On mapping multiple electrical discontinuities associated with deep seated anisotropic oblique zones using magnetotelluric frequency sounding

Abstract

Connection of anisotropy with main tectonic fracture zones is strongly supported by induction studies in geodynamically active areas. Hence, knowledge about the anisotropic effects in the subcrustal lithosphere, along with the relative contributions of electrical discontinuities, forms one of the basic requirements of the geodynamical studies. In this paper, an attempt is made to model a complex crustal situation, with an intermediate conducting layer sandwiched between a dipping anisotropic lower half space and poorly conducting upper formations. Analysis of numerical results reveals that: 1. (1)|multifrequency variation technique has the capability to resolve more than one electrical subsurface discontinuity situated at different depths; and 2. (2)|plane wave magnetotelluric impedance has a better response for higher dip angles and increasing anisotropic coefficients. Study may find relevance in delineating an intermediate conducting layer (usually associated with zones of increased geothermal activity, intensive magnetic anomalies and volcanogenic formations) covering deep seated anisotropic oblique zone.