Dr. Sean Gulick, Jackson School of Geosciences, University of Texas at Austin

Thursday, January 27, 2022 in BE 241/ Zoom, 4-5PM

Life and Death by Impact: Drilling for Clues

Abstract: The most recent of Earth’s five largest mass extinction events occurred 66 Ma, coeval with the impact of a ~12 km asteroid, striking at ~60 degrees into what is today the Yucatán Peninsula, México, producing the ~200 km-wide Chicxulub crater. This impact, by some estimations, drove the extinction of 75% of life on Earth at the genus level including all non-avian dinosaurs.  Proposed kill mechanisms include thermal effects caused by the reentry of fast ejecta into Earth’s atmosphere, dust, soot, and sulfate aerosols reducing Earth’s solar insolation and ocean acidification. In 2016, 835 m of core was recovered from the Chicxulub impact structure through IODP-ICDP Expedition 364. Analyses done on these cores, downhole logs, and geophysical site survey data have led to a series of advancements to our understanding of impact cratering processes and to how the Chicxulub impact affected the Earth’s environment leading to the Cretaceous-Paleogene mass extinction. Key areas of discovery include: 1) clear evidence for origin of peak rings and crater dynamics in large impacts, 2) highest resolution record to date of impact processes within the crater include deposition of impactites and role of ocean resurge and tsunami, 3) rapid recovery of life at ground zero with a key niche being filled by cyanobacteria, and 4) development of a long lived hydrothermal system with astrobiological implications.

Bio: Research Professor Sean Gulick, his students, and colleagues are working on tectonic and climate interactions on continental margins, geohazards of subduction and transform faulting in active plate margins, and the geologic processes and environmental effects of the Cretaceous-Paleogene Chicxulub meteor impact and other impact craters. To test some key hypotheses of how glacial erosion can perturb tectonics in 2013 Sean served as co-chief on the Integrated Ocean Drilling Program (IODP) Expedition 341: Southeast Alaska tectonics and climate. In 2014, Sean led the seismic imaging in a multidisciplinary cruise to the unexplored Sabrina Coast shelf in East Antarctica. In 2016, Sean served as co-chief scientist on the joint International Ocean Discovery and Continental Drilling Programs Expedition 364: Drilling the K-Pg Chicxulub impact crater.

Sean lives on a small ranch in Sunset Valley Texas with his wife, Dr. Jennifer Jobst, and their horses, dogs, cats, and chickens. He competes in medieval jousting tournaments internationally and conducts medieval research as a hobby.

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