Data from six airborne magnetic surveys were compiled and analyzed to develop a structural interpretation for the Transbrasiliano Lineament in northern Paraná Basin, Brazil. Magnetic lineaments, interpreted to reflect geologic contacts and structures at different depths, were illuminated using the matched-filter technique applied to aeromagnetic anomalies. Field-based structural measurements generally support our magnetic analysis. We estimated three primary magnetic zones: (i) a zone of deep magnetic sources at 20 km depth, (ii) an intermediate basement zone at 6 km depth, and (iii) a shallow zone of near-surface geological features at 1.5 km depth. The deepest zone exhibits three major NE trending crustal discontinuities related to the Transbrasiliano Lineament, dividing the region into four geotectonic blocks. Anomalies associated with the intermediate zone indicate directional divergence of subsidiary structures away from the main Transbrasiliano Fault, which strikes N30°E. The shallow magnetic zone includes near-surface post-Brasiliano orogenic granites. Our analysis identified NE trending sigmoidal lineaments around these intrusions, indicating intense zones of deformation associated with probable shear structures. At the shallow depth zone, magnetic anomalies caused by Cretaceous alkaline intrusive bodies and basalts of the Serra Geral Formation are enhanced by the matched-filter method. These igneous bodies are related to extensional NW striking lineaments and seismicity aligned along these lineaments suggests that they currently are reactivated. Prior to flexural subsidence of the Paraná Basin, reactivation processes along transcurrent elements of the Transbrasiliano Lineament promoted extensional processes and formed initial Paraná Basin depocenters. Cretaceous and more recent sedimentation also correlate with reactivations of NE striking structures.

The first direct indication of hydrocarbon occurrence in Remanso do Fogo area (Minas Gerais State, Brazil) was the existence of microseepages. However, Quaternary sedimentary cover in the area made the identification of new occurrences and associated controlling structures quite difficult. This study investigated the spatial distribution of hydrocarbon related gases in shallower to intrasedimentary depths in Remanso do Fogo area, using airborne gamma-ray spectrometry and magnetic data. The geophysical data were processed using techniques designed to suppress the influence of regional geological signatures. Known and possible new occurrences of microseepages were detected by mapping low residual potassium values and high uranium residual values in relation to potassium, termed as DRAD values, which resulted from the subtraction of potassium from uranium residual values, using a Thorium (Th)-normalizing approach. The validation of these occurrences was done based on existing gas geochemistry data in the soil. For the magnetic data, the amplitude of the analytic signal, combined with the total horizontal gradient of the subtraction between the 1200- and 400-meter upward continuations, enhanced the northwest–southeast and east–west magnetic lineaments, which are partially related to the microseepages and the drainage of the area. The distinction of near-surface and deep signatures also allowed the general identification of intrasedimentary and basement structures, which are potentially controlling the occurrences of seepages in the area.

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