Deep Circulation Changes In The Central South Atlantic During The Past 145 kyrs Reflected In A Combined 231Pa/230Th, Neodymium Isotope And Benthic δC13 Record
Previous work showed that South Atlantic sediments have lower glacial than Holocene 231Pa/230Th, which was attributed to a switch in the flow direction of Atlantic deep-water. Debate exists, however as to the degree to which two processes – circulation and scavenging – determine sedimentary 231Pa/23...
Published in: | Earth and Planetary Science Letters |
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Edith Cowan University, Research Online, Perth, Western Australia
2015
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ftedithcowan:oai:ro.ecu.edu.au:ecuworkspost2013-1599 2023-05-15T17:31:35+02:00 Deep Circulation Changes In The Central South Atlantic During The Past 145 kyrs Reflected In A Combined 231Pa/230Th, Neodymium Isotope And Benthic δC13 Record Jonkers, Lukas Zahn, Rainer Thomas, Alexander Henderson, Gideon Abouchami, Wafa Francois, Roger Masque, Pere Hall, Ian R. Bickert, Torsten 2015-01-01T08:00:00Z https://ro.ecu.edu.au/ecuworkspost2013/598 https://doi.org/10.1016/j.epsl.2015.03.004 unknown Edith Cowan University, Research Online, Perth, Western Australia https://ro.ecu.edu.au/ecuworkspost2013/598 http://dx.doi.org/10.1016/j.epsl.2015.03.004 subscription content Research outputs 2014 to 2021 231Pa/230Th neodymium isotopes benthic δC13 deep ocean circulation South Atlantic Life Sciences text 2015 ftedithcowan https://doi.org/10.1016/j.epsl.2015.03.004 2022-03-19T23:51:55Z Previous work showed that South Atlantic sediments have lower glacial than Holocene 231Pa/230Th, which was attributed to a switch in the flow direction of Atlantic deep-water. Debate exists, however as to the degree to which two processes – circulation and scavenging – determine sedimentary 231Pa/230Th, making this interpretation contentious. Here we address this issue using 145-kyr records of paleocirculation proxies. Benthic foraminiferal δC13, neodymium isotopes (εNd) and sedimentary 231Pa/230Th were all measured in a single sediment core from the South Atlantic subtropical gyre. This site largely excludes the influence of local productivity changes on 231Pa/230Th records. Measured 231Pa/230Th ranges between ∼0.041 during glacials and ∼0.055 during interglacial periods and is consistently lower than the production ratio, indicating export of 231Pa from the central South Atlantic for the entire duration of the record. The lower glacial 231Pa/230Th is regionally consistent, suggesting that basin-scale oceanographic processes cause the decrease. In turn, less radiogenic εNd and lower benthic δC13 confirm the classical picture of an increase in Southern Component Water (SCW) influence in the Atlantic during glacial periods and point to a circulation control on the observed 231Pa/230Th decrease rather than a local productivity change. We suggest that associated with this change in water mass distribution the dominant sink for 231Pa shifted from the margins of the South Atlantic and/or the Southern Ocean during interglacials, to the North Atlantic during glacial periods. Indeed, elevated 231Pa/230Th in the deep North Atlantic during glacials supports this mechanism of northward transport of 231Pa by SCW. Text North Atlantic Southern Ocean Edith Cowan University (ECU, Australia): Research Online Southern Ocean Earth and Planetary Science Letters 419 14 21 |
institution |
Open Polar |
collection |
Edith Cowan University (ECU, Australia): Research Online |
op_collection_id |
ftedithcowan |
language |
unknown |
topic |
231Pa/230Th neodymium isotopes benthic δC13 deep ocean circulation South Atlantic Life Sciences |
spellingShingle |
231Pa/230Th neodymium isotopes benthic δC13 deep ocean circulation South Atlantic Life Sciences Jonkers, Lukas Zahn, Rainer Thomas, Alexander Henderson, Gideon Abouchami, Wafa Francois, Roger Masque, Pere Hall, Ian R. Bickert, Torsten Deep Circulation Changes In The Central South Atlantic During The Past 145 kyrs Reflected In A Combined 231Pa/230Th, Neodymium Isotope And Benthic δC13 Record |
