3-D temperature and composition in the upper mantle constraint by global seismic tomography and mineral physics

3-D Shear velocity structure of the upper mantle proposed by modem global seismic tomographic models (e.g.Su et al., 1994) has striking correlation with global tectonic features.The dominating features in the upper mantle are low velocity domains which correspond to the oceans and high velocity roots of continental cratons which extend down to at least 400 km.It is remarkable that continental roots are not as well seen in the global gravity field.Recent advances in mineral physics make it possible to interpret these tomographic models and gravity data in terms of rocks composition and physical state.