Walt. Shame on you. Martin asked a very valid question and I think you may have caused confusion. Geophysicists have no trouble interpreting EM, gravity, IP, seismic, and magnetic surveys. Geophysicists have spotted or drilled all of the discovery boreholes in Voisey's Bay. Companies that have geophysicists DO NOT have any trouble interpreting what it all means (i.e., note that DFR and INCO had/have geophysicists on staff and have drilled all of the nickel-copper-cobalt orebodies found to-date in Labrador.) Most major mining companies do not allow geologists to interpret geophysical anomalies--can you guess why??
Geologists, prospectors, and/or engineers often have trouble trying to interpret (or make sense of) geophysical anomalies. The solution is obvious; prosperous companies employ geophysicists to find the massive-sulfide orebodies. Geologists, prospectors, and engineers can be very nice (as they often curtsey to management-types), but IMNSHO to make any nickel discoveries in Labrador requires a geophysicist with nickel-copper massive-sulfide experience.
Mr. Dee, Walt was right about many things. EM does detect conductive minerals like pentlandite, chalcopyrite, pyrrhotite, and graphite. Gravity detects heavy or dense minerals like pentlandite, chalcopyrite, magnetite, and pyrrhotite. Magnetics detects magnetic minerals like magnetite and pyrrhotite. So it's kind of simple--to detect Voisey's Bay-type nickel mineralization (i.e., pentlandite, magnetite, pyrrhotite, and chalcopyrite) you need an EM conductor, a magnetic high, and a gravity high. Geophysical interpretation is just interpreting the where. the geometry, and volumetrics of economic mineralization (i.e., ORE) --drilling then just confirms or contradicts what the geophysicist has previously interpreted.
Be aware that Mother Nature often seems to love to humiliate humble geophysicists and geologists and engineers. Orebodies are like beautiful women--they reveal their secrets slowly <grin>.
Regards, T. |
