Application of ground-based B-field (TMI, TFMMR, TFMMIP and TFEM) surveys at Tropicana Gold Mine and pioneering of a comparable drone-based acquisition system

The Tropicana Gold Mine (TGM) is located north-east of Kalgoorlie, Western Australia and is the first significant gold discovery in the Albany-Fraser Orogen (AFO). Exploration to date has identified various areas of anomalous gold-in-basement outside of the immediate TGM mining centre; several of these prospects are the subject of ongoing exploration. At the Angel Eyes Prospect, the up to 40 m thick saline cover has historically hindered traditional electrical and electromagnetic geophysical techniques. The results of a galvanic source Sub-Audio Magnetics (SAM) survey showed a strong correlation with both known and newly discovered geological structures and accumulations of sulphides, both of which are related to gold mineralisation. A repeat drone-based B-field survey using a MagArrow™ receiver over Angel Eyes, hereafter referred to as MagnetoArrow surveys (definition includes the processing algorithms), has shown that this acquisition platform was suitable to acquire effective TMI (Total Magnetic Intensity), Total Field Magnetometric Resistivity (TFMMR), Total Field Magnetometric Induced Polarisation (TFMMIP) and Total Field Electromagnetic (TFEM) and has now been routinely used on a large scale at other TGM prospects. The MagnetoArrow results over two areas, C03 near Angel Eyes, and Salty Dog, are examined in relation to other geophysical and geological datasets. Continuous improvements have led to considerably enhanced survey speed and data quality of the MagnetoArrow system. This has greatly reduced the time and cost to acquire these data and holds numerous benefits for application in various terrains and on other deposit types. With the increased challenges of prospecting under cover, improved geophysical methods are sought. Grounded dipole B-field techniques have shown their value in providing information that would otherwise have been concealed.