The heterogeneous mantle

Rocks are composed of heterogeneous mixtures of minerals and assemblages of larger units, and there is no reason to assume that the Earth at large and intermediate scale should be homogeneous. However, the resolution of geophysical studies of the Earth's mantle is limited. There is a gap in resolution between studies of rock samples brought to the surface of the Earth and seismological results, which mainly show large-scale structures. There is also a gap between global tomographic models and the results of high resolution body wave and scattering techniques. It is often assumed that the mantle is homogeneous at intermediate scales. The standard model of geochemistry, for example, assumes that the upper mantle is homogenous.