Prospecting of industrial minerals: a geophysical approach

This work deals with the evaluation of the electrical resistivity method for the identification and characterization of industrial minerals deposits.The ERT (Electrical Resistivity Tomography) technique is demonstratively applied to 4 different areas of the central and northern Sardinia.The research focused on clays, which generally have conductivity values greater than those of the host lithotypes. In this regard, a bentonite deposit close Ozieri (N-Sardinia) was investigated by 2D and 3D ERT surveys, and a preliminary study was conducted in the northern part of Nurra (NW-Sardinia) in order to discriminate Messinian clay deposits from the underlying bedrock.The ERT method was also tested on cineritic levels, which for their absorption properties are increasingly required as litter for pets. Potentially exploitable cineritic levels have been identified in two different sites of central Sardinia (Macomer and Zerfaliu), within the Oligo-Miocene calcalkaline volcanic sequence.In all the 4 case studies it is attempted: 1) to define the geometry of the deposits; 2) to estimate the reserves and locate the main faults useful to decipher the ore-forming processes; 3) to evaluate the reliability of the ERT method by cross-checking the results with boreholes data.The results indicate that ERT method may represent a relatively cheap and powerful tool to obtain high-resolution geological and stratigraphic information on clayey and cineritic bodies.