上部マントルと地殼との相互作用-地質現象からみた上部マントル

概要

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Tectogenesis or the process of the evolution of the crust is discussed from physical and chemical view points. It is described by a coupling among tectonic deformation, vertical movement, igneous activity, and metamorphism. The upper mantle is a source of energy and material for the development of the crust. To obtain a quantitative picture of the evolution of the crust and the mantle, a method of energy analysis of geological phenomena is proposed and a few examples of results are presented.<BR>A model of heat-gravitational engine of tectogenesis is presented. Two varieties of tectogenesis, where the horizontal deformation and vertical movement of the crust are considered to have a primary significance respectively, are tested. It is shown that the mantle must behave as fluid for the former while as solid for the latter. In the latter hypothesis, a shift of center of gravity of the crust is significant.<BR>A significance of thermal convection within the upper mantle is studied by numerical analysis in relation to the process of tectogenesis. Inhomogeneity of the crust is assumed to be served as a trigger to generate activation of the upper mantle. Considering the time scale of actual tectogenesis, the effective viscosity of the upper mantle is estimated as 1021-1022 poises. A sequence of epiorogenic volcanism and the following plutonism is obtained theoretically.
社団法人東京地学協会の論文