Abstract

An underground test of a seismoelectric prospecting method for massive sulfides was performed at the Mobrun Mine (Rouyn-Noranda, Quebec) in June 1991. The method is based upon the conversion of seismic energy to high-frequency pulses of electromagnetic radiation by sulfide minerals. The delay between shot detonation and detection of the electromagnetic radiation gives a one-way traveltime for the acoustic wave to reach the zone of seismoelectric conversion, which when combined with P-wave velocity allows the shot-to-ore zone distance to be calculated. A 0.22-kg explosive charge located within 50 m of the orebody provided the seismic excitation, and the resulting electromagnetic emissions were received by electric dipole and induction-coil antennas.First-arrival information from a 35-shot survey above an orebody, the 1100 lens, provides firm evidence that short duration pulses of electromagnetic radiation are produced by the passage of acoustic waves through the orebody. The survey also demonstrated that seismoelectric conversions could be induced at shot-to-orebody distances of 50 m and detected at distances of up to 150 m from the orebody. Areas of seismoelectric conversion are highlighted in sections produced by plotting the position of seismic wavefronts during signal reception. The sections show anomalies that correlate with the known structure and location of the orebody and demonstrate the potential of using this seismoelectric phenomenon as an exploration tool.

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