Volume 22 Number 4
  • E-ISSN: 1365-2478



Methods and typical case histories of EM and IP surveys are compared in order to check their compatibility for the investigation of large areas for base metal sulphides. It is demonstrated that the fast, low cost EM may miss sulphide concentrations which cause no reduction of apparent resistivity, or which act like horizontal slabs, where EM anomalies occur marginally. In such cases only IP can recognize the whole extent of the mineralization. The misleading role of graphite exists for both methods.

The conclusion is that EM remains the only economical method to survey whole ore districts, but that the shortcomings should always be taken into account in the interpretation. They can be overcome by employing geological, geochemical or other geophysical indicators in selecting promising targets for follow‐up IP. Even if less than 20% of the area is covered by the expensive IP, there is a fair chance that all sulphide bearing rocks will be found. Therefore, the question is not whether to apply EM IP methods, but how to combine them best.


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  1. Coggon, J. H., 1973, A comparison of IP electrode arrays: Geophysics38, 737–761.
    [Google Scholar]
  2. Fraser, D. C., 1969, Contouring of VLF-EM data: Geophysics34, 958–967.
    [Google Scholar]
  3. Hallof, P. G., 1972, The induced polarization method: 24th Int. Geol. Congr.9, 64–82.
    [Google Scholar]
  4. Hohmann, G. W., 1973, Electromagnetic coupling between grounded wires at the surface of a two-layer earth: Geophysics38, 954–863.
    [Google Scholar]
  5. Mundry, E., 1967, The vertical magnetic field of an alternating current dipole for horizontally stratified media: Geophys. Prosp.15, 468–479.
    [Google Scholar]
  6. Parasnis, D., 1966, Electromagnetic Prospecting—CW techniques: Geoexploration4, 177–208.
    [Google Scholar]
  7. Seigel, H. O., 1970, Induced polarization method: Mining in Canada, 1–13.
  8. Vogelsang, D., 1967, Geophysical prospecting in the Lake Victoria Goldfields: Geol. Rundschau56, 882–893.
    [Google Scholar]
  9. Vogelsang, D., 1972, Geophysical categorization of the Precambrian in South India: Geophys. Prosp.20, 317–328.
    [Google Scholar]
  • Article Type: Research Article
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