New insight into Cainozoic sedimentary basins and Palaeozoic suture zones in southeast Australia from ambient noise surface wave tomography

Detailed images of Rayleigh wave group velocity are derived from ambient seismic noise recorded by WOMBAT, a large rolling seismic array project in southeast Australia. Group velocity maps sensitive to crustal structure exhibit low velocity anomalies in the presence of sedimentary basins and recent hot-spot volcanism, and high velocities in regions of out-cropping metamorphic and igneous rocks. Distinct and well-constrained patches of low velocity within the Murray Basin provide new insight into the spatial extent and possible composition of pre-Tertiary infra-basins. In a broader tectonic context, our results show little evidence for the Palaeozoic building blocks of the southeast Australian continent that have been inferred from geological mapping and potential field data. This may mean that apparent changes in basement terrane near the surface are not associated with major changes in composition at depth.