Magnetic vector inversion of selected anomalies underneath the sediments of Araripe basin, NE Brazil

Abstract

Contents of this paper were reviewed by the Technical Committee of the 17 th International Congress of the Brazilian Geophysical Society and do not necessarily represent any position of the SBGf, its officers or members. Electronic reproduction or storage of any part of this paper for commercial purposes without the written consent of the Brazilian Geophysical Society is prohibited. ____________________________________________________________________ This paper presents a new study of six selected magnetic anomalies underneath and around the Araripe sedimentary basin (NE Brazil) as a complementary tool for improving structural interpretation of the poorly-solved Araripe Basin, northeast Brazil. The basement is little known as the available seismic lines do not cross throughout the basin area as they were carried out only where there are roads. For this reason, airborne magnetic data are important for the general study of the basin. The data used were a compilation of three airborne survey datasets made available by the geological service of Brazil -CPRM. A magnetic vector inversion was performed for each individual anomaly and the results were displayed in a 3D environment for visualization and analysis of the resulting vectors. The results of the inversion yielded varied responses that led to the conclusion that three of the anomalies presented similarities that allowed us to infer that they were related to the same event, while the others presented different characteristics. We concluded that five of the six could be caused by igneous intrusions while the sixth is more complex and appears to have two sources: a fragment of a more magnetic rock of the basement and a younger intrusive body. The depths of the most magnetic groups of vectors of the anomalies' sources are compatible with the current knowledge about the depth of the basement underneath the sedimentary basin.