EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Eccentricity-paced ice sheet variability and obliquity-driven bottom-water changes during the Oligocene-Miocene

Tim van Peer1, Victoria Taylor1, Diederik Liebrand1,2, Swaantje Brzelinski3, Iris Möbius4, André Bornemann5, Oliver Friedrich3, Steven Bohaty1, Chuang Xuan1, Peter Lippert6, and Paul Wilson1
Tim van Peer et al.
  • 1National Oceanography Centre Southampton, University of Southampton, Southampton, United Kingdom (
  • 2MARUM – Center for Marine Environmental Science, University of Bremen, Bremen, Germany
  • 3Institute of Earth Sciences, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
  • 4Institute of Geosciences, Goethe-University Frankfurt, Frankfurt, Germany
  • 5Federal Institute for Geosciences and Natural Resources, Hannover, Germany
  • 6Department of Geology & Geophysics, University of Utah, Salt Lake City, USA

Variations in solar insolation exert a fundamental control on the high-latitude climate–cryosphere system. Controversy, however, exists about the relative importance of orbital eccentricity versus axial tilt (obliquity) in driving pre-Quaternary Antarctic ice sheet variability. This problem is particularly acute during the late Oligocene-to-early Miocene interval (Oligo-Miocene, ~27-21 Ma), because several benthic foraminiferal oxygen isotopes (δ18O) records show strong pacing by obliquity, while others primarily show eccentricity pacing. The differences in orbital pacing are impossible to reconcile with the globally congruent imprint of ice volume on benthic δ18O on orbital time scales. Here we present a new astronomically tuned δ18O record generated at Integrated Ocean Drilling Program (IODP) Site U1406 (north-western Atlantic Ocean), a key area in modern-day thermohaline circulation. Clear imprints of both obliquity and eccentricity on the δ18O record are observed at Site U1406 throughout the study interval, irrespective of changes in sedimentation rate. The eccentricity variations at Site U1406 are remarkably similar to those seen in all other δ18O records, suggesting that eccentricity exerts a strong control on the high-latitude climate–cryosphere system via the modulation of the precession cycle. In contrast, the δ18O sensitivity to obliquity is globally variable, suggesting the influence of temperature in different bottom-water masses.

How to cite: van Peer, T., Taylor, V., Liebrand, D., Brzelinski, S., Möbius, I., Bornemann, A., Friedrich, O., Bohaty, S., Xuan, C., Lippert, P., and Wilson, P.: Eccentricity-paced ice sheet variability and obliquity-driven bottom-water changes during the Oligocene-Miocene, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15256,, 2020