Cancellation of the precessional cycle in δ18O records during the Early Pleistocene
- 1Department of Earth Science, University of Bergen and the Bjerknes Centre for Climate Research, Bergen, Norway
- 2Centre for Earth Evolution and Dynamics (CEED), Department of Geosciences, University of Oslo, Norway
- 3Geophysical Institute, University of Bergen and the Bjerknes Centre for Climate Research, Bergen, Norway
- 4Institute for Geophysics, Jackson School of Geosciences, the University of Texas at Austin, Austin, Texas
- 5Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
The dominant pacing of glacial‐interglacial cycles in deep‐ocean δ18O records changed substantially during the Mid‐Pleistocene Transition. The precessional cycle (∼23 ky) is absent during the Early Pleistocene, which we show can be explained by cancellation of the hemispherically anti‐phased precessional cycle in the Early Pleistocene interior ocean. Such cancellation develops due to mixing of North Atlantic and Southern Ocean δ18O signals at depth, and shows characteristic spatial patterns. We explore the cancellation potential for different North Atlantic and Southern Ocean deep‐water source δ18O values using a tracer transport ocean model. Cancellation of precession occurs for all signal strengths and is widespread for a signal strength typical for the Early Pleistocene. Early Pleistocene precessional power is therefore likely incompletely archived in deep‐sea δ18O records, concealing the true periodicity of the glacial cycles in the two hemispheres.
How to cite: Nisancioglu, K., Morée, A., Sun, T., Straume, E., and Gebbie, G.: Cancellation of the precessional cycle in δ18O records during the Early Pleistocene, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14370, https://doi.org/10.5194/egusphere-egu21-14370, 2021.
