Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core
An important share of paleoclimatic information is buried within the lowermost layers of deep ice cores. Because improving our records further back in time is one of the main challenges in the near future, it is essential to judge how deep these records remain unaltered, since the proximity of the b...
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ftunivbern:oai:boris.unibe.ch:71245 2023-08-20T04:02:31+02:00 Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core Tison, J.-L. de Angelis, M. Littot, G. Wolff, E. Fischer, H. Hansson, M. Bigler, M. Udisti, R. Wegner, A. Jouzel, J. Stenni, B. Johnsen, S. Masson-Delmotte, V. Landais, A. Lipenkov, V. Loulergue, L. Barnola, J.-M. Petit, J.-R. Delmonte, B. Dreyfus, G. Dahl-Jensen, D. Durand, G. Bereiter, B. Schilt, A. Spahni, R. Pol, K. Lorrain, R. Souchez, R. Samyn, D. 2015 application/pdf https://boris.unibe.ch/71245/1/tison15tc.pdf https://boris.unibe.ch/71245/ eng eng Copernicus Publications https://boris.unibe.ch/71245/ info:eu-repo/semantics/openAccess Tison, J.-L.; de Angelis, M.; Littot, G.; Wolff, E.; Fischer, H.; Hansson, M.; Bigler, M.; Udisti, R.; Wegner, A.; Jouzel, J.; Stenni, B.; Johnsen, S.; Masson-Delmotte, V.; Landais, A.; Lipenkov, V.; Loulergue, L.; Barnola, J.-M.; Petit, J.-R.; Delmonte, B.; Dreyfus, G.; . (2015). Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core. The Cryosphere, 9(4), pp. 1633-1648. Copernicus Publications 10.5194/tc-9-1633-2015 <http://dx.doi.org/10.5194/tc-9-1633-2015> 530 Physics info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion PeerReviewed 2015 ftunivbern https://doi.org/10.5194/tc-9-1633-2015 2023-07-31T21:19:27Z An important share of paleoclimatic information is buried within the lowermost layers of deep ice cores. Because improving our records further back in time is one of the main challenges in the near future, it is essential to judge how deep these records remain unaltered, since the proximity of the bedrock is likely to interfere both with the recorded temporal sequence and the ice properties. In this paper, we present a multiparametric study (δD-δ18Oice, δ18Oatm, total air content, CO2, CH4, N2O, dust, high-resolution chemistry, ice texture) of the bottom 60 m of the EPICA (European Project for Ice Coring in Antarctica) Dome C ice core from central Antarctica. These bottom layers were subdivided into two distinct facies: the lower 12 m showing visible solid inclusions (basal dispersed ice facies) and the upper 48 m, which we will refer to as the "basal clean ice facies". Some of the data are consistent with a pristine paleoclimatic signal, others show clear anomalies. It is demonstrated that neither large-scale bottom refreezing of subglacial water, nor mixing (be it internal or with a local basal end term from a previous/initial ice sheet configuration) can explain the observed bottom-ice properties. We focus on the high-resolution chemical profiles and on the available remote sensing data on the subglacial topography of the site to propose a mechanism by which relative stretching of the bottom-ice sheet layers is made possible, due to the progressively confining effect of subglacial valley sides. This stress field change, combined with bottom-ice temperature close to the pressure melting point, induces accelerated migration recrystallization, which results in spatial chemical sorting of the impurities, depending on their state (dissolved vs. solid) and if they are involved or not in salt formation. This chemical sorting effect is responsible for the progressive build-up of the visible solid aggregates that therefore mainly originate "from within", and not from incorporation processes of debris from the ice ... Article in Journal/Newspaper Antarc* Antarctica EPICA ice core Ice Sheet The Cryosphere BORIS (Bern Open Repository and Information System, University of Bern) The Cryosphere 9 4 1633 1648 |
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Open Polar |
collection |
BORIS (Bern Open Repository and Information System, University of Bern) |
op_collection_id |
ftunivbern |
language |
English |
topic |
530 Physics |
spellingShingle |
530 Physics Tison, J.-L. de Angelis, M. Littot, G. Wolff, E. Fischer, H. Hansson, M. Bigler, M. Udisti, R. Wegner, A. Jouzel, J. Stenni, B. Johnsen, S. Masson-Delmotte, V. Landais, A. Lipenkov, V. Loulergue, L. Barnola, J.-M. Petit, J.-R. Delmonte, B. Dreyfus, G. Dahl-Jensen, D. Durand, G. Bereiter, B. Schilt, A. Spahni, R. Pol, K. Lorrain, R. Souchez, R. Samyn, D. Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core |
