Atmospheric CO<sub>2</sub> drawdown during the Emeishan flood basalt volcanism.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41748594.
- Also identified by DOI 10.1038/s41467-026-69600-z and PMC identifier 12946269.
- Licence recorded as CC BY-NC-ND.
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Abstract
The conventional model linking large igneous provinces (LIPs) to atmospheric CO<sub>2</sub> concentrations (pCO<sub>2</sub>) predicts elevated CO<sub>2</sub> during volcanic emplacement, leading to biotic crises. However, this generalization requires testing. Here, we reconstruct pCO<sub>2</sub> variations throughout the Emeishan LIP emplacement (~260 Ma) using carbon isotopes from chlorophyll-derived compounds. Our high-resolution record reveals that pCO<sub>2</sub> 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<sub>2</sub> consumption associated with enhanced erosion and weathering of kilometer-thick Yangtze craton carbonates from regional uplift might have temporarily exceeded the CO<sub>2</sub> contribution from magmatic degassing. This is supported by geochemical data indicating that the Emeishan basalt is particularly CO<sub>2</sub>-poor. Our findings demonstrate that LIP environmental impact begins before the main eruptive phase, highlighting that tectonic-magmatic interactions can produce more complex CO<sub>2</sub> patterns than previously recognized. This may explain why some LIPs caused extinctions, whereas others did not.