VERTICAL ELECTRIC PROFILE AT CHOUTUPPAL (HYDERABAD) IN PENINSULAR INDIA

Natural electromagnetic (e.m.) field data form Choutuppal (Hyderabad) in the frequency range 2 × 10-1 - 1 × 10-4 Hz are processed and resistivities in the principal directions determined. A 1-D inversion of the resulting ρyx curve reveals the existence of three conductive layers: (1) depth to the [top = 16 km, thickness = 9 km, resistivity = 35 μ m; (2) depth to the top = 90 km, thickness = 15 km, resistivity = 15 μ m; and (3) depth to the top = 340 km, thickness = 10 km, resistivity = 3 μ m. Whereas the mid-crustal conductor has been visualized as a low-velocity layer corresponding to the Conrad discontinuity, the second conductor has been ascribed to the uplifted asthenosphere as a result of the thinning of the lithosphere and the third has been related to the global conductivity zone arising from olivine to spinel phase transition. © 1990.