Geophysical Investigations of the Fortnum Gold System, Western Australia

The Fortnum gold deposit is a structurally controlled gold system hosted by Lower Proterozoic sedimentary and volcan- iclastic rocks of the Glengarry Group in the Glengarry Basin of Western Australia. Geophysical techniques applied at Fortnum include ground and airborne magnetics, resistivity, induced polarisation and gravity. Magnetic and resistivity data enabled extrapolation of geological information to areas concealed by transported cover, and the interpretation of structures believed to have influenced gold deposition. Magnetic and gravity data delineated several features for which geological explanations remain speculative. The application of geophysics did not detect mineralisation, nor was it expected to, but has been a valuable tool in advancing our geological knowledge of the system.