HR: 0800h
AN: S31A-06    [Abstracts]
TI: A magnetotelluric transect through the Sierra San Pedro Martir, northern Baja California, Mexico
AU: * Pamplona, U
EM: upamplon@cicese.mx
AF: CICESE, Km 107 Carretera Tijuana-Ensenada, Ensenada, BC 22860, Mexico
AU: Romo, J M
EM: jromo@cicese.mx
AF: CICESE, Km 107 Carretera Tijuana-Ensenada, Ensenada, BC 22860, Mexico
AB: Preliminary results of a magnetotelluric transect through the Sierra San Pedro Martir, in northern Baja California, Mexico, reveal a high conductivity anomaly possibly associated with a shear zone developed during a major accretion episode in Cretaceous time. Enhancement of electrical conductivity in the rocks of the upper crust highly depends on the presence of fluids and/or conductive minerals, like those produced by metamorphism. Hence, the assessment of subsurface conductive anomalies may contribute to understand the tectonic evolution of Baja California peninsula. We use series and parallel magnetotelluric invariant impedances and a 2-D inversion technique to obtain resistivity models of the crust. The search for the best resistivity model is based on a regularization scheme, where a balance between data misfit and model roughness is looked for. At this stage, we have only a 60 km-long transect across the Peninsular Ranges batholith, but in the close future it will be completed to include measurements toward the east, across the western end of the Gulf of California extensional province.
DE: 7218 Lithosphere (1236)
SC: Seismology [S]
MN: 2007 Joint Assembly