Tests of piezoelectric and pulsed‐radio methods for quartz vein and base‐metal sulfides prospecting at Giant Yellowknife Mine, N. W. T., and Sullivan Mine, Kimberley, Canada

Abstract

In the summer of 1983, G. A. Sobolev and V. M. Demin of the U.S.S.R. came to Canada to demonstrate techniques using piezoelectrical and other mechanoelectrical effects for in‐mine geophysical surveys. We performed field trials using Soviet and Canadian equipment in the Giant Yellowknife Mine, N. W. T., and the Sullivan Mine, Kimberley, B.C., Canada. The principle of the technique involves detonating an explosive charge and subsequently measuring the strength and delay time of electromagnetic fields generated by excited minerals. Ore grade gold zones at the Giant Yellowknife Mine occur within large quartz lenses in a shear zone in Archean volcanics. Our tests there produced strong signals in the 8 kHz range, which were very similar to piezoelectrical signals produced by quartz samples, in the laboratory at the University of British Columbia. The Sullivan orebody is a 160 million ton iron‐lead‐zinc sulfide deposit lying comformably in Proterozoic rock. Our tests there yielded some very strong electromagnetic signals with frequencies as high as 350 kHz. The short delay times of these signals preclude any possibility that the signals were simple seismic phenomena generated at the antenna sites. Sobolev et al., (1982a, b) suggest that such high‐frequency signals are produced by a highly nonlinear discharge phenomenon occurring at the grain boundaries of naturally occurring semiconductors such as galena, sphalerite, and pyrrhotite.

Modeling of seismo-electromagnetic phenomena

“…But because of residual orientation of the quartz grains some rocks will show a larger piezolectric effect [Ghomshei and Templeton, 1989], although still perhaps two to three orders of magnitude less than in monocrystalline quartz [Bishop, 1981]. The piezolectric properties of rocks have been widely studied in the context of geophysical prospecting [Kepis et al, 1995;Neyshtadt et al, 1972;Sobolev and Demin, 1980;Sobolev et al, 1984]. Changes in polarization can be related to the strain tensor via…”

“…Creation of an electric field by the passage of a seismic wave through soil has been observed [Eleman, 1965;Ivanov, 1939;Leland and Rivers, 1975;Martner and Sparks, 1959]. These seismo-electric effects have been applied to geophysical prospecting [Kepis et al, 1995;Sobolev and Demin, 1980;Sobolev et al, 1984;Thompson and Gist, 1993].…”

SEISMO‐ELECTRIC EXPLORATION: EXPECTED SIGNAL AMPLITUDES1

“…In general, calibrations are not available in the published records. The joint experiments (Sobolev et al 1984) used equipment .for which we do not know the calibrations. In our own experiments we know the instrument calibrations but most of our measurements are dominated by higher-frequency responses, presumably including PRRER, and the identification of true piezo-electric responses has proved difficult.…”

“…Sobolev and Demin 1980) have been publishing papers describing the conversion of seismic energy to electric and magnetic signals by certain types of mineral bodies. In 1983, Sobolev and Demin brought their equipment to the University of British Columbia and demonstrated its capabilities in joint experiments at two mines in western Canada (Sobolev et al 1984). Since then, our own experiments have demonstrated both electric and magnetic signals when small explosive charges (less than 3 kg of forcite) were detonated near known or suspected target veins at several other mines.…”

Geophysical exploration for gold—A review

“…Sobolev et al (1984), of the Soviet Union, have experimented with piezoelectric and other mechanoelectrical effects for in-mine surveys. Tests were carried out at the Giant Yellowknife Mine in Canada in 1983, Where ore-grade gold zones occur within large quartz lenses in a shear zone in Archaean volcanics.…”