HR: 09:45h
AN: P11A-05    [Abstracts]
TI: Seismically Imaged Architecture of the Chicxulub Impact Crater: Preliminary Results From the Last Cruise of the R/V Maurice Ewing
AU: * Gulick, S S
EM: sean@ig.utexas.edu
AF: Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, 4412 Spicewood Springs Rd., #600, Austin, TX 78759 United States
AU: Barton, P J
EM: barton@esc.cam.ac.uk
AF: Bullard Laboratories, University of Cambridge, Madingly Road, Cambridge, CB3 0EZ United Kingdom
AU: Christeson, G
EM: gail@ig.utexas.edu
AF: Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, 4412 Spicewood Springs Rd., #600, Austin, TX 78759 United States
AU: Morgan, J V
EM: j.morgan@imperial.ac.uk
AF: Dept. of Earth Science and Engineering, South Kensington Campus Imperial College, London, SW7 2AZ United Kingdom
AU: Warner, M R
EM: m.warner@imperial.ac.uk
AF: Dept. of Earth Science and Engineering, South Kensington Campus Imperial College, London, SW7 2AZ United Kingdom
AU: Urrutia-Fucugauchi, J
EM: juf@tonatiuh.igeofcu.unam.mx
AF: Dept. of Planetary Sciences & Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721 United States
AU: Melosh, H J
EM: jmelosh@lpl.arizona.edu
AF: Instituto de Geofisica, Universidad Autonoma de Mexico, Ciudad Universitaria Delegacion, Coyoacan, Mexico City, CP 04510 Mexico
AU: Rebolledo-Vieyra, M
EM: silvana@cicy.mx
AF: Coordinator del C.E.A., Calle 21 Nte., Lote 39, Manzana 26 S.M., 64 Cancun, QR 77524 Mexico
AU: McDonald, M
EM: matt@ig.utexas.edu
AF: Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, 4412 Spicewood Springs Rd., #600, Austin, TX 78759 United States
AU: Vermeesch, P M
EM: peggy.vermeesch@imperial.ac.uk
AF: Dept. of Earth Science and Engineering, South Kensington Campus Imperial College, London, SW7 2AZ United Kingdom
AU: Surendra, A T
EM: surendra@esc.cam.ac.uk
AF: Bullard Laboratories, University of Cambridge, Madingly Road, Cambridge, CB3 0EZ United Kingdom
AU: Goldin, T
EM: tgoldin@lpl.arizona.edu
AF: Dept. of Planetary Sciences & Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721 United States
AU: Mendoza, K
AF: Dept. of Planetary Sciences & Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721 United States
AU: Sears, T J
AF: Bullard Laboratories, University of Cambridge, Madingly Road, Cambridge, CB3 0EZ United Kingdom
AB: A new suite of multi-channel seismic reflection lines image key structural elements of the 195 km wide Chicxulub Impact Crater, the best preserved, large impact crater on Earth. The seismic transects, acquired using the R/V Maurice Ewing in January and February 2005, include regional radial lines (dip-oriented), a regional constant-radius profile (strike-oriented), and a dense grid of lines spaced 2 km by 5 km apart near the center of the crater. The radial lines image, from the exterior to interior, the crater rings, crater rim, slump blocks, and peak ring providing an enhanced look at the 3-D architecture of Chicxulub. The constant-radius profile, together with the radial lines, was designed to study any radial variations in deformation, or possibly ejecta, which may lend insight into impact angle and direction. The grid of lines near the crater center examine the structural relationships between the slump blocks, peak ring, and central uplift which according to impact modeling all formed within minutes of the Cretaceous-Tertiary impact. The regional lines, both radial and the constant radius profile, largely confirm the observations of the regional seismic lines collected in 1996. Both datasets show the existence of at least one ring outside of the crater rim and an elevated crater rim with as much as 500 m of offset between the top of the crater rim and the KT boundary within the crater that was subsequently buried by ~1 km of Tertiary sediments. Our preliminary interpretations from the seismic grid near the crater center yield a general architecture of the central crater that includes a 10-15 km wide, doughnut-shaped peak ring that lies ~25 km from the crater center. Underlying the peak ring are sediments with inconsistent reflectivity (possibly breccia), underlain by inward slumped blocks of varying widths, and underlain by ~10 km thick package of reflective lower crust ending with the Moho. The slump blocks, where imaged, underlie the peak ring suggesting slumping occurs early in the cratering process. The lower reflective crust also dips inward on occasion suggesting a possible structural interaction between the non-excavated crustal rocks and the central uplift.
DE: 5420 Impact phenomena (includes cratering)
SC: Planetary Sciences [P]
MN: 2005 Joint Assembly