Massive sulphide delineation using borehole radar: tests at the McConnell nickel deposit, Sudbury, Ontario

Ground-penetrating radar (GPR) surveys were undertaken in three boreholes i ntersecting the McConnell massive Ni-Cu sulphide deposit near Sudbury, Onta rio, Canada. Radar data were acquired using single-hole and crosshole confi gurations to assess the potential in delineating massive sulphide deposits. Single-hole radargrams acquired with 22 and 60 MHz antennae display reflec tions from the upper and lower boundaries of the deposit in areas where the contact between the host rock and ore body is sharp. Direct arrival travel times selected from crosshole measurements between two shallow boreholes we re used for tomographic reconstruction of inter-hole velocities. The crossh ole data set also contains late arrival reflections from the ore deposit. T he reflections were migrated using the velocity distribution obtained from tomography, to estimate the position of the upper surface of the deposit be tween the two boreholes. The deposit is imaged over a small area near its i ntersection with a shallow borehole. The survey geometry could not provide information on the position of the ore body at mid-distance between the bor eholes, i.e. in areas of most interest to geologists. (C) 2001 Elsevier Sci ence B.V. Ah rights reserved.