3 research outputs found
Outcropping analogs and multiscale fracture patterns in the JandaÃra formation
Outcropping analogs can provide key information on the 3D organization of fracture networks affecting carbonate reservoirs. Such information, however, needs to be integrated in a consistent work flow which includes i) 3D geometric model of the reservoir architecture, ii) mechanic modeling to determine areas of fracturing, iii) characterization of fracture networks, iv) determination of fracture-related permeability in small representative volumes and v) fluid flow simulations. Fracture networks have been recently analysed from km-scale pavements of the Jandaira Formation in NE Brazil. Combining images from a drone with outcrop analysis and thin section we present the first multiscale characterization of the fracture field affecting the shallow water carbonates.Geoscience & EngineeringCivil Engineering and Geoscience
Dissolution along fracture systems in Turonian-Campanian carbonates in Brazil
Geoscience and EngineeringCivil Engineering and Geoscience
Hydrothermal activity along a strike-slip fault zone and host units in the São Francisco Craton, Brazil – Implications for fluid flow in sedimentary basins
This study combines multiscale analyses of geological, fault, fracture, and stable isotope data to investigate strike-slip deformation and channeling of hydrothermal fluids along the Cafarnaum fault and calcite veins at different distances from the fault, which is a structure in the São Francisco Craton, northeastern Brazil. Meteoric fluids with δD values near −45‰ and δ18O values near −6.5‰ and temperatures at 40–70 °C precipitated as calcite veins in the host carbonate units. The Cafarnaum fault, a N-S-striking vertical, ~170 km long fault zone, juxtaposes Neoproterozoic carbonate rocks in the western block and Mesoproterozoic siliciclastic rocks in the eastern block. A zone of restraining bends occurs at the central part of the fault, whereas termination zones of horsetail geometry occur at both ends of the Cafarnaum fault. These zones are marked by NW-SE-striking extensional faults that are oblique to the main N-S-striking fault zone, where hydrothermal deposits occur. The zone of influence of the Cafarnaum fault is ~ 20 km wide around the main fault. The fault formed during the Brasiliano orogeny (740–560 Ma) after Neoproterozoic carbonate platform deposition. In contrast with the host units, fluids along the fault zone originated in deeper levels of the crust and show much lower δ18O values, indicating higher crystallization temperatures. These fluids caused brecciation in the Neoproterozoic carbonate host rocks, whereas a subsequent decrease in fluid pressure and cooling near the surface resulted in the precipitation of a hydrothermal paragenesis in veins, also affecting the host rock.Accepted Author ManuscriptApplied Geolog