Continental geological evidence for Solar System chaotic behavior in the Late Cretaceous

The Earth's geologic record of Milankov-itch cycles closely tracks Solar System solu-tions for the past 50 million years. Prior to 50 million years ago (Ma), however, the solu-tions lose accuracy rapidly due to chaotic behavior of the Solar System. Here we recon-struct a 10.173 million year-long record from 82.358 Ma to 92.531 Ma of Earth's orbital parameters from a continental lacustrine sequence in the Songliao Basin, China, con-strained by four in situ high-resolution radio-isotopic U-Pb ages and magnetic reversal stra-tigraphy. Analysis of thorium and ostracode shell abundance records from the Songliao Basin reveal evidence for two chaotic secular resonance transitions in the orbital motions of Earth and Mars from 85.2 Ma to 91.55 Ma. The evidence validates similar observations in western North American marine stratigra-phy. A unique phasing between the observed orbital eccentricity and obliquity modulations may explain the anoxic events that occurred in both marine and continental environments during this time. Taken together, the conti-nental and marine stratigraphic evidence demonstrates a strong global reach of Late Cretaceous Milankovitch cycles, and provides an important constraint on Solar System cha-oticity and the calculation of accurate orbital solutions prior to 50 Ma.

Automated summary

By analyzing a continental lacustrine sequence in the Songliao Basin, China, a 10.173 million year-long record of Earth's orbital parameters from 82.358 Ma to 92.531 Ma was reconstructed. It was found that there were two chaotic secular resonance transitions in the orbital motions of Earth and Mars from 85.2 Ma to 91.55 Ma, which may explain the occurrence of anoxic events in both marine and continental environments during this time.