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 and Welsh, Kevin (2013) Eocene cooling linked to early flow across the Tasmanian Gateway. Proceedings of the National Acadamy of Sciences of the United States of America, 110 24: 9645-9650. doi:10.1073/pnas.1220872110

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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
Title Eocene cooling linked to early flow across the Tasmanian Gateway
Journal name Proceedings of the National Acadamy of Sciences of the United States of America   Check publisher's open access policy
ISSN 0027-8424
Publication date 2013-06-11
Sub-type Article (original research)
DOI 10.1073/pnas.1220872110
Open Access Status Not yet assessed
Volume 110
Issue 24
Start page 9645
End page 9650
Total pages 6
Editor Mark H. Thiemens
Place of publication Washington, DC, United States
Publisher National Academy of Sciences
Language eng
Formatted abstract
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 ∼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 °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.
Keyword Climate cooling
Dinoflagellate cysts
Organic palaeothermometry
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Earth Sciences Papers
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Citation counts: TR Web of Science Citation Count  Cited 63 times in Thomson Reuters Web of Science Article | Citations
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Created: Wed, 18 Dec 2013, 01:13:30 EST by Ashleigh Paroz on behalf of School of Earth Sciences