Abstract
The conventional model linking large igneous provinces (LIPs) to atmospheric CO(2) concentrations (pCO(2)) predicts elevated CO(2) during volcanic emplacement, leading to biotic crises. However, this generalization requires testing. Here, we reconstruct pCO(2) variations throughout the Emeishan LIP emplacement (~260 Ma) using carbon isotopes from chlorophyll-derived compounds. Our high-resolution record reveals that pCO(2) declined from ~ 700 ppm to ~ 350 ppm during the early and main flood basalt phases, then increased during subsequent silicic eruptions. This pattern coincides with pre-eruptive crustal uplift driven by mantle plume impingement. We propose that CO(2) consumption associated with enhanced erosion and weathering of kilometer-thick Yangtze craton carbonates from regional uplift might have temporarily exceeded the CO(2) contribution from magmatic degassing. This is supported by geochemical data indicating that the Emeishan basalt is particularly CO(2)-poor. Our findings demonstrate that LIP environmental impact begins before the main eruptive phase, highlighting that tectonic-magmatic interactions can produce more complex CO(2) patterns than previously recognized. This may explain why some LIPs caused extinctions, whereas others did not.