A MT/GDS survey has been carried out around the NW plunging Torres Syncline in the southeastern border of the Paraná Basin, in Brazil. Induction arrows show a NW‐trending conductive anomaly nearly coincident with the hinge of the syncline and ocean effects varying as a function of the distance from the coast. 2‐D inversions of MT data along two profiles parallel to the coast and across this anomaly have distinguished electrical anomalies in the upper crust. The most prominent of these anomalies is an electrical conduit dipping to the NW from a depth of 500 m at the coast to 1000 m at a distance of about 100 km further inland. The conductor, located in the crystalline basement, can be possibly ascribed to residual metasomatic fluids concentrated along the hinge of the downfolded Torres Syncline, as a fossil record of the Early Cretaceous volcanic events that affected the Paraná Basin and underlying lithosphere.