Airborne EM applied to sulphide nickel ? examples and analysis

Abstract

Exploration for nickel sulphides has often involved the application of airborne electromagnetic data. Some of the early successes of the technique were in Canada in the 1950s, detecting shallow massive sulphides in highly resistive host stratigraphies. As exploration for deeper deposits under cover proliferates, a comparison of different systems and an analysis of the depth of penetration of these systems is required. An examination of field data from three known nickel sulphide deposits shows that the target anomalies are all above the noise level except where shielded by a flat-lying conductor. Using the geological models for each deposit, forward modelling was applied to determine that the ore bodies chosen for this study could be buried deeper before the system used would cease to be an effective exploration tool. Forward modelling also shows that all methods examined are able to identify the target. Systems with lower base frequency and wider transmitter pulse give the best results.