HR: 0830h
AN: P21A-04    [Abstracts]
TI: 3-D Tomographic Imaging of the Chicxulub Impact Crater: Preliminary Results From EW&35;0501
AU: * Surendra, A T
EM: surendra@esc.cam.ac.uk
AF: Bullard Laboratories, University of Cambridge Madingly Road, Cambridge, CB3 0EZ United Kingdom
AU: Barton, P J
AF: Bullard Laboratories, University of Cambridge Madingly Road, Cambridge, CB3 0EZ United Kingdom
AU: Vermeesch, P M
AF: Dept. of Earth Science and Engineering, South Kensington Campus, Imperial College, London, SW7 2AZ United Kingdom
AU: Morgan, J V
AF: Dept. of Earth Science and Engineering, South Kensington Campus, Imperial College, London, SW7 2AZ United Kingdom
AU: Warner, M R
AF: Dept. of Earth Science and Engineering, South Kensington Campus, Imperial College, London, SW7 2AZ United Kingdom
AU: Gulick, S P
AF: Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, 4412 Spicewood Springs Rd., Bldg. 600, Austin, TX 78759 United States
AU: Christeson, G L
AF: Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, 4412 Spicewood Springs Rd., Bldg. 600, Austin, TX 78759 United States
AU: Urrutia-Fucugauchi, J
AF: Instituto de Geofisica, Universidad Autonoma de Mexico, Ciudad Universitaria Delegacion, Coyoacan, Mexico City, CP 04510 Mexico
AU: Rebolledo-Vieyra, M
AF: Coordinador del C.E.A., Calle 21 Nte., Lote 39, Manzana 26, S.M., Cancun, QR 77524 Mexico
AU: Melosh, H J
AF: Dept. of Planetary Sciences and Lunar and Planetary Laboratory, University of Arizona 1629 E. University Blvd., Tucson, AZ 85721 United States
AU: McDonald, M A
AF: Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, 4412 Spicewood Springs Rd., Bldg. 600, Austin, TX 78759 United States
AU: Goldin, T
AF: Dept. of Planetary Sciences and Lunar and Planetary Laboratory, University of Arizona 1629 E. University Blvd., Tucson, AZ 85721 United States
AU: Mendoza, K
AF: Instituto de Geofisica, Universidad Autonoma de Mexico, Ciudad Universitaria Delegacion, Coyoacan, Mexico City, CP 04510 Mexico
AB: The Chicxulub impact structure provides a unique opportunity to investigate the sub-surface morphology of large craters on Earth and other planets. The structure of the crater interior is still poorly known and there is much uncertainty over the sequence of events by which these large craters form and the magnitude of the subsequent catastrophic environmental effects. In early 2005, a reflection-refraction survey aboard the R/V Maurice Ewing imaged the deep structure of the Chicxulub impact. We present wide-angle data collected by a 3-D grid of 50 ocean bottom seismometers (OBSs), 86 three-component land stations and a 6 km long hydrophone streamer. The OBS grid, designed to image the peak ring and underlying structure of the northwestern quadrant of the crater, recorded shots from several seismic profiles in various orientations. Many of these profiles extended past the crater rim imaging to the base of the crust. Travel-time picks from this dataset, combined with existing 1996 data, will be inverted using the JIVE3-D tomographic inversion program to create a fully 3-D velocity model of the crater interior. The interpretation of the velocity model will focus on the morphology of the peak ring and the central uplift, and the distribution of breccia and suevite (an impact related breccia/melt) in the centre of the crater. We will calculate the Poisson's ratio for different areas of the crater using both the P-wave velocity model and S-wave arrivals, including those from the 1996 land station data. Comparisons of these values with measurements on the Yaxcopoil-1 core taken from within the crater provide ground-truth for our tomographic model. The contrast in Poisson's ratio between areas of suevite and the surrounding rock further constrain the distribution of breccia and suevite.
DE: 5420 Impact phenomena (includes cratering)
SC: Planetary Sciences [P]
MN: 2005 Joint Assembly