Ambient Noise Tomography for District-Scale Mineral Exploration Using Nodal MEMS Accelerometers: A Case Study from the Kansanshi Cu-Au Mine, Zambia

Abstract Metals are essential to the success of the energy transition, but the discovery rate of deposits has been in decline. Innovative new methods of exploration are required. In recent years, Ambient Noise Tomography (ANT) using passive seismic wavefields recovered from the background noise recorded by seismometers has gained increasing popularity as a tool in mineral exploration. Many studies have demonstrated its efficacy in mapping the local geological structure of mineral deposits, but have been limited to depths of a few hundred meters to a few kilometers and have focused on small lateral scales. The application of ANT for district-scale (tens of kilometers) exploration has remained untested. In this study, a network of 30 Sercel WiNG Micro-ElectroMechanical System (MEMS) accelerometers was deployed along a ∼50 km NE-SWline through the Kansanshi copper (Cu) – gold (Au) mine. The Kansanshi mine is the third largest copper mine in Africa, with a resource of 982.3 Mt of Cu (using a cut-off grade of 0.2% TCu) and 0.11g/tonne of Au as of December 2023. Here we show that ANT performed with cost-effective MEMS accelerometers can identify a significant body of metal source sediments beneath Kansanshi, with a thickness of multiple kilometres, as well as structures consistent with the expulsion of mineralizing fluid through focused zones. These results demonstrate that ANT using MEMS accelerometers would be a valuable tool for district-scale mineral exploration of greenfield sites.