Physical characterization of a simulated impact-vapor plume using laser ablation of Chicxulub sediments

Abstract

An asteroid impacted the Yucatan carbonate platform in the Southern Gulf of Mexico about 66 million years ago. The ejecta and impact-vapor plume introduced massive amounts of gases and dust into the atmosphere causing major global environmental effects that led to the Cretaceous-Paleogene mass extinction. The physical parameters of the Chicxulub impact-vapor plume are not completely known and are important to constrain its evolution and the aftermath of the event. Here we reconstruct the impact-vapor plume by laser ablation of target sediments recovered from the Yaxcopoil-1 borehole in the Chicxulub impact crater. The ablation experiment was performed under a reconstructed late Cretaceous atmosphere composed of 0.16% CO2, 30% O2, and 69.84% N2 at 1000 ​mbar. The initial propagation velocities of the shockwave and impact-vapor plume were ~4.5 ​km ​s−1 and ~2.3 ​km ​s−1, respectively. The temperature and electron density of a simulated Chicxulub impact-vapor plume were determined using calcium emission lines. The initial temperature and electron density were estimated to be ~1.8(±0.1)×104 ​K and ~5.9(±0.7)×1017 ​cm−3, respectively. The plume expanded adiabatically with a specific heat ratio of 1.31 ​± ​0.03. Its initial pressure was computed to be ~103 ​bar. These parameters are required in gas dynamic codes to develop chemical models to study the evolution of the simulated impact-vapor plume and predict the fluxes and nature of gases, vapors and mineral phases injected in the atmosphere. Such chemical models will allow scaling from laboratory to planetary conditions to better constrain the chemical effects to the environment and the biosphere by the asteroid impact.