The Eocene–Oligocene Transition (EOT, ~34 Ma), is marked by the rapid development of semi-permanent Antarctic ice-sheet1.
Foraminiferal stable oxygen isotopes (δ18O) as well as Mg/Ca and other indicators (e.g. ice-rafted debris) indicate the development
of permanent glaciation that potentially coincides with ~2.5 °Cdeep-sea cooling2. However, due to the nature of the δ18O proxy,
uncertainties in the Mg/Ca concentrations of the palaeo-seawater, and calibration extrapolation/saturation to/at higher temperatures
for organic proxies, it remains unclear how sea surface temperature (SST) changed across the EOT.
In this study, we apply clumped-isotope palaeothermometry to well-preserved planktic foraminifera from the drift sediments of IODP Site 1411, Newfoundland, across four intervals bracketing the EOT. Initial findings indicate minor cooling across the interval, with absolute temperatures that are significantly lower than those reconstructed using other proxies3, a discrepancy that warrants further research.
1- Coxall, H. K., Pearson, P. N. (2007). The Eocene-Oligocene transition. Deep Time Perspectives on Climate Change: Marrying the Signal From Computer Models and Biological Proxies, p. 351-387.
2- Lear, C. H., Bailey, T. R., Pearson, P. N., Coxall, H. K., Rosenthal, Y. (2008) Cooling and ice growth across the Eocene-Oligocene transition. Geology 36, p. 251–254.
3- Liu, Z., He, Y., Jiang, Y., Wang, H., Liu, W., Bohaty, S. M., Wilson, P. A. (2018). Transient temperature asymmetry between hemispheres in the Palaeogene Atlantic Ocean. Nature Geoscience, 11(9), p. 656.
Ilja Japhir Kocken (1), Kasper van der Veen (1), Inigo R. Müller (1), Anna Nele Meckler (2) & Martin Ziegler (1)
Utrecht University, The Netherlands (1); Unviersity of Bergen, Norway (2)