広域変成作用における水の役わりと地殼の物理的性質

概要

論文の詳細を見る
A role of water in regional metamorphism is studied from a physicochemical aspect of the crust. It is assumed that the water squeezed out from a high grade metamorphic zone by dehydration migrates towards a low grade zone to give a source of hydration there. A thermodynamical coupling among hydration-dehydration, heat and water transfers is discussed based upon a theory of thermodynamics of irreversible processes. The transfer of water is assumed to be in a form of hydrodynamical flow through porous media. Physical causes of metamorphic processes are classified into (1) a heat concentration and (2) a stress concentration. Chemical conditions are classified into (A) a fast reaction rate and (B) a slow rate. The main results are as follows : (Case 1A) A pressure gradient is determined by an ordinary CLAPEYRON-CLAUSIUS equation and the high grade zone becomes wide with a rate of 3 km per 1 million years for reasonable physical constants. (Case 1B) A pressure gradient approaches zero for any given temperature gradient and the zone boundary does not move. (Case 2A) A temperature gradient is determined by an ordinary CLAPEYRON-CLAUSIUS equation and the high grade zone becomes narrow with a rate of 45 km per 1 million years. (Case 2B) A temperature gradient approaches zero and the high grade zone become narrow with a rate of 10 cm per 1 million years. A variety of widths of metamorphic zones for different metamophic processes depends not only upon magnitudes of pressure or temperature gradient but also upon external conditions to fix gradients. Consequently a simple analysis of zone mapping is difficult. The transfer of water due to a diffusion seems to be less effective than that due to a hydrodynamical flow even at a deeply hurried zone.
地学団体研究会の論文
1960-01-25

広域変成作用における水の役わりと地殼の物理的性質

スポンサーリンク

概要

著者

関連論文

スポンサーリンク