[S21-4] Lithospheric discontinuities II – Reflectivity

[S21-4-01] Multi-scale Structure and Lithospheric Discontinuities

^○Brian Kennett (The Australian National University, Canberra, Australia)

invited

The continental lithosphere is heterogeneous on a wide variety of scales and apparent seismic discontinuities arise from the interaction of the seismic wavefield with multiple-scale features. In consequence the character of such discontinuities is frequency-dependent, and interpretation in terms of simple structures can be misleading. Nevertheless it is possible to track discontinuities within the lithosphere across closely spaced stations exploiting P-wave reflectivity extracted from stacked autocorrelograms at each receiver.
Although most inference of finer-scale structure is indirect, corroborative evidence comes from the geochemistry of xenoliths across southeastern Australia. There is a close correspondence between changes in chemistry and P-wave reflectivity in the neighbourhood of the xenoliths.