広域変成作用と地殼の物理的性質

概要

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A process of regional metamorphism is physically interpreted as an interaction among heat flow, water flow and chemical reactions during a geosynclinal subsidence of the earth's crust. It is remarked that metamorphic rocks found in tectonic region represent an abnormal state of the crust of which mechanism should be surveyed from a geophysical view point. The following quantities are essential factors : rate of deformation or rate of subsidence of the crust (W), relaxation time of thermal equilibrium (τ_Τ), relaxation time of osmotic equilibrium (T_<os>), and rate of metamorphic reactions (J_c). The rate of geosynclinal subsidence is obtained as an order of 0.1 cm/year. The rock pressure is increased by several kilobars during an order of 10^7 years. Variations in temperature and water pressure during metamorphism of three model reactions are calculated. They are shown to be controlled exclusively by the reaction rate for W<0.1 cm/year. Actual features of metamorphic belts are interpreted in the light of the calculated results. A mechanism of generation of magma during metamorphism is briefly discussed.
地学団体研究会の論文
1961-03-25