Abstract

Laboratory measurements of the density (rho ) and compressional wave velocity (v P ) of massive sulfides and host rocks at elevated pressures show that ores occupy a V P - rho field which is distinct from that of common silicate rocks and governed by simple mixing rules between the properties of host rocks and pure sulfide minerals. The velocities of the most common sulfides are extremely variable, ranging from 3.7 km/s for galena, through 4.7 km/s for pyrrhotite, 5.6 km/s for sphalerite and chalcopyrite, to 8.0 km/s for pyrite, but their densities are always high (7.6, 4.6, 4.1 - 4.2, and 5.0 g/cc, respectively), causing ores of even intermediate grade to have high acoustic impedances. This suggests that large massive sulfide bodies should make strong to spectacular seismic reflectors, depending on their grade, mineralogy, size, and setting. In principle, it should thus be possible to use high-resolution seismic reflection techniques for base metal exploration and delineation.

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