Mapping of salt structures and related fault lineaments based on remote-sensing and gravimetric data: The case of the Monte Real salt wall (onshore west-central Portugal)

Abstract

The Monte Real (MR) salt wall (MR structure) is a salt structure located in the Monte Real–Pombal Subbasin (onshore west-central Portugal). The MR structure was emplaced during post–Triassic–Mesozoic extensional and Tertiary compressional tectonics and is now partially buried under Miocene to Pliocene–Pleistocene sediments. The region is dominated by NS 20, N45 10E, N30 10W, and N70 10W trending main tectonic systems. Remote-sensing data constrained by gravimetric data allowed the recognition of the two-dimensional surface geometry of this salt structure and its associated structural features. The use of remote-sensing images (optical and microwave data) allow mapping the MR structure based on the heat radiated from rocks and soils, changes in vegetation cover, and texture analysis of synthetic aperture radar imagery. In addition, remote-sensing data, combined with modeled topographic data, also allowed recognition of a lineament pattern consistent with the fracture pattern of the region, probably related to the implantation and deformation of this salt body. The crosscut behavior of the identified structural lineaments can justify the north-northwestern elongated arcuate shape of the MR structure and the corresponding gravimetric anomaly. This work shows that remote-sensing techniques are a powerful tool to study buried salt domes even in the absence of detailed geophysical data.