Volcanism-Driven Nonlinear Amplification of Precession-Scale Variability Triggered Mesoproterozoic Oxygenation

Mesoproterozoic oxygenation represents a critical step in the rise of complex life, yet the extent to which deep Earth processes and orbital forcing jointly regulated oxygen levels remains poorly constrained due to the scarcity of long, high-resolution chronological frameworks capable of resolving both processes. Here we present centimeter-scale aluminum (Al) and silicon (Si) records from the ~1.4 Ga Xiamaling Formation (North China Craton) and construct a ~20.7 Myr astronomical time scale (1412.8–1392.1 Ma) spanning a volcanism-influenced interval. Our records show that following ~1.4 Ga volcanism, long-term increases in weathering intensity and nutrient supply were accompanied by strongly amplified ~10-16 kyr precession-scale variability. Concurrently, the ~405 kyr long eccentricity signal was weakened, whereas ~100 kyr short eccentricity variability was enhanced. We infer that volcanism pushed the ocean–sediment system toward a near-threshold state, in which nonlinear responses to orbital forcing preferentially amplified high-frequency variability. In this volcanically sensitized state, precession paced alternations between silica-rich and organic-rich deposition, promoting efficient organic carbon burial and associated oxygenation. These results provide a new framework for nonlinear orbital responses of ocean–sediment systems in a greenhouse Earth lacking ice sheets, offering fresh insight into the mechanisms underlying Mesoproterozoic oxygenation.