An appraisal of the VLF ground resistivity technique as an aid to mineral exploration

To assist the Department of Industry Mineral
Reconnaissance Program (DIMRP) limited research
has been undertaken to provide guidelines on new
geophysical prospecting systems, field techniques
and general exploration methodology.
A short study has been made of the ground
VLF resistivity (VLF-R) method to assess its
potential for mineral prospecting and geological
mapping. Field trials confirm that the method is
well suited for mapping broad mineralised zones,
flat lying conductors of limited lateral extent, or
abrupt changes in conductivity associated with
geological contacts. In resistive terrains the method
offers distinct operational advantages over galvanic
resistivity methods. The principal disadvantages of
the technique relate to interpretational ambiguities
associated with the complex behaviour of surface
impedance at VLF and the fact that the operator
has no effective control over the depth of investigation.
Theoretical model studies show that too
small and too large a penetration can both result
in non-detection of a resistive target, but that
excessive penetration will not seriously affect the
resolution of conductive targets.