Eocene cooling linked to early flow across the Tasmanian Gateway
The warmest global temperatures of the past 85 million years occurred during a prolonged greenhouse episode known as the Early Eocene Climatic Optimum (52-50 Ma). The Early Eocene Climatic Optimum terminated with a long-term cooling trend that culminated in continental-scale glaciation of Antarctica...
Published in: | Proceedings of the National Academy of Sciences |
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Online Access: | https://espace.library.uq.edu.au/view/UQ:319700 |
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ftunivqespace:oai:espace.library.uq.edu.au:UQ:319700 2023-05-15T13:49:28+02:00 Eocene cooling linked to early flow across the Tasmanian Gateway Bilj, Peter K. Bendle, James A. P. Bohtay, Steven M. Pross, Jörg Schouten, Stefan Tauxe, Lisa Stickley, Catherine E. McKay, Robert M. Rohl, Ursula Olney, Matthew Sluijs, Appy Escutia, Carlota Brinkhius, Henk Expedition 318 Scientists Welsh, Kevin Mark H. Thiemens 2013-06-11 https://espace.library.uq.edu.au/view/UQ:319700 eng eng National Academy of Sciences doi:10.1073/pnas.1220872110 issn:0027-8424 issn:1091-6490 orcid:0000-0002-4834-4190 86610110 Not set NE/I00646X/1 NE/H014616/1 NE/H020098/1 NE/J019801/1 PR 651/10 RO 1113/6 OCE 1058858 259627 NE/H025162/1 NE/I006257/1 NE/I00646X/2 1058858 1129101 Climate cooling Dinoflagellate cysts Organic palaeothermometry Paleoceanography Journal Article 2013 ftunivqespace https://doi.org/10.1073/pnas.1220872110 2020-12-15T00:54:37Z The warmest global temperatures of the past 85 million years occurred during a prolonged greenhouse episode known as the Early Eocene Climatic Optimum (52-50 Ma). The Early Eocene Climatic Optimum terminated with a long-term cooling trend that culminated in continental-scale glaciation of Antarctica from 34 Ma onward. Whereas early studies attributed the Eocene transition from greenhouse to icehouse climates to the tectonic opening of Southern Ocean gateways, more recent investigations invoked a dominant role of declining atmospheric greenhouse gas concentrations (e.g., CO2). However, the scarcity of field data has prevented empirical evaluation of these hypotheses. We present marine microfossil and organic geochemical records spanning the early-to-middle Eocene transition from the Wilkes Land Margin, East Antarctica. Dinoflagellate biogeography and sea surface temperature paleothermometry reveal that the earliest throughflow of a westbound Antarctic Counter Current began similar to 49-50 Ma through a southern opening of the Tasmanian Gateway. This early opening occurs in conjunction with the simultaneous onset of regional surface water and continental cooling (2-4 degrees C), evidenced by biomarker- and pollen-based paleothermometry. We interpret that the westbound flowing current flow across the Tasmanian Gateway resulted in cooling of Antarctic surface waters and coasts, which was conveyed to global intermediate waters through invigorated deep convection in southern high latitudes. Although atmospheric CO2 forcing alone would provide a more uniform middle Eocene cooling, the opening of the Tasmanian Gateway better explains Southern Ocean surface water and global deep ocean cooling in the apparent absence of (sub-) equatorial cooling. Article in Journal/Newspaper Antarc* Antarctic Antarctica East Antarctica Southern Ocean Wilkes Land The University of Queensland: UQ eSpace Antarctic East Antarctica Southern Ocean Wilkes Land ENVELOPE(120.000,120.000,-69.000,-69.000) Proceedings of the National Academy of Sciences 110 24 9645 9650 |
institution |
Open Polar |
collection |
The University of Queensland: UQ eSpace |
op_collection_id |
ftunivqespace |
language |
English |
topic |
Climate cooling Dinoflagellate cysts Organic palaeothermometry Paleoceanography |
spellingShingle |
Climate cooling Dinoflagellate cysts Organic palaeothermometry Paleoceanography Bilj, Peter K. Bendle, James A. P. Bohtay, Steven M. Pross, Jörg Schouten, Stefan Tauxe, Lisa Stickley, Catherine E. McKay, Robert M. Rohl, Ursula Olney, Matthew Sluijs, Appy Escutia, Carlota Brinkhius, Henk Expedition 318 Scientists Welsh, Kevin Eocene cooling linked to early flow across the Tasmanian Gateway |
