Survey results from ground IP-Resistivity, Spectrem airborne electromagnetics and magnetics, and ZTEM™ tipper AFMAG helicopter electromagnetics are compared over the Pebble porphyry copper deposit, in southwest Alaska. The IP data display higher amplitudes associated with the increased sulphides over the Pebble alteration halo that vector towards the deposit. Lower resistivities are associated with the chargeable alteration halo and slightly higher resistivities occur in the less chargeable core at Pebble West. The deeper Pebble East was not detected in IP due to insufficient penetration. The airborne EM surveys, Spectrem and ZTEM, appear to map the resistivity contrast with more resolution than the ground IP resistivity survey, due to higher sampling and better depth of investigation. Spectrem conductors coincide with the rich pyrite mineralization, sulphide veins and alteration, but the depth of investigation is at the detection limit of Pebble East. The ZTEM tipper AFMAG survey appears more sensitive to weak resisitivity contrast especially at depth. Both Pebble West and East are well detected in the ZTEM results.
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