The Deep Lithospheric Structure of the South Australian Craton Revealed by Teleseismic Rayleigh Wave Tomography

We used teleseismic Rayleigh waves recorded by three recent broadband seismic arrays in southern Australia to develop a shear wave velocity model of the South Australian Craton from the lower crust to 250 km depth and compare this with isotope data, xenolith data, and 3D mantle resistivity structure. At ~75–150 km depth, the seismic expression of cratonic core lithosphere encompasses the eastern Gawler Craton, Curnamona Province, and intervening Adelaide Superbasin north of ~33°S. The inference of contiguous cratonic lithospheric mantle between the Gawler Craton and Curnamona Province may have implications for models of Rodinia breakup. Cratonic core lithospheric mantle is modelled as terminating substantially inboard of the conventionally-defined western margin of the Gawler Craton, but extending southward and northeastward beyond the conventionally-defined Curnamona Province boundary. Geophysical signatures of cratonic core lithospheric mantle are absent under the southern Eyre Peninsula, possibly related to the Jurassic–Cretaceous separation of Australia and Antarctica. At depths >150 km, the deep cratonic keel is restricted to the eastern Gawler Craton and southern Curnamona Province. Major iron oxide-copper-gold (IOCG) deposits of the eastern Gawler Craton (e.g., Olympic Dam) and Curnamona Province reside above the seismically fastest lithospheric mantle in the region. This seismic signature might provide a useful precompetitive vector for IOCG prospectivity mapping.