T139 Impact Cratering: Geologic, Geochemical, and Geophysical Signatures on the Terrestrial Planets

Monday, 5 November 2018
1:30 PM - 5:30 PM
Room 235

INSIGHTS INTO IMPACT PROCESSES AND EXTINCTION MECHANISMS FROM IODP-ICDP CHICXULUB CRATER DRILLING

Paper number: T139-5
Program: Technical Sessions
Time: 2:35 PM – 2:55 PM

Authors

Abstract

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. Here, we highlight the current findings and suggest the next phase of investigations set up by Expedition 364. Key results in terms of impact crater processes include: 1) dynamic collapse model for large impact crater formation essentially validated; 2) unprecedented insights into deformation mechanisms imparted by shock and release as well as cratering at variable length and time scales, collectively corroborating the acoustic fluidization hypothesis; 3) direct measurements and analyses of shocked target rocks to provide an explanation for the large reductions in density and enhancements in porosity generated by impacts; and 4) sampling and mapping of >100 m of high porosity suevite and impact melt rock as a case study of cratering processes. These cores also provided greater understanding of how impact cratering can affect life positively and negatively: 1) long term but heterogeneous hydrothermal system generated by the impact, 2) colonization of impactites by thermophiles, 3) rapid recovery of marine life within the flooded Chicxulub crater basin, 4) direct evidence of impact tsunami and wildfires, and 5) evidence of significant sulfate aerosol production from the impact site affecting the global environment, possibly causing the delay in terrestrial vegetation recovery. Future research on Exp. 364 data will focus on kinematics of deformation, modeling the hydrothermal system, impact thermochronology, examining the 3D complexity of impactite deposition, modeling the impact tsunami with updated paleogeography, identification of impactor signatures, geochemical insights into oceanographic effects of ejecta, and using the Chicxulub basin to study Paleocene and Eocene environment and ecology among other topics. Lastly, we’ve identified additional drilling targets to further address the above questions based on the remarkably rich dataset provided by this single offshore drill site.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-319280

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