HR: 0800h
AN: T41A-0356    [Abstracts]
TI: An Estimation of the Electrical Resistivity of the Crust in Northern Baja California, Mexico, Based on Magnetotelluric Data
AU: * Pamplona, U
EM: upamplon@cicese.mx
AF: Centro de Investigacion Cientifica y Educacion Superior de Ensenada, B.C., km 107 carretera Tijuana-Ensenada, Ensenada, 22860, Mexico
AU: Romo, J M
EM: jromo@cicese.mx
AF: Centro de Investigacion Cientifica y Educacion Superior de Ensenada, B.C., km 107 carretera Tijuana-Ensenada, Ensenada, 22860, Mexico
AB: In this work we show an electrical resistivity model of the crust, obtained from a magnetotelluric transect through Sierra San Pedro Martir (SPM), in the northern Baja California, Mexico. The profile has a length of ~110 km and consists of 26 magnetotelluric (MT) sites located across the main tectonic structures occurring in Baja California crust. We used a set of magnetotelluric invariant impedances and a regularized inversion technique to estimate a 2-D resistivity model of the crust. The resulting resistivity model reveals a high conductivity anomaly dipping towards the east, possibly associated with a shear zone developed during a major accretion episode in Cretaceous time. In addition, the model provides information about the vertical extension of several plutonic bodies mapped in the surface. On the other hand, it is observed an increase in the conductivity at a depth of about 20 km, which could be associated to a weakness zone inferred by existent rheological models. Enhancement of electrical conductivity in the rocks of the upper crust highly depends on the presence of fluids and/or conductive minerals. Hence, the assessment of subsurface conductive anomalies may contribute to understand the tectonic evolution of Baja California peninsula.
DE: 0905 Continental structures (8109, 8110)
DE: 8109 Continental tectonics: extensional (0905)
DE: 8110 Continental tectonics: general (0905)
DE: 8159 Rheology: crust and lithosphere (8031)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting