Moho variations in the Archean Cratons of Australia from joint inversion of receiver function and Rayleigh wave group velocity
摘要
Non-linearity and non-uniqueness are two basic problems in receiver function (RF) inversion. Joint inversion of RF and surface wave group velocity data is often used to minimize these effects. Here, the advancement of joint inversion over others is discussed with synthetic RFs and observed RFs extracted from 43 broadband stations operated in three Archean Cratons of Australia, namely, the Pilbara, the Yilgarn, and the Gawler Cratons. Results show a thinner crust in Pilbara Craton (28–32 km) compared to the Yilgarn (36–40 km) and Gawler (38–44 km) Cratons. Average crust Vp/Vs is found to be lower (1.65–1.74) in Pilbara Craton, compared to Yilgarn and Gawler Cratons (1.67–1.80), suggesting a felsic crust beneath Pilbara to felsic-to-intermediate beneath Yilgarn and Gawler Cratons. Variations of Moho and Vp/Vs may be due to the difference in crustal formation, tectonic evolution, and lithospheric processes that could possibly affect the change in crustal properties. Pilbara and Yilgarn crusts show negative and positive correlations between Moho and Vp/Vs, respectively. The results obtained are compared with the Archean Cratons of India and Antarctica, and they support their Gondwana connection. We also observed a positive correlation between the stabilization age of these cratons and Vp/Vs, which is supported by global studies.