Borehole Resistivity And Electromagnetic Methods Applied to Mineral Exploration

Electrical methods using buried transmitters or receivers have become increasingly important exploration tools as exploration for deep mineral deposits has increased. A variety of resistivity methods have been developed and tested for borehole applications to mineral exploration, from simple mise-a-la-masse hole-to-surface arrays to more complicated hole-to-hole arrays. Time and frequency domain EM systems are currently being used principally for detecting the presence of massive conductors in resistive host rocks. Successful tests of hole-to-hole resistivity measurements for detecting old mine workings in a coal seam and hole-to-surface resistivity methods for determining the continuity of a mineralized zone are discussed in this paper. An example is shown of a surface-to-hole EM system that was used in an ore district near Sudbury, Canada to detect the presence of massive sulfide mineralization that was previously missed by exploratory drilling.