HR: 08:00h
AN: S41A-05    [Abstracts]
TI: Chicxulub Peak Ring Characteristics from 2D Reflection Seismic Survey
AU: * Mendoza-Cervantes, K
EM: keren@geofisica.unam.mx
AF: Universidad Nacional Autónoma de México, Universidad Nacional Autónoma de México, Circuito Institutos S/N, Ciudad Universitaria, Mexico City, 052 04510, Mexico
AU: Fucugauchi, J U
EM: juf@geofisica.unam.mx
AF: Universidad Nacional Autónoma de México, Universidad Nacional Autónoma de México, Circuito Institutos S/N, Ciudad Universitaria, Mexico City, 052 04510, Mexico
AU: Gulick, S
EM: sean@ig.utexas.edu
AF: University of Texas at Austin, Institute for Geophysics Jackson School of Geosciences University of Texas at Austin J.J. Pickle Research Campus (ROC) 10100 Burnet Rd. (R2200) Austin, Texas, Austin, Texas, 512 78758-4445, United States
AB: Since 1980's research interest over Chicxulub crater located SE Gulf of Mexico, has grown not only because its relationship with the K-P(Cretaseous -Paleogene) extinction but because of its size (diameter ~ 200 km) and grade of preservation. Based on results from several surveys using different geophysical methods, Chicxulub has been classified as a multiring crater. A topographic high rising from crater floor was first recognized as the Chicxulub peak ring on four 1996 reflection seismic profiles but the low density of this data set made impossible to describe on detail this structure. Recently, during 2005 we carried out a marine survey acquiring 29 profiles. A grid located over the central marine portion of the crater was conformed by eleven profiles 80 km long oriented WSW-ENE and ten 25 km long NW-SE. Data was recorded on 480 channels spaced 12.5 cm on a 6 km streamer and air guns were shot every 50 m allowing us to image the earth up to 14 s TWTT. This new data set along with the 1996 profiles allow us to build up the first 3D image of Chicxulub peak ring as well as to analyze some important features of this ring. Results show that the peak ring lays down closer to the surface and the crater rim on its NW portion where it rises more abruptly from the crater floor reaching up to 430 m. Based on the information of the radial lines this characteristics change in clockwise direction being opposite on the NE. The relationship between the peak ring and other Chicxulub structures,such as the slump blocks and the dipping reflector, change as well in the same direction indicating that the peak ring is displaced to the NW. These asymmetries could be related to the process of formation of the peak ring as a result of: a)an asymmetric collapse of the central uplift which has been proved not to be related to impact direction, b) displacement of the central uplift towards the transient cavity rim or c)heterogeneities on impact surface predating the impact.
UR: http:www.ig.utexas.edu/people/staff/sean/
DE: 0900 EXPLORATION GEOPHYSICS
SC: Seismology [S]
MN: 2007 Joint Assembly