Abrupt changes in deep Atlantic circulation during the transition to full glacial conditions
Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 28 (2013): 253–262, doi:10.1002/palo.20025. Six Ocean Drilling Program (ODP)...
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ftwhoas:oai:darchive.mblwhoilibrary.org:1912/6168 2023-05-15T17:32:04+02:00 Abrupt changes in deep Atlantic circulation during the transition to full glacial conditions Thornalley, David J. R. Barker, Stephen Becker, Julia Hall, Ian R. Knorr, Gregor 2013-05-30 application/pdf text/richtext application/msword https://hdl.handle.net/1912/6168 en_US eng John Wiley & Sons https://doi.org/10.1002/palo.20025 Paleoceanography 28 (2013): 253–262 https://hdl.handle.net/1912/6168 doi:10.1002/palo.20025 Paleoceanography 28 (2013): 253–262 doi:10.1002/palo.20025 Western Boundary Undercurrent Abrupt climate change North Atlantic Glacial Ocean circulation Article 2013 ftwhoas https://doi.org/10.1002/palo.20025 2022-05-28T22:58:56Z Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 28 (2013): 253–262, doi:10.1002/palo.20025. Six Ocean Drilling Program (ODP) sites, in the Northwest Atlantic have been used to investigate kinematic and chemical changes in the “Western Boundary Undercurrent” (WBUC) during the development of full glacial conditions across the Marine Isotope Stage 5a/4 boundary (~70,000 years ago). Sortable silt mean grain size inline image measurements are employed to examine changes in near bottom flow speeds, together with carbon isotopes measured in benthic foraminifera and % planktic foraminiferal fragmentation as proxies for changes in water-mass chemistry. A depth transect of cores, spanning 1.8–4.6 km depth, allows changes in both the strength and depth of the WBUC to be constrained across millennial scale events. inline image measurements reveal that the flow speed structure of the WBUC during warm intervals (“interstadials”) was comparable to modern (Holocene) conditions. However, significant differences are observed during cold intervals, with higher relative flow speeds inferred for the shallow component of the WBUC (~2 km depth) during all cold “stadial” intervals (including Heinrich Stadial 6), and a substantial weakening of the deep component (~3–4 km) during full glacial conditions. Our results therefore reveal that the onset of full glacial conditions was associated with a regime shift to a shallower mode of circulation (involving Glacial North Atlantic Intermediate Water) that was quantitatively distinct from preceding cold stadial events. Furthermore, our chemical proxy data show that the physical response of the WBUC during the last glacial inception was probably coupled to basin-wide changes in the water-mass composition of the deep Northwest Atlantic. This work was supported by the Natural Environment Research Council (NERC, UK) ... Article in Journal/Newspaper North Atlantic Northwest Atlantic Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) Paleoceanography 28 2 253 262 |
institution |
Open Polar |
collection |
Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) |
op_collection_id |
ftwhoas |
language |
English |
topic |
Western Boundary Undercurrent Abrupt climate change North Atlantic Glacial Ocean circulation |
spellingShingle |
Western Boundary Undercurrent Abrupt climate change North Atlantic Glacial Ocean circulation Thornalley, David J. R. Barker, Stephen Becker, Julia Hall, Ian R. Knorr, Gregor Abrupt changes in deep Atlantic circulation during the transition to full glacial conditions |
topic_facet |
Western Boundary Undercurrent Abrupt climate change North Atlantic Glacial Ocean circulation |
description |
Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 28 (2013): 253–262, doi:10.1002/palo.20025. Six Ocean Drilling Program (ODP) sites, in the Northwest Atlantic have been used to investigate kinematic and chemical changes in the “Western Boundary Undercurrent” (WBUC) during the development of full glacial conditions across the Marine Isotope Stage 5a/4 boundary (~70,000 years ago). Sortable silt mean grain size inline image measurements are employed to examine changes in near bottom flow speeds, together with carbon isotopes measured in benthic foraminifera and % planktic foraminiferal fragmentation as proxies for changes in water-mass chemistry. A depth transect of cores, spanning 1.8–4.6 km depth, allows changes in both the strength and depth of the WBUC to be constrained across millennial scale events. inline image measurements reveal that the flow speed structure of the WBUC during warm intervals (“interstadials”) was comparable to modern (Holocene) conditions. However, significant differences are observed during cold intervals, with higher relative flow speeds inferred for the shallow component of the WBUC (~2 km depth) during all cold “stadial” intervals (including Heinrich Stadial 6), and a substantial weakening of the deep component (~3–4 km) during full glacial conditions. Our results therefore reveal that the onset of full glacial conditions was associated with a regime shift to a shallower mode of circulation (involving Glacial North Atlantic Intermediate Water) that was quantitatively distinct from preceding cold stadial events. Furthermore, our chemical proxy data show that the physical response of the WBUC during the last glacial inception was probably coupled to basin-wide changes in the water-mass composition of the deep Northwest Atlantic. This work was supported by the Natural Environment Research Council (NERC, UK) ... |
format |
Article in Journal/Newspaper |
author |
Thornalley, David J. R. Barker, Stephen Becker, Julia Hall, Ian R. Knorr, Gregor |
author_facet |
Thornalley, David J. R. Barker, Stephen Becker, Julia Hall, Ian R. Knorr, Gregor |
author_sort |
Thornalley, David J. R. |
title |
Abrupt changes in deep Atlantic circulation during the transition to full glacial conditions |
title_short |
Abrupt changes in deep Atlantic circulation during the transition to full glacial conditions |
title_full |
Abrupt changes in deep Atlantic circulation during the transition to full glacial conditions |
title_fullStr |
Abrupt changes in deep Atlantic circulation during the transition to full glacial conditions |
title_full_unstemmed |
Abrupt changes in deep Atlantic circulation during the transition to full glacial conditions |
title_sort |
abrupt changes in deep atlantic circulation during the transition to full glacial conditions |
publisher |
John Wiley & Sons |
publishDate |
2013 |
url |
https://hdl.handle.net/1912/6168 |
genre |
North Atlantic Northwest Atlantic |
genre_facet |
North Atlantic Northwest Atlantic |
op_source |
Paleoceanography 28 (2013): 253–262 doi:10.1002/palo.20025 |
op_relation |
https://doi.org/10.1002/palo.20025 Paleoceanography 28 (2013): 253–262 https://hdl.handle.net/1912/6168 doi:10.1002/palo.20025 |
op_doi |
https://doi.org/10.1002/palo.20025 |
container_title |
Paleoceanography |
container_volume |
28 |
container_issue |
2 |
container_start_page |
253 |
op_container_end_page |
262 |
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1766130001453776896 |