Improving Nickel Exploration using a Purposefully Designed Airborne Electromagnetic System, with an Example from Julimar, Western Australia

Nickel (NiS) exploration is well suited for geophysical methods; nickel sulphides are generally dense, very electrically conductive and chargeable. In particular, electromagnetic methods are suitable because of a very large conductivity contrast between nickel sulphides and host rocks. The extreme conductivity of massive NiS can cause the decay constant of a potential resource to be very large (Smiarowski and Macnae, 2013), necessitating low-base frequency or ground EM surveys. Ground EM surveys can be time-consuming, very costly, and suffer in difficult to access terrain. In the last 5 years, advances in receiver suspension and receiver construction have made airborne electromagnetic low-base frequency operation possible and greatly improved the ability to explore for NiS. We discuss the changes made to the Xcalibur Helitem, helicopter time domain EM, system to enable low base frequency operation at 6.25 Hz. We then show an example of a low base frequency Helitem survey targeting Nickel performed in the Julimar Region of Western Australia. Of particular interest is the detection of anomalous conductivity outside of the magnetic extent of the Julimar Complex.