Processamento e modelagem de dados magnetotelúricos na região da Bacia do Tucano: Nordeste do Brasil

Abstract

In this work will be used magnetotelluric method (MT), which is a passive electromagnetic geophysical method, commonly used to obtain information on the distribution of the electrical conductivity of the earth's subsurface. The study area, which was applied the method is the basin of Tucano, one of the constituent basins system rift Recôncavo-Tucano-Jatoba, which would have developed during the break in the Mesozoic of South America and Africa, but whose reconstruction plate movement during the seafloor expansion story remains controversial. Surveys with the MT method were developed in order to determine geoelectric models for the study area, using for such data already available, granted by the National Institute for Space Research (INPE), which were collected in the form of profile. The data were processed and modeled with advanced techniques currently available to the community of electromagnetic induction studies within the Earth. The proposed methodology consists of the relevant literature study, data processing and modeling to obtain the electrical conductivity variation within the Earth under the profile measurements. To carry out the work has up to 24 MT soundings, which were processed to obtain various parameters used in creating the pseudo-sections. At this stage, were used computer programs in the public domain for academic use (described in Santos-Matos, 2012). The MT data from this study were processed using the robust code of Gary Egbert (Egbert, 1997). Two Egbert code subroutines are DNFF and TRANMT. The DNFF is used for the spectral analysis, obtaining the Fourier coefficients of the recorded time series. Then applies to TRANMT subroutine to estimate the impedance tensor elements from the Fourier coefficients previously generated. For the qualitative analysis of the functions of transfer MT were built pseudosections, obtained from the interpolation of the phases in the two orthogonal directions measures (XY and YX).