Contribution of geophysical methods in mining exploration: Case study of El Haouaria-Oued Brache-Northern Tunisian Atlas

Abstract

The Northern Tunisian Atlas hosts numerous lead‑zinc ore deposits. While most of the shallow resources have been depleted, relatively deep structures remain underexplored and the use of geophysics is very limited. The El Haouaria-Oued Barche, located in Oued Zarga (northern Tunisia) represents one of these under-explored structures. This mine was in production from 1906 to 1940 before closing due to water ingressions in the underground galleries, which damaged the site infrastructure and posed safety risks. In this study, we use a range of geophysical techniques including gravity, Electrical Resistivity Imaging (ERI), and induced polarization data to understand the structure of El Haouaria-Oued Barche ore deposits and to explore potential subsurface targets for future drilling exploration programs. Geophysical lineament extraction represents one of the most useful techniques successfully successfully applied to mineral exploration. First, gravity data has been analyzed to map the contrasting gravity responses related to changes in density. The main identified lineaments coincide more or less with known faults/contacts and new directions have been identified. The main directions are NE-SW, NW-SE, E-W, and N-S. In a second step, IP was used to study disseminated pyrite associated with lead‑zinc mineralization. Gravity was used to map the structure and directly detect massive sulfide bodies within 200 m of the surface. Compared to Bouguer's anomaly, the obtained residual map brings to light some new features previously masked. The most distinctive features of the residual gravity are High-gravity anomalies positive. This suggests that the size of these deposits is very low. If the mineralization is not associated with pyrite or chalcopyrite, it is unlikely to be identified with IP. The horizontal gradient map has allowed a better delineation of the subsurface structural features of the area and can serve as a background document to guide future mineral exploration within this ore deposit.