Estruturas rúpteis da zona de falha São Jerônimo-Curiúva e seu potencial como rotas de migração na porção leste da Bacia do Paraná

Abstract

The study area is located around the cities of São Jerônimo da Serra, Sapopema and Curiúva, in the northeast of Paraná State, southeastern Brazil. Patterns of magnetic and gravity anomalies were compared with a digital elevation model and field observations to identify zones of intense deformation that could act as migration pathways for petroleum along the eastern boundary of the Paraná Basin. In this region, Paleozoic sediments, Mesozoic intrusions and volcanic outcrops are structurally controlled by the intersection of mega-structures, such as the axis of Ponta Grossa arch and the São Jerônimo-Curiúva fault zone, with the Jacutinga fault zone. The dataset was divided into subsets according to the mapped stratigraphy, regional geology and data from an exploratory oil well. Faults and fractures were identified in outcrop and were associated with regional strike-slip and normal faults. The structural data were analyzed in rosette diagrams, Schmidt-Lambert plots, and structural modeling software. N70-80E and N20-30W were identified as the directions with the higher density of fractures. N40-50W trending diabase dikes were observed in the field and correlated with the positive magnetic anomalies and with lineaments identified on the digital elevation model. These dikes are locally related to normal faults formed under a regime of pure extension, with σ3 oriented in the N258/13 direction. The fault zones adjacent to diabase dikes commonly display damage zones up to 2-meter wide, with the formation of fault gouge and small fractures that would increase the permeability towards the fault zone. The fault zones favor the migration of oil that may occur during tectonic pulses that would result in displacement along the faults over the geologic time.