Imageamento unidimensional de dados magnetotelúricos sob a Bacia Sedimentar Tucano Central e o Bloco Serrinha, NE do Brasil

Abstract

The magnetotelluric (MT) method seeks to obtain the distribution of subsurface electrical conductivity by measuring the variation of surface electric and magnetic fields. The present work shows an interpretation of the tectonic structures of the continental crust in the southwest of the Borborema province and northeast of the São Francisco craton in northeastern Brazil. A region that has a great geodynamic complexity related to its genesis, and little information about its subsurface boundaries. What has made this area the object of study in order to elucidate the evolutionary processes that led to its genesis. For this study we used magnetotelluric data from the CNPq −573713/2008−1 project, funded by the Milêncio Institutes program, linked to the National Institute of Science and Technology in Tectonic Studies (INCT-ET), which would appear between the University of Brasilia and the group. Geomagnetism Institute. INPE made available data from14 stations that are arranged along alinear profile of approximately160km, which cuts perpendicularly the main tectonic units of this region (Tucano Central sedimentary basin and the Serrinha block). These data were processed by advanced techniques currently available for studies of electromagnetic induction within the earth. To obtain the1D geoelectric model, the free version Zond1DMT software was used. By analyzing the results of the pseudossessions it is possible to observe the presence of a conductor throughout the middle crust along the profile. The results show geoelectrically distinct regions, an upper crust under the Serrinha block west portion of the profile (which coincides with the basement of the São Francisco craton) and the central Tucano basin east portion (which coincides with the sedimentary package of the Tucano basin). . The dimensionality analysis shows that the eastern portion of the profile is very well defined with the predominance of 1D structures with periods ranging from 104 to 1s coinciding with the basin region studied. The results of the 1D inversion geoelectric section well diluted the Tucano Central basin region. It also shows an unusual conductive anomaly for meso-archean structures (Serrinha block), and an anomaly under the Tucano Central basin interpreted as a fractured zone in the upper crust. This seems to be a regional feature of this rift system and may be related to the mechanisms of its basin generation. These points show the importance of this work that brings geophysical subsidies that seek to contribute to a better evolutionary understanding of the region.