HR: 1340h
AN: GP13A-0037    [Abstracts]
TI: Effects of Heating on Magnetic Susceptibility Anisotropy of Impact Breccias From the Chicxulub Crater, Mexico
AU: * Urrutia-Fucugauchi, J
EM: juf@geofisica.unam.mx
AF: Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, UNAM, Coyoacan, Mexico City, DF 04510 Mexico
AU: Delgadillo, M
EM: secpal@geofisica.unam.mx
AF: Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, UNAM, Coyoacan, Mexico City, DF 04510 Mexico
AU: Velasco, M
EM: secpal@geofisica.unam.mx
AF: Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, UNAM, Coyoacan, Mexico City, DF 04510 Mexico
AU: Soler-Arechalde, A
EM: anesoler@geofisica.unam.mx
AF: Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, UNAM, Coyoacan, Mexico City, DF 04510 Mexico
AB: Interest on investigating effects of heating on the magnetic susceptibility anisotropy (AMS) has increased and studies on a wider range of lithologies are being analyzed. Initial studies on sedimentary rocks documented enhancement of the AMS fabrics with laboratory heating. Here we concentrate on the anisotropy of magnetic susceptibility of impact breccias measured at low magnetic fields; in particular, on the effects of laboratory heating on the AMS and potential use in enhancing the directional magnetic fabrics. We report results for the breccia sequence of the Chicxulub crater, which is a large complex multi-ring structure formed in the Yucatan carbonate platform at the Cretaceous/Tertiary boundary. Samples are recovered from cores recovered in the Yaxcopoil-1 borehole (between about 800 to 900 m depth), which was drilled in the southern inner sector of the crater. Chicxulub breccias present carbonate-rich and melt-rich matrix, with clasts from a large range of lithologies from the Yucatan basement units and melt material. In general, study of the anisotropic properties of magnetic susceptibility and remanent magnetizations of impact lithologies has received relatively little attention in paleomagnetic research. These studies have implications for the cratering processes, generation and deposition of breccias, and hydrothermal metamorphism. Mineralogical changes resulting from heating samples have been recognized, but no data on impact lithologies including breccias and melt rocks have been reported. The use of temperature induced effects to investigate composite magnetic fabrics in heterogeneous materials such as the impact breccias is discussed.
DE: 1518 Magnetic fabrics and anisotropy
DE: 1519 Magnetic mineralogy and petrology
DE: 1527 Paleomagnetism applied to geologic processes
DE: 1540 Rock and mineral magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: Fall Meeting 2005