Historic Underground Silver Mine Workings Detection Using 2D Electrical Resistivity Imaging (Durango, Mexico)

Abstract

This paper presents an underground silver mining operation outside Gomez Palacio, Durango, Mexico, terminated around the 1930s, of which previous knowledge of its operations was poor. Durango’s current silver exploration campaigns are likely to overlook historic silver mining sites due to interest in specific prospect regions. A two-dimensional (2D) Electrical Resistivity Imaging (ERI) survey coupled with reconnaissance of the area was performed at this historic silver mining site. The exploration campaign aimed to find the abandoned mineshaft, map its subsurface extent, and explore the occurrence of mineralization zones (silver ore). The ERI survey comprised five profiles measured with the extended dipole-dipole array with a consistent electrode spacing of 5 m. The smooth, robust, and damped least-squares inversion methods were used to invert the 2D data. Our field observations and ERI survey results collectively reveal the following findings: (a) reconnaissance reveals mining infrastructure consistent with historical mining activity; the infrastructure includes a complex of habitational rooms, an ore-processing pit near a concrete slab next to a dirt road, and two limestone-wall structures interpreted as the entrance of abandoned backfilled mineshafts named Mesquite and Lechuguilla; (b) high-resistivity anomalies suggest vestiges of shallow, underground mine workings including backfilled mineshafts that connect a mine gallery complex, and (c) various low-resistivity anomalies, juxtaposed against mine galleries, suggestive of unmined shallow vein-type and manto-type mineralization of hydrothermal origin. The imaging depth is estimated at ~65 m. Underground silver mining moved southwards and was limited to ~40 m depth.

Application of Electrical Resistivity Tomography in Geotechnical and Geoenvironmental Engineering Aspect

“…It is a nondestructive test, and the purpose of electrical surveys is to determine the subsurface resistivity distribution by making measurements on the ground surface and also characterize subsurface properties, i.e., structure, water content, or fluid composition [2]. This method is widely used in hydrogeological, environmental, and geotechnical research as it can potentially reveal the subsurface image [3][4][5][6][7][8][9][10]. This technique is used for the investigation of morphotectonic [11], weathering studies [12], landform evolution in mountain areas [13], permafrost detection [14], and exploration of underground karst structures [15].…”

“…That is why the ERT technique is now often used in landfills to inspect the moisture variation in the landfilled waste and the rate of waste degradation to have controlled leachate generation [25]. Apart from this, ERT technology is now vastly being used in geotechnical investigation [4][5][6][7][8][9][10]21,26]. To determine the unknown foundation depth, slope failure investigation, crack detection, the existence of sinkholes, foundation failure, moisture variation in pavement base materials, soil movement, etc., are broadly examined by the ERT method.…”

Application of Electrical Resistivity Imaging (ERI) to analyse geological structure in Paloh, Gua Musang, Kelantan

“…Specifically, the spatial distribution of the low-frequency resistive and capacitive characteristics of underground earth materials was imaged using electrical resistivity and IP imaging. [2] [3]. A geological assessment is implemented in Paloh area to analyse the subsurface geological structure as the area is prone to landslides.…”

Editorial for the Special Issue “Electromagnetic Exploration: Theory, Methods and Applications”

“…It was demonstrated that the water-bearing structures can be observed by a magnetic field (with a perpendicular, horizontal electric dipole (HED) source) rather than an electric field (with a parallel HED source). Through the application of the low-frequency end of EM waves, Hinojosa et al [14] provided an example of a 2D electrical resistivity imaging (ERI) survey at a historic silver mining site in Durango, Mexico. They successfully detected the abandoned and undocumented historic silver mining infrastructure, including mine workings represented by high-resistivity anomalies and unmined mineralization zones with low-resistivity anomalies.…”