Modern Conceptions about the Structure and Development of the Earth's Crust and Upper Mantle of Continents
The following are some of the important conclusions arrived at: (I) The so-called "basaltic layer" of the crust is actually a layer of degranitised metamorphic rocks of the granulitic facies (2) The thickness of the crust in geological history can change many times and such changes are in accordance with the changes of direction of the vertical crustal movements (3) The vertical tectonic movements are caused by processes not only in the crust, but in the mantle as well, and that the Upper mantie, undoubtedly, has horizontal inhomogeneities associated with the structure and movements of the crust (4) The most important peculiarity of Zone B of the Upper mantle is the presence of a waveguide in it, i.e. of a layer with reduced seismic velocities (5) An essential difference is marked in the relationship between the mantle and the crust in geosynclines, on the one hand, and on platforms, on the other.
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