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doi:10.14379/iodp.sp.364.2016

International Ocean Discovery Program
Expedition 364 Scientific Prospectus

Chicxulub: drilling the K-Pg impact crater

In collaboration with the
International Continental Scientific Drilling Program1


Sean Gulick

Co-Chief Scientist

Institute for Geophysics

J.J. Pickle Research Campus, Building 196

10100 Burnet Road (R2200)

Austin TX 78758-4445

USA

sean@ig.utexas.edu

Joanna Morgan

Co-Chief Scientist

Department of Earth Science and

Engineering

Imperial College London

South Kensington Campus

London SW7 2AZ

United Kingdom

j.v.morgan@imperial.ac.uk

Claire L. Mellett

ESO Expedition Project Manager

British Geological Survey

Murchison House

West Mains Road

Edinburgh EH9 3LA

United Kingdom

cmell@bgs.ac.uk

Jaime Urrutia Fucugauchi

Mexican Scientific Coordinator

Institute of Geophysics

UNAM Board of Governors

National University of Mexico

Coyoacan 04510 Mexico City

Mexico

juf@geofisica.unam.mx

Published March 2016

See the full publication in PDF.

Abstract

The Chicxulub impact crater in Mexico is unique. It is the only known terrestrial impact structure that has been directly linked to a mass extinction event and the only terrestrial impact with a global ejecta layer. Of the three largest impact structures on Earth, Chicxulub is the best preserved. Chicxulub is also the only known terrestrial impact structure with an intact, unequivocal topographic “peak ring.” Chicxulub’s role in the Cretaceous/Paleogene (K-Pg) mass extinction and its exceptional state of preservation make it an important natural laboratory for the study of both large impact crater formation on Earth and other planets and the effects of large impacts on Earth’s environment and ecology. Our understanding of the impact process is far from complete, and despite more than 30 y of intense debate, we are still striving to answer the question as to why this impact was so catastrophic.

International Ocean Discovery Program (IODP) Expedition 364 proposes to core through the peak ring of the Chicxulub impact crater to investigate (1) the nature and formational mechanism of peak rings, (2) how rocks are weakened during large impacts, (3) the nature and extent of postimpact hydrothermal circulation, (4) the deep biosphere and habitability of the peak ring, and (5) the recovery of life in a sterile zone. Of additional interest is the transition through a rare midlatitude record of the Paleocene/Eocene Thermal Maximum (PETM); the composition and character of impact breccias, melt rocks, and peak-ring rocks; the sedimentology and stratigraphy of the Cenozoic sequence; and any observations from the core that would help us constrain the volume of dust and climatically active gases released into the stratosphere by this impact. Petrophysical property measurements on the core and wireline logs will be used to calibrate geophysical models, including seismic reflection data. Proposed drilling directly contributes to the IODP science plan initiatives (1) Deep Biosphere and the Subseafloor Ocean and (2) Environmental Change, Processes and Effects, in particular the environmental and biological perturbations caused by the Chicxulub impact.

Expedition 364 will be implemented as a mission-specific platform expedition to obtain subseabed samples and downhole logging measurements from the peak ring of the Chicxulub impact crater. The expedition aims to core a single borehole as deep as 1500 meters below seafloor (mbsf) to recover rock cores from above and into the Chicxulub impact crater preserved under the Yucatán continental shelf.


1Gulick, S., Morgan, J., and Mellett, C.L., 2016. Expedition 364 Scientific Prospectus: Chicxulub: drilling the K-Pg impact crater. International Ocean Discovery Program. http://dx.doi.org/​10.14379/​iodp.sp.364.2016