Eocene Cooling Linked to Early Flow across the Tasmanian Gateway

Authors

Peter K. Bijl, Utrecht UniversityFollow
James Bendle, University of BirminghamFollow
Steven M. Bohaty, University of SouthamptonFollow
Jörg Pross, Universitat HeidelbergFollow
Stefan Schouten, NIOZ Royal Netherlands Institute of Sea ResearchFollow
Lisa Tauxe, Scripps Institute of OceanographyFollow
Catherine E. Stickley, University of TromsøFollow
Robert McKay, Victoria University of WellingtonFollow
Ursula Röhl, MARUM Center for Marine Environmental Sciences BremenFollow
M. P. Olney, University of South FloridaFollow
Appy Sluijs, Utrecht UniversityFollow
Carlota Escutia, Universidad de GranadaFollow
Henk Brinkhuis, Utrecht UniversityFollow

Document Type

Article

Publication Date

2013

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.

Comments

Edited by Mark H. Thiemens, University of California, San Diego, La Jolla, CA, and approved April 23, 2013 (received for review November 30, 2012)

MSU Digital Commons Citation

Bijl, Peter K.; Bendle, James; Bohaty, Steven M.; Pross, Jörg; Schouten, Stefan; Tauxe, Lisa; Stickley, Catherine E.; McKay, Robert; Röhl, Ursula; Olney, M. P.; Sluijs, Appy; Escutia, Carlota; and Brinkhuis, Henk, "Eocene Cooling Linked to Early Flow across the Tasmanian Gateway" (2013). Department of Earth and Environmental Studies Faculty Scholarship and Creative Works. 47.
https://digitalcommons.montclair.edu/earth-environ-studies-facpubs/47

Published Citation

Bijl, P. K., Bendle, J. A. P., Bohaty, S. M., Pross, J., Schouten, S., Tauxe, L., . . . Expedition, S. (2013). Eocene cooling linked to early flow across the Tasmanian Gateway. Proceedings of the National Academy of Sciences of the United States of America, 110(24), 9645-9650. doi:10.1073/pnas.1220872110