Transient electromagnetic (TEM) test surveys have been made at various localities in Australia to evaluate the method. The test surveys described in this paper were made in the Rum Jungle, Mary River and Tennant Creek areas, Northern Territory. Good agreement was generally obtained between TEM results and those observed with other electromagnetic methods, and good correlation was obtained with geology. The theoretical advantages inherent in the method make it attractive under Australian conditions of conductive overburden, and field test results demonstrate these advantages. It was found that the TEM equipment could be used in areas where topography or highly conductive surface conditions severely limit the effectiveness of other geophysical methods. The use of large loops with sides 100-150 m enable large areas to be surveyed quickly, while smaller loops proved useful in delineating anomalies accurately. Different loop sizes with loop-overlap were used to assist quantitative interpretation. Transient electromagnetic scale modelling programs have also been made and two examples are given which demonstrate how interpretation can be improved by such programs. A model study of the Woodlawn copper-lead-zinc deposit indicated that the orebody would have been detected at depths of up to 200 m. Modelling an area known as the Gubberah Gossan in the Northern Territory demonstrated that the anomaly pattern could be caused by resistive quartz-sphalerite mineralization in a conductive carbonaceous shale unit.
