Western Tasmanian Regional Minerals Program (part 2): airborne electromagnetic data - quality control and interpretation

Recent regional scale helicopter electromagnetic (HEM) data acquired on the west and northwest coasts of Tasmania have demonstrated the powerful geological mapping capabilities of the HEM technique. Quality control for the survey was provided by analysis of repeat data from daily test lines, and comparison with surface geophysical data. Data have been interpreted by conductivity-depth imaging, complemented by layered-earth inversion of selected lines. The maximum depth of investigation for the HEM survey has been determined to be around 150 m, based on both theoretical calculations and the results of conductivity-depth imaging. A preliminary interpretation of the HEM data is presented for the Balfour region. The HEM survey has clearly differentiated previously unmapped units within the Proterozoic Rocky Cape Group, and has defined several major structural trends within the survey area. A large number of bedrock conductors have been identified in the HEM data, particularly close to the historic copper mining centre of Balfour.