Deccan volcanism caused coupled pCO₂ and terrestrial temperature rises, and pre-impact extinctions in northern China

Evaluating the terrestrial climate record provides a critical test of the roles of Chicxulub impact and Deccan Traps volcanism during the Cretaceous-Paleogene (K-Pg) mass extinction. Most evidence came from marine records, but our new clumped isotopes data from paleosol carbonates in the Songliao Basin provide a terrestrial climate history from northern China. This reveals there was a pre-impact warming caused by the onset of Deccan Traps volcanism, whereas the following short-term cooling then another warming episode were likely caused by Chicxulub impact and post-boundary volcanism. Our study suggests that the pCO₂ levels were probably the main control on the latest Cretaceous cooling and the climatic fluctuations across the K-Pg boundary interval in northern China. In the Songliao Basin, the pre-impact Deccan Traps volcanism links to losses of half of the lacustrine algae species (charophytes) and almost all of the lacustrine ostracodes; this suggests that the Deccan Traps volcanism had already destabilized the ecosystem and caused extinctions prior to the Chicxulub impact.