Astronomical forcing of a Middle Permian chert sequence in Chaohu, South China

- A Middle Permian chert-mudstone sequence is examined for astronomical forcing.
- Power in obliquity and precession frequency bands indicates insolation forcing.
- Insolation-forced equatorial upwelling drove oceanic radiolarian productivity.
- Glacio-eustacy increased mud flux when radiolarian productivity is low.
- A floating astronomical time scale of 4.7 myr calibrates middle Permian time.