Dartmouth Events

Cenozoic Ocean Redox Evolution: A Uranium Isotope Perspective

Xiangli Wang

Agouron Institute Postdoctoral Fellow

The Cenozoic Era is characterized by large surface temperature fluctuations and active mountain-building events. Lower O₂ saturation concentration under higher temperature conditions and increased nutrient supply in the backdrop of active tectonic activity may have caused the ocean redox state to fluctuate, posing threat on marine organisms.

²³⁸U/²³⁵U measurement is an emerging redox proxy that can be used to track seawater redox conditions. Ferromanganese crusts provide a continuous Cenozoic seawater ²³⁸U/²³⁵U record, which remained unchanged throughout the Cenozoic, suggesting that the long-term ocean redox state has remained unchanged throughout the Cenozoic. P-N co-limitation may have contributed to the stabilization of the ocean redox state.