topic_facet |
231Pa/230Th neodymium isotopes benthic δC13 deep ocean circulation South Atlantic Life Sciences |
description |
Previous work showed that South Atlantic sediments have lower glacial than Holocene 231Pa/230Th, which was attributed to a switch in the flow direction of Atlantic deep-water. Debate exists, however as to the degree to which two processes – circulation and scavenging – determine sedimentary 231Pa/230Th, making this interpretation contentious. Here we address this issue using 145-kyr records of paleocirculation proxies. Benthic foraminiferal δC13, neodymium isotopes (εNd) and sedimentary 231Pa/230Th were all measured in a single sediment core from the South Atlantic subtropical gyre. This site largely excludes the influence of local productivity changes on 231Pa/230Th records. Measured 231Pa/230Th ranges between ∼0.041 during glacials and ∼0.055 during interglacial periods and is consistently lower than the production ratio, indicating export of 231Pa from the central South Atlantic for the entire duration of the record. The lower glacial 231Pa/230Th is regionally consistent, suggesting that basin-scale oceanographic processes cause the decrease. In turn, less radiogenic εNd and lower benthic δC13 confirm the classical picture of an increase in Southern Component Water (SCW) influence in the Atlantic during glacial periods and point to a circulation control on the observed 231Pa/230Th decrease rather than a local productivity change. We suggest that associated with this change in water mass distribution the dominant sink for 231Pa shifted from the margins of the South Atlantic and/or the Southern Ocean during interglacials, to the North Atlantic during glacial periods. Indeed, elevated 231Pa/230Th in the deep North Atlantic during glacials supports this mechanism of northward transport of 231Pa by SCW. |
format |
Text |
author |
Jonkers, Lukas Zahn, Rainer Thomas, Alexander Henderson, Gideon Abouchami, Wafa Francois, Roger Masque, Pere Hall, Ian R. Bickert, Torsten |
author_facet |
Jonkers, Lukas Zahn, Rainer Thomas, Alexander Henderson, Gideon Abouchami, Wafa Francois, Roger Masque, Pere Hall, Ian R. Bickert, Torsten |
author_sort |
Jonkers, Lukas |
title |
Deep Circulation Changes In The Central South Atlantic During The Past 145 kyrs Reflected In A Combined 231Pa/230Th, Neodymium Isotope And Benthic δC13 Record |
title_short |
Deep Circulation Changes In The Central South Atlantic During The Past 145 kyrs Reflected In A Combined 231Pa/230Th, Neodymium Isotope And Benthic δC13 Record |
title_full |
Deep Circulation Changes In The Central South Atlantic During The Past 145 kyrs Reflected In A Combined 231Pa/230Th, Neodymium Isotope And Benthic δC13 Record |
title_fullStr |
Deep Circulation Changes In The Central South Atlantic During The Past 145 kyrs Reflected In A Combined 231Pa/230Th, Neodymium Isotope And Benthic δC13 Record |
title_full_unstemmed |
Deep Circulation Changes In The Central South Atlantic During The Past 145 kyrs Reflected In A Combined 231Pa/230Th, Neodymium Isotope And Benthic δC13 Record |
title_sort |
deep circulation changes in the central south atlantic during the past 145 kyrs reflected in a combined 231pa/230th, neodymium isotope and benthic δc13 record |
publisher |
Edith Cowan University, Research Online, Perth, Western Australia |
publishDate |
2015 |
url |
https://ro.ecu.edu.au/ecuworkspost2013/598 https://doi.org/10.1016/j.epsl.2015.03.004 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
North Atlantic Southern Ocean |
genre_facet |
North Atlantic Southern Ocean |
op_source |
Research outputs 2014 to 2021 |
op_relation |
https://ro.ecu.edu.au/ecuworkspost2013/598 http://dx.doi.org/10.1016/j.epsl.2015.03.004 |
op_rights |
subscription content |
op_doi |
https://doi.org/10.1016/j.epsl.2015.03.004 |
container_title |
Earth and Planetary Science Letters |
container_volume |
419 |
container_start_page |
14 |
op_container_end_page |
21 |
_version_ |
1766129242656997376 |