HR: 0830h
AN: GP41A-10    [Abstracts]
TI: Magnetic Properties in Volcanoclastic Deposits in the Valle de Santiago, Guanajuato, in Central Mexico.
AU: * Uribe-Cifuentes, R
EM: rosiuc@aol.com
AF: National University of Mexico, Instituto de Geofisica, UNAM D. Coyoacan, Mexico, DF 04510 Mexico
AU: Fucugauchi, J U
EM: juf@geofisica.unam.mx
AF: National University of Mexico, Instituto de Geofisica, UNAM D. Coyoacan, Mexico, DF 04510 Mexico
AB: Valle de Santiago is a volcanic province, part of the Michoacan-Guanajuato volcanic field. The area is characterized by volcanic maars. These structures show a very well defined NW-SE direction. In this study, three sequences are described and analysed in order to determinate their magnetic properties, specially, anisotropy of magnetic susceptibility (AMS), and determinate different types of signatures in relation to nature of deposits. The sequences of maars contain a high percentage of reworked material (approximately 65-75) from previous rocks. This arrangement is directly related with a high kinetic energy during the eruption. All the deposits are unwelded, and principally are fine grained pyroclastic deposits of hydromagmatic origin. Volcanic and magnetic data suggest an alternation of fall and turbulent transportation and traction deposition of particles. The preliminary results indicate the anisotropy of magnetic susceptibility (AMS) could be related with grain size, chemical composition, and type of deposit.
DE: 1518 Magnetic fabrics and anisotropy
DE: 1520 Magnetostratigraphy
DE: 1527 Paleomagnetism applied to geologic processes
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2005 Joint Assembly