Tokyo Institute of Technology

Japan Agency for Marine-Earth Science and Technology

Graduate School of Science, The University of Tokyo

Toho University

Summary

Associate Professor Akira Ishikawa of the Department of Earth and Planetary Science, Faculty of Science, Tokyo Institute of Technology, Senior Staff Naotaka Tomioka of the Kochi Core Research Institute, JAMSTEC, Professor Kazuhisa Goto of the Graduate School of Science, The University of Tokyo, and Associate Professor Kosei Yamaguchi of Toho University are Professor Steven Goderis of the Free University of Brussels, In an international collaboration with Professor Steven Goderis of the Free University of Brussels and Dr. Minami Sato of the University of Padova, Italy, they conducted chemical analysis of an element (iridium) that is characteristic of asteroidal materials in excavated samples from the interior of Chichurubu Crater in Mexico, which formed at the Cretaceous/Paleogene boundary approximately 66 million years ago, and found that asteroidal materials were concentrated at the top of the impact-derived sedimentary material. The results of this research revealed that asteroidal material is concentrated in the uppermost part of the impact deposits.

The results of this study provide an important basis for precisely aligning the time axis of this impact site with the strata deposited around the Cretaceous/Paleogene boundary reported from around the world. In the future, it is expected that environmental changes before and after the extinction of the dinosaurs will be reconstructed in more detail by providing clues as to how materials scattered by a large-scale asteroid impact were dispersed throughout the Earth.

The research results were published in the international journal Science Advances on February 24, 2021 (EST).

Figure: The Myrtle used to drill the Chichurub Crater (courtesy of The University of Texas at Austin, Jackson School of Geosciences).

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