cores reflect the dynamic conditions of the drill location as well as the thermodynamic history of the drill site and catchment area in great detail. Ice core parameters (crystal lattice-preferred orientation (LPO), grain size, grain shape), mesostructures (visual stratigraphy) as well as borehole deformation were measured in a deep ice core drilled at Kohnen Station, Dronning Maud Land (DML), Antarctica. These observations are used to characterize the local dynamic setting and its rheological as well as microstructural effects at the EDML ice core drilling site (European Project for Ice Coring in Antarctica in DML). The results suggest a division of the core into five distinct sections, interpreted as the effects of changing deformation boundary conditions from triaxial deformation with horizontal extension to bedrock-parallel shear. Region 1 (uppermost approx. 450 m depth) with still small macroscopic strain is dominated by compression of bubbles and strong strain and recrystallization localization. Region 2 (approx. 450–1700 m depth) shows a girdle-type LPO with the girdle plane being perpendicular to grain elongations, which indicates triaxial deformation with dominating horizontal extension. In this region (approx. 1000 m depth), the first subtle traces of shear deformation are observed in the shape-preferred orientation (SPO) by inclination of the grain elongation. Region 3 (approx. 1700–2030 m depth) represents a transitional regime between triaxial deformation and dominance of shear, which becomes apparent in the progression of the girdle to a single maximum LPO and increasing obliqueness of grain elongations. The fully developed single maximum LPO in region 4 (approx. 2030–2385 m depth) is an indicator of shear dominance. Region 5 (below approx. 2385 m depth) is marked by signs of strong shear, such as strong SPO values of grain elongation and strong kink folding of visual layers. The details of structural observations are compared with results from a numerical ice sheet ... |
format |
Text |
author |
Weikusat, Ilka Jansen, Daniela Binder, Tobias Eichler, Jan Faria, Sérgio H. Wilhelms, Frank Kipfstuhl, Sepp Sheldon, Simon Miller, Heinrich Dahl-Jensen, Dorthe Kleiner, Thomas |
author_facet |
Weikusat, Ilka Jansen, Daniela Binder, Tobias Eichler, Jan Faria, Sérgio H. Wilhelms, Frank Kipfstuhl, Sepp Sheldon, Simon Miller, Heinrich Dahl-Jensen, Dorthe Kleiner, Thomas |
author_sort |
Weikusat, Ilka |
title |
Physical analysis of an Antarctic ice core—towards an integration of micro- and macrodynamics of polar ice* |
title_short |
Physical analysis of an Antarctic ice core—towards an integration of micro- and macrodynamics of polar ice* |
title_full |
Physical analysis of an Antarctic ice core—towards an integration of micro- and macrodynamics of polar ice* |
title_fullStr |
Physical analysis of an Antarctic ice core—towards an integration of micro- and macrodynamics of polar ice* |
title_full_unstemmed |
Physical analysis of an Antarctic ice core—towards an integration of micro- and macrodynamics of polar ice* |
title_sort |
physical analysis of an antarctic ice core—towards an integration of micro- and macrodynamics of polar ice* |
publisher |
The Royal Society Publishing |
publishDate |
2017 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5179957/ http://www.ncbi.nlm.nih.gov/pubmed/28025296 https://doi.org/10.1098/rsta.2015.0347 |
long_lat |
ENVELOPE(0.000,0.000,-75.000,-75.000) ENVELOPE(0.000,0.000,-75.000,-75.000) |
geographic |
Antarctic Dronning Maud Land Kohnen Kohnen Station |
geographic_facet |
Antarctic Dronning Maud Land Kohnen Kohnen Station |
genre |
Antarc* Antarctic Antarctica DML Dronning Maud Land ice core Ice Sheet |
genre_facet |
Antarc* Antarctic Antarctica DML Dronning Maud Land ice core Ice Sheet |
op_relation |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5179957/ http://www.ncbi.nlm.nih.gov/pubmed/28025296 http://dx.doi.org/10.1098/rsta.2015.0347 |
op_rights |
© 2016 The Authors. http://creativecommons.org/licenses/by/4.0/ Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1098/rsta.2015.0347 |
container_title |
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences |
container_volume |
375 |
container_issue |
2086 |
container_start_page |
20150347 |
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1766267911081558016 |