Lithospheric resistivity structures and mineral prospectivity from AusLAMP data in northern Australia

Magnetotelluric (MT) data allow geoscientists to investigate the link between mineralisation and lithospheric-scale features and processes. In particular, the highly conductive structures imaged by MT data appear to map the pathways of large-scale palaeo-fluid migration, which is an important element of several mineral systems. New data were collected as part of the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) under Geoscience Australia (GA)'s Exploring for the Future (EFTF) program in northern Australia. We use this dataset to demonstrate that the MT method is a valuable tool for mapping lithospheric-scale features and for selecting prospective areas for mineral exploration. Given the importance of MT data, Geoscience Australia, state and territory geological surveys, and research organisations have united under the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) to collect long-period MT data across the continent on a ~55 km-spaced grid (Figure 1). Our results image a number of major conductive structures at depths up to ~200 km or deeper in the survey region, for example, the Carpentaria Conductivity Anomaly east of Mount Isa and the Tanami Conductivity Anomaly along the Willowra Suture Zone. These significant anomalies are highly conductive lithospheric-scale structures, and show spatial correlations with major suture zones and known mineral deposits. These results provide important first-order information for lithospheric architecture and identifying the broad footprint of mineral systems. Large-scale crust/mantle conductivity anomalies that map fluid pathways associated with major sutures/faults may have implications for mineral potential. These results provide evidence that some mineralisation occur at the gradient of or over highly conductive structures at lower crustal and lithospheric mantle depths. These observations provide a powerful means of highlighting greenfields for mineral exploration in under-explored and covered regions.