CHICXULUB AS A TESTING GROUND FOR MODELS AND THEORIES: TRIBUTE TO PROF. H. JAY MELOSH

From crater morphology to acoustic fluidization, H. Jay Melosh literally wrote the book on impact cratering as a geologic process (Melosh, 1989) and was working on a second edition at the time of his death. Since its identification through gravity data, confirmation through proximal ejecta and cores, and determination of structure through seismic data, he was a constant proponent of using the Chicxulub impact structure as a natural laboratory. His was a strong and steady voice regarding what aspects would be most important to investigate at Chicxulub whether through geophysical images or a drill bit, and the community is indebted to his scientific legacy while maintaining space for continued scientific discourse. Here, we detail key ideas about impact cratering processes that we have been able to observe or investigate at Chicxulub which were advocated for by Prof. Melosh. Processes including acoustic fluidization, gravitational collapse of central uplifts, crater modifications from transient to final crater morphology, changes in physical properties, and formation of peak rings all have been examined using geophysical and drilling data at Chicxulub with Melosh having run the gambit of roles from proponent to co-author to reviewer. Remarkably, the majority of his physics based and hydrocode modeled insights were either confirmed or proved foundational for an evolution of thought, over the last 30 years of research at the crater.