CLUMPED ISOTOPE ANALYSIS OF THE CRETACEOUS-PALEOGENE MASS EXTINCTION LINKED TO VOLCANICALLY INDUCED GLOBAL WARMING

Understanding the role of climate in past mass extinction events provides important context regarding the impacts of anthropogenic climate change on the modern biosphere. At the end of the Maastrichtian Age (~66 Ma), the Cretaceous-Paleogene (K-Pg) mass extinction wiped out ~70% of species, a rate comparable to projections of extinction resulting from modern global warming. Ambiguity persists concerning the cause of the K-Pg mass extinction due to two significant geological events dating very closely to the K-Pg boundary: the main eruptions of the Deccan Traps volcanic province and the Chicxulub asteroid impact. Although the majority of the extinction likely occurred at the time of asteroid impact, there is increasing evidence showing that global warming driven by increasing atmospheric CO₂ at the onset of the most intense phase of Deccan volcanic eruptions may have destabilized ecosystems and set the stage for amplified extinction when the asteroid hit. Here we apply clumped isotope paleothermometry to Maastrichtian-age fossil shells from the ENCI Quarry in the Southeast Netherlands (the type section of the Maastrichtian interval) to reconstruct changing temperatures preceding the K-Pg extinction. In addition, the clumped isotope method allows for independent reconstruction of the oxygen isotopic composition of seawater, which will be related to regional changes in the hydrological conditions, sea level fluctuations, and/or variations in connectivity or isolation of this basin. This study will reveal environmental changes in an important region, broadening understanding of both the local and global consequences of rising atmospheric CO₂ in relation to mass extinction events.