Spartan MT (magnetotelluric) for Deep Target Evaluation at the Historic Warrego and Juno Mines, Tennant Creek

Abstract

Audio Magnetotelluric surveys for Tennant Mining were acquired in October 2025 at the Juno and Warrego mine areas, at 100m and 200m station spacing. The data was of good quality and successfully inverted to produce robust 2D and 3D models of resistivity (Anne Tomlinson, 2026). The surveys successfully mapped broad lithological and structural trends and, when integrated with drilling, mine lode models, and magnetics data, identified six areas of interest for possible exploration follow-up - four at Juno and two at Warrego. It is recommended that these areas are reviewed using all available geological and geophysical datasets. Both Juno and Warrego display a systematic increase in resistivity with depth, interpreted as an artefact of shallow weathered bedrock conductivity influencing the deeper inversion response and effectively shielding deeper responses. No discrete conductive anomalies attributable to known mineralisation were identified. This may have been further hindered by a lack of conductivity contrast with host rocks over the volume required for detection with MT, combined with a reduction in volume of material from historic mining.