Periodic changes in the Cretaceous ocean and climate caused by marine redox see-saw
"Periodic changes in sediment composition are usually ascribed to insolation forcing controlled by Earth’s orbital parameters. During the Cretaceous Thermal Maximum at 97–91 Myr ago (Ma), a 37–50-kyr-long cycle that is generally believed to reflect obliquity forcing dominates the sediment record. [...]"
Source: Nature Geoscience
Authors: Klaus Wallmann et al.