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...
Main Authors: | , , , , , |
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Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
American Geophysical Union
2009
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Subjects: | |
Online Access: | https://doi.org/10.7916/D8S1829D |
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author | Gherardi, J. -M. Labeyrie, L. Nave, S. Francois, R. McManus, Jerry F. Cortijo, E. |
author_facet | Gherardi, J. -M. Labeyrie, L. Nave, S. Francois, R. McManus, Jerry F. Cortijo, E. |
author_sort | Gherardi, J. -M. |
collection | Columbia University: Academic Commons |
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. |
format | Article in Journal/Newspaper |
genre | North Atlantic |
genre_facet | North Atlantic |
id | ftcolumbiauniv:oai:academiccommons.columbia.edu:10.7916/D8S1829D |
institution | Open Polar |
language | English |
op_collection_id | ftcolumbiauniv |
op_doi | https://doi.org/10.7916/D8S1829D |
op_relation | https://doi.org/10.7916/D8S1829D |
publishDate | 2009 |
publisher | American Geophysical Union |
record_format | openpolar |
spelling | ftcolumbiauniv:oai:academiccommons.columbia.edu:10.7916/D8S1829D 2025-01-16T23:33:20+00:00 Glacial-interglacial circulation changes inferred from 231Pa/230Th sedimentary record in the North Atlantic region Gherardi, J. -M. Labeyrie, L. Nave, S. Francois, R. McManus, Jerry F. Cortijo, E. 2009 https://doi.org/10.7916/D8S1829D English eng American Geophysical Union https://doi.org/10.7916/D8S1829D Ocean circulation--Research Paleoceanography Last Glacial Maximum Marine sediments--Analysis Chemical oceanography Hydrology Submarine geology Articles 2009 ftcolumbiauniv https://doi.org/10.7916/D8S1829D 2023-06-18T05:36:30Z 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. Article in Journal/Newspaper North Atlantic Columbia University: Academic Commons |
spellingShingle | Ocean circulation--Research Paleoceanography Last Glacial Maximum Marine sediments--Analysis Chemical oceanography Hydrology Submarine geology Gherardi, J. -M. Labeyrie, L. Nave, S. Francois, R. McManus, Jerry F. Cortijo, E. Glacial-interglacial circulation changes inferred from 231Pa/230Th sedimentary record in the North Atlantic region |
title | 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_short | 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 |
topic | Ocean circulation--Research Paleoceanography Last Glacial Maximum Marine sediments--Analysis Chemical oceanography Hydrology Submarine geology |
topic_facet | Ocean circulation--Research Paleoceanography Last Glacial Maximum Marine sediments--Analysis Chemical oceanography Hydrology Submarine geology |
url | https://doi.org/10.7916/D8S1829D |