3D ISOCHRONAL MODELING OF REFLECTIONS FROM THE DEEP CRUST - APPLICATION TO REFLECTION PROFILING IN CENTRAL AUSTRALIA

Reflection profiling of the whole crust across ancient terranes encounters a range of interpretational problems and ambiguities, especially with regard to the geometry of faults. Such problems can be addressed by Seismic modelling with full inclusion of diffractions and a suitable modelling procedure for such three-dimensional problems is the isochronal technique described by Cao and Kennett (1989). Such modelling has been used to investigate the validity of some of the interpretations of a deep crustal refection profile in central Australia involving planar faults of moderate dip penetrating most of the crust and considerable Moho topography. Even with a relatively short (4 km) field spread it would be possible to detect the reflected energy from faults with dips of about 40°. The character of the reflections also suggests considerable variability in piysical properties within the fault zones. The largest fault, the Redbank Zone, has significant displacement of the Moho. But most of crustal faults appear to sole out into the crust-mantle interface. This gives rise to an undulating Mcho for which Seismic modelling corresponds closely to the observed data. © 1990.