Pleistocene vertical carbon isotope and carbonate gradients in the South Atlantic sector of the Southern Ocean
We demonstrate that the carbon isotopic signal of mid-depth waters evolved differently from deep waters in the South Atlantic sector of the Southern Ocean during the Pleistocene. Deep sites (>3700 m) exhibit large glacial-to-interglacial variations in benthic d13C, whereas the amplitude of the d1...
Published in: | Geochemistry, Geophysics, Geosystems |
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American Geophysical Union and the Geochemical Society
2003
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Online Access: | https://hdl.handle.net/1956/376 https://doi.org/10.1029/2002gc000367 |
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ftunivbergen:oai:bora.uib.no:1956/376 2023-05-15T18:24:04+02:00 Pleistocene vertical carbon isotope and carbonate gradients in the South Atlantic sector of the Southern Ocean Hodell, David A. Venz, K. A. Charles, Christopher D. Ninnemann, Ulysses Silas 2003-01-10 52168 bytes 137 bytes 1161270 bytes text/plain application/pdf https://hdl.handle.net/1956/376 https://doi.org/10.1029/2002gc000367 eng eng American Geophysical Union and the Geochemical Society urn:issn:1525-2027 https://hdl.handle.net/1956/376 https://doi.org/10.1029/2002gc000367 Copyright 2003 by the American Geophysical Union Geochemistry, geophysics, geosystems 4 1 Peer reviewed Journal article 2003 ftunivbergen https://doi.org/10.1029/2002gc000367 2023-03-14T17:40:31Z We demonstrate that the carbon isotopic signal of mid-depth waters evolved differently from deep waters in the South Atlantic sector of the Southern Ocean during the Pleistocene. Deep sites (>3700 m) exhibit large glacial-to-interglacial variations in benthic d13C, whereas the amplitude of the d13C signal at Site 1088 (2100 m water depth) is small. Unlike the deep sites, at no time during the Pleistocene were benthic d13C values at Site 1088 lower than those of the deep Pacific. Reconstruction of intermediate-todeep d13C gradients (D13CI-D) supports the existence of a sharp chemocline between 2100 and 2700 m during most glacial stages of the last 1.1 myr. This chemical divide in the glacial Southern Ocean separated well-ventilated water above 2500 m from poorly ventilated water below. The D13CI-D signal parallels the Vostok atmospheric pCO2 record for the last 400 kyr, lending support to physical models that invoke changes in Southern Ocean deep water ventilation as a mechanism for changing atmospheric pCO2. The emergence of a strong 100-kyr cycle in D13CI-D during the mid-Pleistocene supports a change in vertical fractionation and deep-water ventilation rates in the Southern Ocean, and is consistent with possible CO2- forcing of this climate transition. Components: 7562 words, 14 figures, 2 tables. publishedVersion Article in Journal/Newspaper Southern Ocean University of Bergen: Bergen Open Research Archive (BORA-UiB) Pacific Southern Ocean Geochemistry, Geophysics, Geosystems 4 1 1 19 |
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Open Polar |
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University of Bergen: Bergen Open Research Archive (BORA-UiB) |
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ftunivbergen |
language |
English |
description |
We demonstrate that the carbon isotopic signal of mid-depth waters evolved differently from deep waters in the South Atlantic sector of the Southern Ocean during the Pleistocene. Deep sites (>3700 m) exhibit large glacial-to-interglacial variations in benthic d13C, whereas the amplitude of the d13C signal at Site 1088 (2100 m water depth) is small. Unlike the deep sites, at no time during the Pleistocene were benthic d13C values at Site 1088 lower than those of the deep Pacific. Reconstruction of intermediate-todeep d13C gradients (D13CI-D) supports the existence of a sharp chemocline between 2100 and 2700 m during most glacial stages of the last 1.1 myr. This chemical divide in the glacial Southern Ocean separated well-ventilated water above 2500 m from poorly ventilated water below. The D13CI-D signal parallels the Vostok atmospheric pCO2 record for the last 400 kyr, lending support to physical models that invoke changes in Southern Ocean deep water ventilation as a mechanism for changing atmospheric pCO2. The emergence of a strong 100-kyr cycle in D13CI-D during the mid-Pleistocene supports a change in vertical fractionation and deep-water ventilation rates in the Southern Ocean, and is consistent with possible CO2- forcing of this climate transition. Components: 7562 words, 14 figures, 2 tables. publishedVersion |
format |
Article in Journal/Newspaper |
author |
Hodell, David A. Venz, K. A. Charles, Christopher D. Ninnemann, Ulysses Silas |
spellingShingle |
Hodell, David A. Venz, K. A. Charles, Christopher D. Ninnemann, Ulysses Silas Pleistocene vertical carbon isotope and carbonate gradients in the South Atlantic sector of the Southern Ocean |
author_facet |
Hodell, David A. Venz, K. A. Charles, Christopher D. Ninnemann, Ulysses Silas |
author_sort |
Hodell, David A. |
title |
Pleistocene vertical carbon isotope and carbonate gradients in the South Atlantic sector of the Southern Ocean |
title_short |
Pleistocene vertical carbon isotope and carbonate gradients in the South Atlantic sector of the Southern Ocean |
title_full |
Pleistocene vertical carbon isotope and carbonate gradients in the South Atlantic sector of the Southern Ocean |
title_fullStr |
Pleistocene vertical carbon isotope and carbonate gradients in the South Atlantic sector of the Southern Ocean |
title_full_unstemmed |
Pleistocene vertical carbon isotope and carbonate gradients in the South Atlantic sector of the Southern Ocean |
title_sort |
pleistocene vertical carbon isotope and carbonate gradients in the south atlantic sector of the southern ocean |
publisher |
American Geophysical Union and the Geochemical Society |
publishDate |
2003 |
url |
https://hdl.handle.net/1956/376 https://doi.org/10.1029/2002gc000367 |
geographic |
Pacific Southern Ocean |
geographic_facet |
Pacific Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Geochemistry, geophysics, geosystems 4 1 |
op_relation |
urn:issn:1525-2027 https://hdl.handle.net/1956/376 https://doi.org/10.1029/2002gc000367 |
op_rights |
Copyright 2003 by the American Geophysical Union |
op_doi |
https://doi.org/10.1029/2002gc000367 |
container_title |
Geochemistry, Geophysics, Geosystems |
container_volume |
4 |
container_issue |
1 |
container_start_page |
1 |
op_container_end_page |
19 |
_version_ |
1766204360608448512 |