Ore-controlling structures revealed by magnetic and resistivity anomalies in the Linares–La Carolina mining district (Spain)

Abstract

The effectiveness of magnetic and electromagnetic geophysical methods in delineating geological structures with mining implications was analysed in this study, specifically for structures that affect the possible extension of the lead-based metal phylonian deposits concealed by young sedimentary cover. This study focuses on the ancient mining district of Linares–La Carolina (south-eastern Spain), characterized by the presence of galena (PbS) deposits. In this sector, two of its main mining concessions (Arrayanes and San Miguel–El Mimbre) were selected, which lose continuity under the Plio–Quaternary basin cover of La Garza. The magnetic surveys reveal the presence of anomalies aligned in two directions, NW‒SE and SW‒NE. Calculated magnetic models indicate that these anomalies could be associated with faults. The continuity of the veins is disrupted or displaced when these anomalies are reached. Therefore, the study of these linear magnetic trends can help to locate these faults that control the continuity and displacement of the veins. Joint interpretation of new time-domain electromagnetic stations and electrical resistivity tomography profiles previously obtained reveal linear features that align with the faults interpreted from the magnetic results. This consistency between methods allowed us to corroborate the presence of these structures. The synergistic application of magnetic techniques alongside electrical or electromagnetic methods proves effective in identifying faults in the Arrayanes and San Miguel–El Mimbre mining concessions. The identified faults are significant for prospecting for mineral deposits as they are spatially associated with both vein disappearances and lateral changes in facies and thickness in the Quaternary fill of the La Garza sedimentary basin. This is evidence that the geophysically mapped faults have meaningful control on ore vein distribution.