Inversion of TEM data and analysis of the 2D induced magnetic field applied to the aquifers characterization in the Parana basin, Brazil

Results of a TEM profile by using the fixed-loop array and an analysis of the induced magnetic field are presented in this work performed in the northwest region of Sao Paulo State, Brazil, Parana Basin. The objectives of this research were to map the sedimentary and crystalline aquifers in the area and analyzing the behavior of the magnetic field by observation of magnetic profiles. TEM measurements'in the three spatial components were taken to create magnetic profiles of the induced (secondary) magnetic field. The TEM data were acquired using a fixed transmitter loop of 200 m x 200 m and a 3D coil receiver moving along a profile line of 1000 m. Magnetic profiles of dB(2), dB(x) and dB(y) components showed symmetrical spatial behavior related with loop geometry. z-component showed a behavior probably related to superparamagnetic effect (SPM). dBx data was used to perform individual 1D inversion for each position and to generate an interpolated pseudo-2D geoelectric profile. The results showed two low resistivity zones: the first shallow, between 10 m and 70 m deep, probably related to the Adamantina Formation (sedimentary aquifer). The second between 200 m and 300 m depth, probably related to a fractured zone filled with water or clay inside the basalt layer of the Serra Geral Formation (crystalline aquifer). These results agree with the well logs information available in the studied region. (C) 2017 Elsevier B.V. All rights reserved. (AU)