Physical properties and seismic imaging of massive sulfides

Laboratory studies show that the acoustic impedances of massive sulfides ca n be predicted from the physical properties (V-p, density) and modal abunda nces of common sulfide minerals using simple mixing relations. Most sulfide s have significantly higher impedances than silicate rocks, implying that s eismic reflection techniques can be used directly for base metals explorati on, provided the deposits meet the geometric constraints required for detec tion. To test this concept, a series of 1-, 2-, and 3-D seismic experiments were conducted to image known ore bodies in central and eastern. Canada. I n one recent test, conducted at the Halfmile Lake copper-nickel deposit in the Bathurst camp, laboratory measurements on representative samples of ore and country rock demonstrated that the ores should make strong reflectors at the site, while velocity and density logging confirmed that these reflec tors should persist at formation scales. These predictions have been confir med by the detection of strong reflections from the deposit using vertical seismic profiling and 2-D multichannel seismic imaging techniques.