Chicxulub impact predates the K-T boundary mass extinction

doi:10.1073/pnas.0400396101

Chicxulub impact predates the K-T boundary mass extinction

^*Department of Geosciences, Princeton University, Princeton, NJ 08540; ^‡Institute of Geology, University of Neuchatel, 2007 Neuchatel, Switzerland; ^§Geological Institute and ^**Institute for Mineralogy and Geochemistry, University of Karlsruhe, D-76128 Karlsruhe, Germany; ^¶Laboratoire des Sciences du Climat et l'Environnement, Unité Mixte de Recherche Centre National de la Recherche Scientifique-Commissariat à l'Energie Atomique, Bât 12, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France; and ^∥Instituto de Geofisica, Universidad Nacional Autonóma de México, Ciudad Universitaria, Mexico City, CP 04510, Mexico

Communicated by W. Jason Morgan, Princeton University, Princeton, NJ, January 20, 2004 (received for review October 3, 2003)

Abstract

Since the early l990s the Chicxulub crater on Yucatan, Mexico, has been hailed as the smoking gun that proves the hypothesis that an asteroid killed the dinosaurs and caused the mass extinction of many other organisms at the Cretaceous-Tertiary (K-T) boundary 65 million years ago. Here, we report evidence from a previously uninvestigated core, Yaxcopoil-1, drilled within the Chicxulub crater, indicating that this impact predated the K-T boundary by ≈300,000 years and thus did not cause the end-Cretaceous mass extinction as commonly believed. The evidence supporting a pre-K-T age was obtained from Yaxcopoil-1 based on five independent proxies, each with characteristic signals across the K-T transition: sedimentology, biostratigraphy, magnetostratigraphy, stable isotopes, and iridium. These data are consistent with earlier evidence for a late Maastrichtian age of the microtektite deposits in northeastern Mexico.

Footnotes

↵ † To whom correspondence should be addressed. E-mail: gkeller{at}princeton.edu.
Abbreviations: K-T, Cretaceous-Tertiary; ky, thousand years; XRD, x-ray diffraction; Yax-1, Yaxcopoil-1.
↵ †† Stinnesbeck, W., Keller, G., Adatte, T. & Stueben, D. (2003) Geophys. Res. Abstr. 5, 10868.
↵ ‡‡ Smit, J., Dressler, B. O., Buffler, R., Moran, D., Sharpton, V. L., Stoeffler, D., Urrutia, J. & Morgan, J. (2003) Geophys. Res. Abstr. 5, 06498.