topic_facet |
Climate cooling Dinoflagellate cysts Organic palaeothermometry Paleoceanography |
description |
The warmest global temperatures of the past 85 million years occurred during a prolonged greenhouse episode known as the Early Eocene Climatic Optimum (52-50 Ma). The Early Eocene Climatic Optimum terminated with a long-term cooling trend that culminated in continental-scale glaciation of Antarctica from 34 Ma onward. Whereas early studies attributed the Eocene transition from greenhouse to icehouse climates to the tectonic opening of Southern Ocean gateways, more recent investigations invoked a dominant role of declining atmospheric greenhouse gas concentrations (e.g., CO2). However, the scarcity of field data has prevented empirical evaluation of these hypotheses. We present marine microfossil and organic geochemical records spanning the early-to-middle Eocene transition from the Wilkes Land Margin, East Antarctica. Dinoflagellate biogeography and sea surface temperature paleothermometry reveal that the earliest throughflow of a westbound Antarctic Counter Current began similar to 49-50 Ma through a southern opening of the Tasmanian Gateway. This early opening occurs in conjunction with the simultaneous onset of regional surface water and continental cooling (2-4 degrees C), evidenced by biomarker- and pollen-based paleothermometry. We interpret that the westbound flowing current flow across the Tasmanian Gateway resulted in cooling of Antarctic surface waters and coasts, which was conveyed to global intermediate waters through invigorated deep convection in southern high latitudes. Although atmospheric CO2 forcing alone would provide a more uniform middle Eocene cooling, the opening of the Tasmanian Gateway better explains Southern Ocean surface water and global deep ocean cooling in the apparent absence of (sub-) equatorial cooling. |
author2 |
Mark H. Thiemens |
format |
Article in Journal/Newspaper |
author |
Bilj, Peter K. Bendle, James A. P. Bohtay, Steven M. Pross, Jörg Schouten, Stefan Tauxe, Lisa Stickley, Catherine E. McKay, Robert M. Rohl, Ursula Olney, Matthew Sluijs, Appy Escutia, Carlota Brinkhius, Henk Expedition 318 Scientists Welsh, Kevin |
author_facet |
Bilj, Peter K. Bendle, James A. P. Bohtay, Steven M. Pross, Jörg Schouten, Stefan Tauxe, Lisa Stickley, Catherine E. McKay, Robert M. Rohl, Ursula Olney, Matthew Sluijs, Appy Escutia, Carlota Brinkhius, Henk Expedition 318 Scientists Welsh, Kevin |
author_sort |
Bilj, Peter K. |
title |
Eocene cooling linked to early flow across the Tasmanian Gateway |
title_short |
Eocene cooling linked to early flow across the Tasmanian Gateway |
title_full |
Eocene cooling linked to early flow across the Tasmanian Gateway |
title_fullStr |
Eocene cooling linked to early flow across the Tasmanian Gateway |
title_full_unstemmed |
Eocene cooling linked to early flow across the Tasmanian Gateway |
title_sort |
eocene cooling linked to early flow across the tasmanian gateway |
publisher |
National Academy of Sciences |
publishDate |
2013 |
url |
https://espace.library.uq.edu.au/view/UQ:319700 |
long_lat |
ENVELOPE(120.000,120.000,-69.000,-69.000) |
geographic |
Antarctic East Antarctica Southern Ocean Wilkes Land |
geographic_facet |
Antarctic East Antarctica Southern Ocean Wilkes Land |
genre |
Antarc* Antarctic Antarctica East Antarctica Southern Ocean Wilkes Land |
genre_facet |
Antarc* Antarctic Antarctica East Antarctica Southern Ocean Wilkes Land |
op_relation |
doi:10.1073/pnas.1220872110 issn:0027-8424 issn:1091-6490 orcid:0000-0002-4834-4190 86610110 Not set NE/I00646X/1 NE/H014616/1 NE/H020098/1 NE/J019801/1 PR 651/10 RO 1113/6 OCE 1058858 259627 NE/H025162/1 NE/I006257/1 NE/I00646X/2 1058858 1129101 |
op_doi |
https://doi.org/10.1073/pnas.1220872110 |
container_title |
Proceedings of the National Academy of Sciences |
container_volume |
110 |
container_issue |
24 |
container_start_page |
9645 |
op_container_end_page |
9650 |
_version_ |
1766251418287603712 |