Clearing up the Chicxulub Vapor Cloud: Petrographic and geochemical analysis of uniquely preserved impact ejecta and their role in the end-Cretaceous mass extinction

The Chicxulub meteorite impact in Mexico was one of the most catastrophic events in the history of life on Earth. This impact happened ~66 million years ago and caused a rapid global climate change and the Cretaceous-Paleogene (K-Pg) mass extinction, marking the end of the dinosaurs. Nearly 40 years of K-Pg research has led to the hypothesis that shock-vaporization of the target rock played a key role in the environmental stress after the impact. However, major questions remain unanswered about the amount and types of products that were injected into the atmosphere, their transport and worldwide deposition, and their climatic and biotic effects.

This project is motivated by the recent discovery of two exceptional K-Pg ejecta sites ~3000 km north and south of the Chicxulub crater. In contrast to previous studied ejecta sites, these localities yield uniquely preserved glassy impact spherules. Studying their microtexture and
chemical and isotopic compositions, provides additional clues about the contribution of the target lithologies and the meteorite itself. Comparing these sites with proximal and distal ejecta data and new results from Chicxulub core material recently obtained by the IODP-ICDP project enables establishing a new model of vapor plume dynamics and will result in better estimates of the released climate-active gases. This is imperative to understand how the energy release by the impact was transferred to the Earth System and led to the mass extinction.