Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies
Earths mightiest ocean current, the Antarctic Circumpolar Current (ACC), regulates the exchange of heat and carbon between the ocean and the atmosphere, and influences vertical ocean structure, deep-water production and the global distribution of nutrients and chemical tracers. The eastward-flowing...
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ftunivtasecite:oai:ecite.utas.edu.au:102143 2023-05-15T14:03:25+02:00 Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies Scher, HD Whittaker, JM Williams, SE Latimer, JC Kordesch, WEC Delaney, ML 2015 https://doi.org/10.1038/nature14598 http://www.ncbi.nlm.nih.gov/pubmed/26223626 http://ecite.utas.edu.au/102143 en eng Nature Publishing Group http://dx.doi.org/10.1038/nature14598 http://purl.org/au-research/grants/arc/DE140100376 Scher, HD and Whittaker, JM and Williams, SE and Latimer, JC and Kordesch, WEC and Delaney, ML, Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies, Nature, 523, (7562) pp. 580-583. ISSN 0028-0836 (2015) [Refereed Article] http://www.ncbi.nlm.nih.gov/pubmed/26223626 http://ecite.utas.edu.au/102143 Earth Sciences Geology Tectonics Refereed Article PeerReviewed 2015 ftunivtasecite https://doi.org/10.1038/nature14598 2019-12-13T22:03:45Z Earths mightiest ocean current, the Antarctic Circumpolar Current (ACC), regulates the exchange of heat and carbon between the ocean and the atmosphere, and influences vertical ocean structure, deep-water production and the global distribution of nutrients and chemical tracers. The eastward-flowing ACC occupies a unique circumglobal pathway in the Southern Ocean that was enabled by the tectonic opening of key oceanic gateways during the break-up of Gondwana (for example, by the opening of the Tasmanian Gateway, which connects the Indian and Pacific oceans). Although the ACC is a key component of Earths present and past climate system, the timing of the appearance of diagnostic features of the ACC (for example, low zonal gradients in water-mass tracer fields is poorly known and represents a fundamental gap in our understanding of Earth history. Here we show, using geophysically determined positions of continentocean boundaries that the deep Tasmanian Gateway opened 33.5 1.5 million years ago (the errors indicate uncertainty in the boundary positions). Following this opening, sediments from Indian and Pacific cores recorded Pacific-type neodymium isotope ratios, revealing deep westward flow equivalent to the present-day Antarctic Slope Current. We observe onset of the ACC at around 30 million years ago, when Southern Ocean neodymium isotopes record a permanent shift to modern IndianAtlantic ratios. Our reconstructions of ocean circulation show that massive reorganization and homogenization of Southern Ocean water masses coincided with migration of the northern margin of the Tasmanian Gateway into the mid-latitude westerly wind band, which we reconstruct at 64 S, near to the northern margin. Onset of the ACC about 30 million years ago coincided with major changes in global ocean circulation and probably contributed to the lower atmospheric carbon dioxide levels that appear after this time. Article in Journal/Newspaper Antarc* Antarctic Southern Ocean eCite UTAS (University of Tasmania) Antarctic Southern Ocean The Antarctic Pacific Indian Nature 523 7562 580 583 |
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eCite UTAS (University of Tasmania) |
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Earth Sciences Geology Tectonics |
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Earth Sciences Geology Tectonics Scher, HD Whittaker, JM Williams, SE Latimer, JC Kordesch, WEC Delaney, ML Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies |
topic_facet |
Earth Sciences Geology Tectonics |
description |
Earths mightiest ocean current, the Antarctic Circumpolar Current (ACC), regulates the exchange of heat and carbon between the ocean and the atmosphere, and influences vertical ocean structure, deep-water production and the global distribution of nutrients and chemical tracers. The eastward-flowing ACC occupies a unique circumglobal pathway in the Southern Ocean that was enabled by the tectonic opening of key oceanic gateways during the break-up of Gondwana (for example, by the opening of the Tasmanian Gateway, which connects the Indian and Pacific oceans). Although the ACC is a key component of Earths present and past climate system, the timing of the appearance of diagnostic features of the ACC (for example, low zonal gradients in water-mass tracer fields is poorly known and represents a fundamental gap in our understanding of Earth history. Here we show, using geophysically determined positions of continentocean boundaries that the deep Tasmanian Gateway opened 33.5 1.5 million years ago (the errors indicate uncertainty in the boundary positions). Following this opening, sediments from Indian and Pacific cores recorded Pacific-type neodymium isotope ratios, revealing deep westward flow equivalent to the present-day Antarctic Slope Current. We observe onset of the ACC at around 30 million years ago, when Southern Ocean neodymium isotopes record a permanent shift to modern IndianAtlantic ratios. Our reconstructions of ocean circulation show that massive reorganization and homogenization of Southern Ocean water masses coincided with migration of the northern margin of the Tasmanian Gateway into the mid-latitude westerly wind band, which we reconstruct at 64 S, near to the northern margin. Onset of the ACC about 30 million years ago coincided with major changes in global ocean circulation and probably contributed to the lower atmospheric carbon dioxide levels that appear after this time. |
format |
Article in Journal/Newspaper |
author |
Scher, HD Whittaker, JM Williams, SE Latimer, JC Kordesch, WEC Delaney, ML |
author_facet |
Scher, HD Whittaker, JM Williams, SE Latimer, JC Kordesch, WEC Delaney, ML |
author_sort |
Scher, HD |
title |
Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies |
title_short |
Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies |
title_full |
Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies |
title_fullStr |
Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies |
title_full_unstemmed |
Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies |
title_sort |
onset of antarctic circumpolar current 30 million years ago as tasmanian gateway aligned with westerlies |
publisher |
Nature Publishing Group |
publishDate |
2015 |
url |
https://doi.org/10.1038/nature14598 http://www.ncbi.nlm.nih.gov/pubmed/26223626 http://ecite.utas.edu.au/102143 |
geographic |
Antarctic Southern Ocean The Antarctic Pacific Indian |
geographic_facet |
Antarctic Southern Ocean The Antarctic Pacific Indian |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_relation |
http://dx.doi.org/10.1038/nature14598 http://purl.org/au-research/grants/arc/DE140100376 Scher, HD and Whittaker, JM and Williams, SE and Latimer, JC and Kordesch, WEC and Delaney, ML, Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies, Nature, 523, (7562) pp. 580-583. ISSN 0028-0836 (2015) [Refereed Article] http://www.ncbi.nlm.nih.gov/pubmed/26223626 http://ecite.utas.edu.au/102143 |
op_doi |
https://doi.org/10.1038/nature14598 |
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Nature |
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523 |
container_issue |
7562 |
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580 |
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583 |
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1766274066590728192 |