Mapping undercover domal structure using audio-magnetotellurics in Zambia.

Summary The increasing depth of investigation for sediment hosted copper mineralisation in the Central African Copperbelt requires the use of adequate geophysical methods such as natural source audio magnetotellurics (NSAMT) as opposed to conventional electrical geophysics techniques (resistivity/IP and time domain electromagnetics) which have limited depth of investigation. A NSAMT survey was carried out at the Solwezi East project near the Kansanshi copper mine in north-western Zambia in order to map a possible undercover domal structure which is thought to control mineralisation at the mine. A total of 50 line kilometres of NSAMT successfully identified a confined domal structure 1.2 km long and 700m wide buried at about 700m below surface. The mapped dome awaits a drill test to confirm the presence of economic mineralisation. NSAMT is proven to be successful for mapping buried domes at considerable depth.