Case Studies - Mineral Exploration

Stillwater Complex, Montana - Platinum/Palladium

Presented here, are the total magnetic field, EM susceptibility and 7200 Hz resistivity data from a DIGHEM helicopter electromagnetic survey for Idaho Consolidated Metals Corporation, over the Stillwater Complex in Montana. The survey covered the JM Reef platinum/palladium deposit and Idaho Consolidated's properties surrounding the deposit.

Total Magnetic Field

The magnetic and resistivity data were useful for delineating the extent of the massive sulphide Cu-Ni bearing zones and conductive mineralised marker horizons in the Stillwater complex.

7,200 Hz Apparent Resistivity

The EM susceptibility map was created from a proprietary algorithm that calculates the magnetic susceptibility from the inphase and quadrature electromagnetic amplitudes (Huang and Fraser, 2000). The EM susceptibility has the advantage over the total magnetic field, in that the anomaly strengths and locations are less affected by dip and are independent of remanence and the inclination of the magnetic field. The EM susceptibility also presents a useful measure of the magnetic properties of the rocks at the usual depths of interest for mining exploration, as opposed to the mixture of deeper and near surface information in the total field magnetic data. The EM derived susceptibility can also be used to correct the apparent resistivity for the effects of magnetite.

EM Derived Susceptibility

A more detailed discussion of the results of the survey can be found in Idaho Consolidated's press release at www.montanaplatinum.com.

Also check out the following technical paper:
Airborne resistivity and susceptibility mapping in magnetically polarisable areas.