A Multidisciplinary Geophysical Approach to Characterize a Fracture Zone: The Southern Limit of the Mining District of Linares-La Carolina, Spain

Abstract

In many cases, the lateral extension of economically valuable mineral deposits is linked to fractures. Knowing the characteristics of these tectonic structures is crucial for determining the continuity of mineralization in the subsoil and, consequently, for planning their exploitation. To address this challenge, a multidisciplinary study was carried out using various geophysical techniques and direct field observations to analyze the effectiveness of each technique in the investigation of fractures. For this purpose, the mining district of Linares-La Carolina in southeastern Spain, known for hosting Philonian deposits of galena (PbS), was chosen. At the southern boundary of this mining district, the seams stopped being exploited when they lost their continuity due to the presence of a regional normal fault. This fault zone was responsible for hiding the seams under a thick sedimentary cover. Detailed geological mapping allowed us to deduce the presence of two fracture systems. The geophysical techniques of electrical resistivity tomography and the time domain electromagnetic method were used, allowing us to identify the positions and the vertical displacement of these faults. Furthermore, using magnetometry, the presence of a third system of fractures was deduced. The results showed that this multidisciplinary analysis provides information of interest concerning the complex structure that configures the limits of this mining district.