Terrestrial evidence for volcanogenic sulfate-driven cooling event ~30 kyr before the Cretaceous-Paleogene mass extinction

Abstract

Funding: The study was funded by UK Natural Environment Research Council grant NE/S002324/1 awarded to R.M.J., S.K.L., G.D.P., and B.E.v.D. L.K.O. is supported by the Netherlands Earth System Science Centre (grant no. 024.002.001). T.R.L. is supported by the National Science Foundation (NSF-FRES-2317666).Alongside the Chicxulub meteorite impact, Deccan volcanism is considered a primary trigger for the Cretaceous- Paleogene (K-Pg) mass extinction. Models suggest that volcanic outgassing of carbon and sulfur - potent environmental stressors - drove global temperature change, but the relative timing, duration, and magnitude of such change remains uncertain. Here, we use the organic paleothermometer MBT'5me and the carbon-isotope composition of two K-Pg-spanning lignites from the western Unites States, to test models of volcanogenic air temperature change in the ~100 kyr before the mass extinction. Our records show long-term warming of ~3°C, probably driven by Deccan CO2 emissions, and reveal a transient (<10 kyr) ~5°C cooling event, coinciding with the peak of the Poladpur "pulse" of Deccan eruption ~30 kyr before the K-Pg boundary. This cooling was likely caused by the aerosolization of volcanogenic sulfur. Temperatures returned to pre-event values before the mass extinction, suggesting that, from the terrestrial perspective, volcanogenic climate change was not the primary cause of K-Pg extinction.Peer reviewe