Sedimentary and upper crustal structure of Australia from receiver functions

The initial coda of teleseismic P-waves contains considerable information a bout the crust and upper mantle structure directly beneath a receiver. When this information can be recovered for a dense network of seismographs much can be learned about the structure of the earth. Data from the high qualit y broadband seismic stations of the SKIPPY and KIMBA projects along with pe rmanent stations are used to investigate the upper crustal structure of Aus tralia. A dataset of 65 shear-velocity models derived from receiver functio ns has enabled the sedimentary and upper crustal structure of Australia to be summarised. Regions of thick soft sediment show good agreement with topo graphical lows. A simple relation between upper-crustal velocity and magnet isation, as has been suggested by other investigators, has not been observe d, but this may be due to the magnetic signal being muted by overlying sedi ments. A prominent mid-crustal discontinuity is apparent in the Tasman and New England mega-elements. This may represent a mid-crustal decollement tha t had structural control during accretion.