Some comments on detailed magnetic investigations of ellipsoidal bodies at tennant creek

Abstract

The potential for magnetic prospecting in the Tennant Creek goldfield was established by Aerial, Geological and Geophysical Survey of Northern Australia (A.G.G.S.N.A.) investigations during 1934?1937. Copper, gold and bismuth mineralisation was shown to be associated with magnetite-hematite bodies, the most significant of these being the Warrego orebody. The exporation program carried out by Peko Mines was solely dependent on the magnetic prospecting method, and the magnetic ellipsoid model was chosen for the analysis and targeting of anomalies. Existing models at the time were not capable of matching the lenticular pipe-like shape, or of handling the demagnetising effects due to the high susceptibility of the bodies. Development of the ellipsoid model was carried out by Mr L.A. Richardson and C.B. Kirkpatrick. Geophysical analysis of the magnetic anomaly at Warrego demonstrates how the ellipsoid model was instrumental in development of the orebody. This includes the initial drill-hole target, a deep target, and also a residual target. Remanent magnetism tests and underground magnetic surveys are presently being carried out.