Comparison of laboratory and field electrical resistivity measurements of a gypsum rock for mining prospection applications

Abstract

Abstract Geophysical surveys are frequently applied in mining prospection to detect the presence and volume of ore bodies of different nature. Particularly, in gypsum ore bodies exploitation, electrical resistivity measurements are usually the most used methodology. However, it has been observed that different electrical resistivity values can be obtained depending on geometrical features and composition of gypsum. Indeed, electrical resistivity of gypsum rocks depends on several parameters, such as gypsum purity, nature of secondary minerals, porosity, saturation and interstitial fluid properties. Saturation and hydrogeological setting, in particular, were recognized as the most influencing parameters. Hydrogeological conditions of gypsum rock masses are also very relevant for exploitability, safety conditions and economic feasibility and should be accurately known during the prospection and planning phases of the quarries. In this work, a relationship between electrical resistivity and saturation degree of gypsum is proposed. The possibility to estimate gypsum porosity with the use of this relationship is also investigated. The reliability of laboratory measurements is finally verified in comparison with field and modelled resistivity data. The reported results underline the potentiality of the proposed approach to obtain a reliable characterization of the studied ore body.