BORON AND CARBON ISOTOPE CONSTRAINTS ON CO2 EMISSION PATTERNS DURING THE END-PERMIAN MASS EXTINCTION

The end-Permian mass extinction (EPME; ~252 Ma), known as the largest extinction event during the Phanerozoic Eon, provides an important case study to understand the impacts of climate change in the present. The warming associated with the EPME was likely triggered by the emissions of large quantities of CO₂ during the eruption of the voluminous Siberian Traps (ST) volcanism, which eliminated 80 to 90% of marine species and 70% of terrestrial species. However, the CO₂ emission patterns associated with the two eruption phases of the ST volcanism remain unclear. The study uses recently published boron isotopes from well-preserved brachiopod shells and bulk carbonates as constraints for ocean surface pH, and a global compilation of carbon isotopes from marine carbonates and algae biomarkers as constraints for the surface ocean δ¹³C to quantify the pattern of CO₂ emissions across the EPME. In doing so, the isotopic values of the carbon sources can be quantified with a unique solution with quantifiable uncertainties. Such isotopic and pH inversion was performed using the carbon-centric Grid ENabled Integrated Earth system models (cGENIE). The carbonate chemistry, weathering rates, nutrient conditions, and organic carbon burial rates were quantified as a result of these inversion experiments.