A Scalar Audiomagnetotelluric Survey Across an Outcropping Dike

Abstract

—This work presents a modeling study of the shallow electric signature of an outcropping dike of the Guapiara Lineament in the Parana Basin, Brazil. The forward geoelectrical model was constructed on the basis of the response functions obtained with a scalar AMT data set along a profile perpendicular to the strike of the dike. The objective was to assess the shallow electrical signature of a typical dike in Parana Basin, which is beyond the spatial sampling of a typical long period tensor MT survey. The geoelectrical model presented in this paper identified the dike, a Permian sedimentary sequence and a quaternary alluvial deposit. The dike intruded through a normal fault, which was characterized by its vertical offset and the identification of the hanging and foot walls. The dike is strongly anisotropic with a resistivity value along the strike that is two orders of magnitude smaller than along the perpendicular direction. The hypothesis of an anisotropic dike is supported by an independent data set.