AusArray: uncovering major crustal features using passive seismic data

It is generally accepted that improvements in mineral exploration are required to meet the rising demand for minerals associated with a transition to lower carbon energy sources. There is growing consensus in mineral exploration that the distribution of fertile mineral camps is controlled by major lithospheric structures yet there is a paucity of case studies with adequately distributed datasets to test this view. Here, we test the relationships between variations in the Mohorovii discontinuity (Moho) and iron oxide-copper-gold and sediment-hosted mineral deposits in the regions between the Arunta and Mount Isa Provinces. We primarily utilise datasets from the Australian passive seismic array (AusArray) and preexisting academic seismometer deployments supplemented by deep reflection seismic profiles. The 55-70 km seismometer interstation distance provides almost continuous imaging of the Moho interface using backprojected receiver functions. We observe the Moho surface undulates at depths of ~35 to ~50 km, reflecting the complex regional tectonic framework of the area. Sharp steps are observed associated with major crustal boundaries such as the Willowra Suture and the Cork Fault, while other changes are more gradual but on the first order correspond to lithospheric thickness variations. Inspection of the Moho surface and the spatial distribution of base metal deposits suggests that significant deposits (>2 Mt) are distributed along the edges of second-order north-south to northeast-southwest-trending thicker crustal blocks. Our results indicate that passive seismic methods are a powerful tool to generate continues datasets across large regions from which important architectural features can be identified to support exploration under cover in frontier regions. Higher-resolution seismic surveys would be useful to link these structures with mineral camps in the near surface.