Constant bottom water flow into the Indian Ocean for the past 140 ka indicated by sediment (231)Pa/(230)Th ratios
A down-core 231Pa/230Th record has been measured from the southwestern Indian Ocean to reconstruct the history of deep water flow into this basin over the last glacial-interglacial cycle. The (231Paxs/230Thxs)0 ratio throughout the record is nearly constant at approximately 0.055, significantly lowe...
Published in: | Paleoceanography |
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Format: | Article in Journal/Newspaper |
Language: | English |
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2016
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Online Access: | https://doi.org/10.1029/2007PA001415 https://ora.ox.ac.uk/objects/uuid:fcab2169-ad1c-4bfc-b4f4-353016219509 |
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ftuloxford:oai:ora.ox.ac.uk:uuid:fcab2169-ad1c-4bfc-b4f4-353016219509 2023-05-15T13:59:55+02:00 Constant bottom water flow into the Indian Ocean for the past 140 ka indicated by sediment (231)Pa/(230)Th ratios Thomas, A Henderson, G McCave, I 2016-07-29 https://doi.org/10.1029/2007PA001415 https://ora.ox.ac.uk/objects/uuid:fcab2169-ad1c-4bfc-b4f4-353016219509 eng eng doi:10.1029/2007PA001415 https://ora.ox.ac.uk/objects/uuid:fcab2169-ad1c-4bfc-b4f4-353016219509 https://doi.org/10.1029/2007PA001415 info:eu-repo/semantics/embargoedAccess Journal article 2016 ftuloxford https://doi.org/10.1029/2007PA001415 2022-06-28T20:28:51Z A down-core 231Pa/230Th record has been measured from the southwestern Indian Ocean to reconstruct the history of deep water flow into this basin over the last glacial-interglacial cycle. The (231Paxs/230Thxs)0 ratio throughout the record is nearly constant at approximately 0.055, significantly lower than the production ratio of 0.093, indicating that the proxy is sensitive to changes in circulation and/or sediment flux at this site. The consistent value suggests that there has been no change in the inflow of Antarctic Bottom Water to the Indian Ocean during the last 140 ka, in contrast to the changes in deep circulation thought to occur in other ocean basins. The stability of the (231Paxs/230Thxs)0 value in the record contrasts with an existing sortable silt (SS) record from the same core. The observed SS variability is attributed to a local geostrophic effect amplifying small changes in circulation. A record of authigenic U from the same core suggests that there was reduced oxygen in bottom waters at the core locality during glacial periods. The consistency of the (231Paxs /230Thxs)0 record implies that this could not have arisen by local changes in productivity, thus suggesting a far-field control: either globally reduced bottom water oxygenation or increased productivity south of the Opal Belt during glacials. Copyright 2007 by the American Geophysical Union. Article in Journal/Newspaper Antarc* Antarctic ORA - Oxford University Research Archive Antarctic Indian Paleoceanography 22 4 n/a n/a |
institution |
Open Polar |
collection |
ORA - Oxford University Research Archive |
op_collection_id |
ftuloxford |
language |
English |
description |
A down-core 231Pa/230Th record has been measured from the southwestern Indian Ocean to reconstruct the history of deep water flow into this basin over the last glacial-interglacial cycle. The (231Paxs/230Thxs)0 ratio throughout the record is nearly constant at approximately 0.055, significantly lower than the production ratio of 0.093, indicating that the proxy is sensitive to changes in circulation and/or sediment flux at this site. The consistent value suggests that there has been no change in the inflow of Antarctic Bottom Water to the Indian Ocean during the last 140 ka, in contrast to the changes in deep circulation thought to occur in other ocean basins. The stability of the (231Paxs/230Thxs)0 value in the record contrasts with an existing sortable silt (SS) record from the same core. The observed SS variability is attributed to a local geostrophic effect amplifying small changes in circulation. A record of authigenic U from the same core suggests that there was reduced oxygen in bottom waters at the core locality during glacial periods. The consistency of the (231Paxs /230Thxs)0 record implies that this could not have arisen by local changes in productivity, thus suggesting a far-field control: either globally reduced bottom water oxygenation or increased productivity south of the Opal Belt during glacials. Copyright 2007 by the American Geophysical Union. |
format |
Article in Journal/Newspaper |
author |
Thomas, A Henderson, G McCave, I |
spellingShingle |
Thomas, A Henderson, G McCave, I Constant bottom water flow into the Indian Ocean for the past 140 ka indicated by sediment (231)Pa/(230)Th ratios |
author_facet |
Thomas, A Henderson, G McCave, I |
author_sort |
Thomas, A |
title |
Constant bottom water flow into the Indian Ocean for the past 140 ka indicated by sediment (231)Pa/(230)Th ratios |
title_short |
Constant bottom water flow into the Indian Ocean for the past 140 ka indicated by sediment (231)Pa/(230)Th ratios |
title_full |
Constant bottom water flow into the Indian Ocean for the past 140 ka indicated by sediment (231)Pa/(230)Th ratios |
title_fullStr |
Constant bottom water flow into the Indian Ocean for the past 140 ka indicated by sediment (231)Pa/(230)Th ratios |
title_full_unstemmed |
Constant bottom water flow into the Indian Ocean for the past 140 ka indicated by sediment (231)Pa/(230)Th ratios |
title_sort |
constant bottom water flow into the indian ocean for the past 140 ka indicated by sediment (231)pa/(230)th ratios |
publishDate |
2016 |
url |
https://doi.org/10.1029/2007PA001415 https://ora.ox.ac.uk/objects/uuid:fcab2169-ad1c-4bfc-b4f4-353016219509 |
geographic |
Antarctic Indian |
geographic_facet |
Antarctic Indian |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_relation |
doi:10.1029/2007PA001415 https://ora.ox.ac.uk/objects/uuid:fcab2169-ad1c-4bfc-b4f4-353016219509 https://doi.org/10.1029/2007PA001415 |
op_rights |
info:eu-repo/semantics/embargoedAccess |
op_doi |
https://doi.org/10.1029/2007PA001415 |
container_title |
Paleoceanography |
container_volume |
22 |
container_issue |
4 |
container_start_page |
n/a |
op_container_end_page |
n/a |
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1766268841542811648 |