ABSTRACT
A budget of the heat lost from the mantle can be prepared if one develops a thermal model that simulates the processes of ocean-floor spreading, ocean-crust cooling, subduction, and intraplate volcanism. The boundary between the Earth's mantle and core is probably the most fundamental interface within the planet. The heat that reaches the surface of the planets comes from the Sun and from the interior of the planets. On Earth and the inner planets most of the heat comes from the Sun. The upper mantle gains heat and volatile components from a convecting lower mantle that is traversed by mantle plumes. A variety of indirect methods have been used to investigate the modal and chemical composition of the upper mantle. The compositions of some samples of upper mantle rocks have been modified by metasomatic processes. Samples of the upper mantle show that beneath continental areas it is mineralogically complex and chemically heterogeneous.
