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EOS, TRANSACTIONS AMERICAN GEOPHYSICAL UNION, VOL. 84, NO. 14, doi:10.1029/2003EO140001, 2003

Investigating a 65-Ma-Old Smoking Gun: Deep Drilling of the Chicxulub Impact Structure

B. O. Dressler

Lunar and Planetary Institute, Houston, Texas, USA


V. L. Sharpton

University of Alaska, Geophysical Institute, Fairbanks, Alaska, USA


J. Morgan

Imperial College, T. H. Huxley School of Environmental, Earth Sciences, and Engineering, London, UK


R. Buffler

University of Texas at Austin, Institute of Geophysics, Texas, USA


D. Moran

Universidad Nacional Autonoma de Mexico, Instituto Geologia, Mexico City, Mexico


J. Smit

Purdue University, Earth Sciences, West Lafayette, Indiana, USA


D. Stöffler

Humboldt Universität, Institut fuer Mineralogie und Petrography, Berlin, Germany


J. Urrutia

Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, Mexico City, Mexico


Abstract

The Phanerozoic paleontological record is marked by several biological extinction events. One of them, at the Cretaceous/Tertiary (K/T) boundary, was responsible for the demise of about 5% of genera and 75% of species, including the dinosaurs. These drastic and abrupt changes in the development of life on Earth puzzled paleontologists in the past. Many a cause was put forward to account for them, amongst them climate changes, disease, or overspecialization. About 20 years ago, Alvarez et al. [1980] discovered a high iridium concentration in an Italian K/T boundary clay layer. They proposed that the iridium was derived from an extra-terrestrial impact 65 Ma ago and that the impact was the cause for the K/T boundary extinctions. The iridium layer was subsequently found at K/T boundary locations worldwide. Further evidence for a K/T impact came from the discovery of shocked quartz, nano-diamonds, glass spherules, and nickel-rich spinels in microkrystites in the iridium-rich layer. There was evidence for an impact event, but no crater.

Index Terms: 5420 Planetology: Solid Surface Planets: Impact phenomena (includes cratering).

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Citation: Dressler, B. O., V. L. Sharpton, J. Morgan, R. Buffler, D. Moran, J. Smit, D. Stöffler, and J. Urrutia (2003), Investigating a 65-Ma-Old Smoking Gun: Deep Drilling of the Chicxulub Impact Structure, Eos Trans. AGU, 84(14), doi:10.1029/2003EO140001.