3-D Crustal structure of Mount Isa, metallogenic province in Northern Australia from ambient noise tomography

Abstract

Summary The Mount Isa Province in northern Australia represents one of the largest exposed Proterozoic crustal regions within the Australian continent and is recognized globally for its world-class mineral deposits. The underlying crustal architecture has been investigated using a series of geophysical profiles informed by geological mapping, gravity, magnetic, magnetotelluric, and seismic data. In this study, we reanalyze legacy passive seismic data recorded across the entire province to generate a high-resolution crustal shear wave velocity model using ambient noise tomography. These results are interpreted alongside reflection seismic profiles acquired along the same survey lines to provide complementary constraints on crustal composition, also with an association of surface geology. Our model reveals distinct velocity contrasts at some major crustal boundaries, including the Gidyea Suture Zone and several major fault zones. Mapped upper crustal intrusive bodies based on seismic reflections appear to cluster around high-velocity anomalies at 5 km depth in our model, and they seem to be linked to the broader higher velocities within the Mount Isa Inlier at 15–20 km depth. These fast, mid-to-lower-crust features probably represent mafic intrusions associated with a trans-lithospheric magmatic system that also involves felsic volcanism and associated metallogenic activity across the broader region. The research results of this area show how passive seismology can be integrated with other geophysical datasets to improve our understanding of fundamental structures for large mineral deposit systems worldwide.