topic_facet |
530 Physics |
description |
An important share of paleoclimatic information is buried within the lowermost layers of deep ice cores. Because improving our records further back in time is one of the main challenges in the near future, it is essential to judge how deep these records remain unaltered, since the proximity of the bedrock is likely to interfere both with the recorded temporal sequence and the ice properties. In this paper, we present a multiparametric study (δD-δ18Oice, δ18Oatm, total air content, CO2, CH4, N2O, dust, high-resolution chemistry, ice texture) of the bottom 60 m of the EPICA (European Project for Ice Coring in Antarctica) Dome C ice core from central Antarctica. These bottom layers were subdivided into two distinct facies: the lower 12 m showing visible solid inclusions (basal dispersed ice facies) and the upper 48 m, which we will refer to as the "basal clean ice facies". Some of the data are consistent with a pristine paleoclimatic signal, others show clear anomalies. It is demonstrated that neither large-scale bottom refreezing of subglacial water, nor mixing (be it internal or with a local basal end term from a previous/initial ice sheet configuration) can explain the observed bottom-ice properties. We focus on the high-resolution chemical profiles and on the available remote sensing data on the subglacial topography of the site to propose a mechanism by which relative stretching of the bottom-ice sheet layers is made possible, due to the progressively confining effect of subglacial valley sides. This stress field change, combined with bottom-ice temperature close to the pressure melting point, induces accelerated migration recrystallization, which results in spatial chemical sorting of the impurities, depending on their state (dissolved vs. solid) and if they are involved or not in salt formation. This chemical sorting effect is responsible for the progressive build-up of the visible solid aggregates that therefore mainly originate "from within", and not from incorporation processes of debris from the ice ... |
format |
Article in Journal/Newspaper |
author |
Tison, J.-L. de Angelis, M. Littot, G. Wolff, E. Fischer, H. Hansson, M. Bigler, M. Udisti, R. Wegner, A. Jouzel, J. Stenni, B. Johnsen, S. Masson-Delmotte, V. Landais, A. Lipenkov, V. Loulergue, L. Barnola, J.-M. Petit, J.-R. Delmonte, B. Dreyfus, G. Dahl-Jensen, D. Durand, G. Bereiter, B. Schilt, A. Spahni, R. Pol, K. Lorrain, R. Souchez, R. Samyn, D. |
author_facet |
Tison, J.-L. de Angelis, M. Littot, G. Wolff, E. Fischer, H. Hansson, M. Bigler, M. Udisti, R. Wegner, A. Jouzel, J. Stenni, B. Johnsen, S. Masson-Delmotte, V. Landais, A. Lipenkov, V. Loulergue, L. Barnola, J.-M. Petit, J.-R. Delmonte, B. Dreyfus, G. Dahl-Jensen, D. Durand, G. Bereiter, B. Schilt, A. Spahni, R. Pol, K. Lorrain, R. Souchez, R. Samyn, D. |
author_sort |
Tison, J.-L. |
title |
Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core |
title_short |
Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core |
title_full |
Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core |
title_fullStr |
Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core |
title_full_unstemmed |
Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core |
title_sort |
retrieving the paleoclimatic signal from the deeper part of the epica dome c ice core |
publisher |
Copernicus Publications |
publishDate |
2015 |
url |
https://boris.unibe.ch/71245/1/tison15tc.pdf https://boris.unibe.ch/71245/ |
genre |
Antarc* Antarctica EPICA ice core Ice Sheet The Cryosphere |
genre_facet |
Antarc* Antarctica EPICA ice core Ice Sheet The Cryosphere |
op_source |
Tison, J.-L.; de Angelis, M.; Littot, G.; Wolff, E.; Fischer, H.; Hansson, M.; Bigler, M.; Udisti, R.; Wegner, A.; Jouzel, J.; Stenni, B.; Johnsen, S.; Masson-Delmotte, V.; Landais, A.; Lipenkov, V.; Loulergue, L.; Barnola, J.-M.; Petit, J.-R.; Delmonte, B.; Dreyfus, G.; . (2015). Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core. The Cryosphere, 9(4), pp. 1633-1648. Copernicus Publications 10.5194/tc-9-1633-2015 <http://dx.doi.org/10.5194/tc-9-1633-2015> |
op_relation |
https://boris.unibe.ch/71245/ |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/tc-9-1633-2015 |
container_title |
The Cryosphere |
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9 |
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4 |
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1633 |
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1648 |
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