UTIG RESEARCH PROJECTS ARCHIVE

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Abstract
Award is for a multichannel seismic survey across the offshore portions of the Chicxulub impact crater. The multichannel seismic survey will be added on to a funded British tomographic survey that will be conducted in the summer of 2003 aboard the R/V Maurice Ewing. The multichannel seismic survey will map features that cannot be constrained by the tomographic study, including the geometry of the peak ring, and the possible thrust boundary beneath the peak ring. The modeling effort, together with the multichannel seismic profiles will determine the approach direction of the impactor and constrain the angle of impact to with 10 degrees. The multichannel seismic profiles together with the tomographic data will complete the required site survey over two proposed IODP sites.

Introduction
Sixty-five million years ago a ~10 km diameter meteor crashed into the Yucatan Peninsula of Mexico leaving behind the 195 km wide Chicxulub crater (Figure 1) which is one of only three known impact craters on Earth with diameters larger than 150 km. Seventy percent of the species on the Earth including the dinosaurs became extinct at the Cretaceous-Tertiary (K-T) boundary, which appears to have been caused, at least in part, by this impact. In addition to being the cause of the K-T extinction event, Chicxulub is the only one of the three large craters on Earth that is well preserved due to a cover of ~1 km of Tertiary (post-impact) limestones. The Chicxulub crater is uniquely suited for a seismic investigation into the way large diameter impacts deform the Earth and what the specific environmental effects of the Chicxulub impact were at the KT boundary.

The goals of our combined reflection-refraction seismic experiment are: 1) We seek to determine the direction of approach and angle of the Chicxulub impact as modeling has shown that a 15-20 time greater amount of airborne particles are produced by low-angle impacts; 2) We will map the deformation (faults and broken rock) recorded in the upper crust near the crater center that may explain the way the surface of the Earth is damaged by large meteor or comet impacts; 3) By imaging the key features in the northwest portion of the crater we can further understand the Chicxulub impact structure and prepare for possible future sampling to examine the melted and shattered rocks deep within the crater; 4) We intend to model the 3-D collapse of the crater to examine both the deformation and the environmental effects of the impact to better understand how such an impact can cause worldwide mass extinctions.

Check out the 1996 Chicxulub Project!