Problems of Global Geodynamics

Global geodynamics is determined by the thermal convection in the mantle which manifests itself on the surface by movements, relief, heat flow, and volcanism. Thermal convection in the Earth is complicated by the fact that the lithosphere is broken into rigid plates, the crust is broken into six separate floating continents and a number of islands, on the mantle bottom there are two giant piles of heavy material, at high intensity the ascending convective flows acquire a plume shape, and phase transformations take place in the mantle. The influence of many factors on the mantle structure has been studied in detail and substantially understood. It is topical to reconcile the new data about phase transformations at depths of 650 to 700 km with the seismic data about the positions of these boundaries. The ultimate problem of global geodynamics has not yet been solved; the three-dimensional structure of the whole-mantle flows, consistent with the observations in geophysics, geochemistry, geology, and numerical modeling is not known even on a semischematic level.