URANIUM: Geophysical signature of the Kintyre uranium deposit, Western Australia

Abstract

Kintyre is an unconformity-related, vein-style uranium deposit estimated to contain 36,000 t of U3O8. The deposit, located 70 km south of Telfer, was discovered during heliborne follow-up of 214Bi channel anomalies detected by an airborne magnetic and radiometric survey. Ground inspection of the strongest anomaly identified outcropping secondary uranium-silicate mineralisation. Drilling beneath the mineralised outcrop intersected the Kintyre ore lens, with the best hole containing 71 m at 5.94 kg/t U3O8. Since then, six additional ore lenses have been discovered and these make up the Kintyre deposit. A wide range of airborne, ground and borehole geophysical techniques has been applied to the evaluation of the deposit in an attempt to locate additional ore lenses and to determine a geophysical signature for use in regional exploration. Two types of geophysical signature have been determined for the deposit; that of the mineralised zones and that of the host unit. The deposit has an anomalous 214Bi channel radiometric response coupled with elevated counts in the potassium channel. Induced polarisation surveys have shown that a distinct, high apparent resistivity and high chargeability response coincides with the Kintyre mineralisation. The ore is hosted by a lithological package which contains variable amounts of magnetite, leading to a moderate- to high-amplitude, inhomogeneous magnetic response. A density contrast detectable by gravity surveying has been noted between the host sequence and surrounding rocks. Electrical surveys have shown that the host unit is resistive relative to the rest of the host sequence and other rocks in the area.