Glacial-interglacial circulation changes inferred from 231Pa/ 230Th sedimentary record in the North Atlantic region
Studies from the subtropical western and eastern Atlantic Ocean, using the 231Pa/230Th ratio as a kinematic proxy for deep water circulation, provided compelling evidence for a strong link between climate and the rate of meridional overturning circulation (MOC) over the last deglaciation. In this st...
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Online Access: | http://hdl.handle.net/2429/40057 https://doi.org/10.1029/2008PA001696 |
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ftunivbritcolcir:oai:circle.library.ubc.ca:2429/40057 2023-05-15T17:28:53+02:00 Glacial-interglacial circulation changes inferred from 231Pa/ 230Th sedimentary record in the North Atlantic region Francois, Roger University of British Columbia. Pacific Centre for Isotopic and Geochemical Research 2009 http://hdl.handle.net/2429/40057 https://doi.org/10.1029/2008PA001696 eng eng American Geophysical Union 45546 Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ Francois, Roger CC-BY-NC-ND Low-temperature Geochemistry Text Article 2009 ftunivbritcolcir https://doi.org/10.1029/2008PA001696 2019-10-15T18:07:43Z Studies from the subtropical western and eastern Atlantic Ocean, using the 231Pa/230Th ratio as a kinematic proxy for deep water circulation, provided compelling evidence for a strong link between climate and the rate of meridional overturning circulation (MOC) over the last deglaciation. In this study, we present a compilation of existing and new sedimentary 231Pa/230Th records from North Atlantic cores between 1710 and 4550 m water depth. Comparing sedimentary 231Pa/230Th from different depths provides new insights into the evolution of the geometry and rate of deep water formation in the North Atlantic during the last 20,000 years. The 231Pa/230Th ratio measured in upper Holocene sediments indicates slow water renewal above ~2500 m and rapid flushing below, consistent with our understanding of modern circulation. In contrast, during the Last Glacial Maximum (LGM), Glacial North Atlantic Intermediate Water (GNAIW) drove a rapid overturning circulation to a depth of at least ~3000 m depth. Below ~4000 m, water renewal was much slower than today. At the onset of Heinrich event 1, transport by the overturning circulation declined at all depths. GNAIW shoaled above 3000 m and significantly weakened but did not totally shut down. During the Bølling-Allerød (BA) that followed, water renewal rates further decreased above 2000 m but increased below. Our results suggest for the first time that ocean circulation during that period was quite distinct from the modern circulation mode, with a comparatively higher renewal rate above 3000 m and a lower renewal rate below in a pattern similar to the LGM but less accentuated. MOC during the Younger Dryas appears very similar to BA down to 2000 m and slightly slower below. An edited version of this paper was published by AGU. Copyright 2009 American Geophysical Union. Science, Faculty of Earth and Ocean Sciences, Department of Reviewed Faculty Article in Journal/Newspaper North Atlantic University of British Columbia: cIRcle - UBC's Information Repository Paleoceanography 24 2 n/a n/a |
institution |
Open Polar |
collection |
University of British Columbia: cIRcle - UBC's Information Repository |
op_collection_id |
ftunivbritcolcir |
language |
English |
topic |
Low-temperature Geochemistry |
spellingShingle |
Low-temperature Geochemistry Francois, Roger Glacial-interglacial circulation changes inferred from 231Pa/ 230Th sedimentary record in the North Atlantic region |
topic_facet |
Low-temperature Geochemistry |
description |
Studies from the subtropical western and eastern Atlantic Ocean, using the 231Pa/230Th ratio as a kinematic proxy for deep water circulation, provided compelling evidence for a strong link between climate and the rate of meridional overturning circulation (MOC) over the last deglaciation. In this study, we present a compilation of existing and new sedimentary 231Pa/230Th records from North Atlantic cores between 1710 and 4550 m water depth. Comparing sedimentary 231Pa/230Th from different depths provides new insights into the evolution of the geometry and rate of deep water formation in the North Atlantic during the last 20,000 years. The 231Pa/230Th ratio measured in upper Holocene sediments indicates slow water renewal above ~2500 m and rapid flushing below, consistent with our understanding of modern circulation. In contrast, during the Last Glacial Maximum (LGM), Glacial North Atlantic Intermediate Water (GNAIW) drove a rapid overturning circulation to a depth of at least ~3000 m depth. Below ~4000 m, water renewal was much slower than today. At the onset of Heinrich event 1, transport by the overturning circulation declined at all depths. GNAIW shoaled above 3000 m and significantly weakened but did not totally shut down. During the Bølling-Allerød (BA) that followed, water renewal rates further decreased above 2000 m but increased below. Our results suggest for the first time that ocean circulation during that period was quite distinct from the modern circulation mode, with a comparatively higher renewal rate above 3000 m and a lower renewal rate below in a pattern similar to the LGM but less accentuated. MOC during the Younger Dryas appears very similar to BA down to 2000 m and slightly slower below. An edited version of this paper was published by AGU. Copyright 2009 American Geophysical Union. Science, Faculty of Earth and Ocean Sciences, Department of Reviewed Faculty |
author2 |
University of British Columbia. Pacific Centre for Isotopic and Geochemical Research |
format |
Article in Journal/Newspaper |
author |
Francois, Roger |
author_facet |
Francois, Roger |
author_sort |
Francois, Roger |
title |
Glacial-interglacial circulation changes inferred from 231Pa/ 230Th sedimentary record in the North Atlantic region |
title_short |
Glacial-interglacial circulation changes inferred from 231Pa/ 230Th sedimentary record in the North Atlantic region |
title_full |
Glacial-interglacial circulation changes inferred from 231Pa/ 230Th sedimentary record in the North Atlantic region |
title_fullStr |
Glacial-interglacial circulation changes inferred from 231Pa/ 230Th sedimentary record in the North Atlantic region |
title_full_unstemmed |
Glacial-interglacial circulation changes inferred from 231Pa/ 230Th sedimentary record in the North Atlantic region |
title_sort |
glacial-interglacial circulation changes inferred from 231pa/ 230th sedimentary record in the north atlantic region |
publisher |
American Geophysical Union |
publishDate |
2009 |
url |
http://hdl.handle.net/2429/40057 https://doi.org/10.1029/2008PA001696 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
45546 |
op_rights |
Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ Francois, Roger |
op_rightsnorm |
CC-BY-NC-ND |
op_doi |
https://doi.org/10.1029/2008PA001696 |
container_title |
Paleoceanography |
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24 |
container_issue |
2 |
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n/a |
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n/a |
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1766122011850964992 |