Numerical and Experimental Simulation of Reaction-Diffusion Processes in Metamorphic Rocks

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Several kinds of composite veins in serpentinite from the Nagasaki metamorphic rocks are investigated in terms of petrography and petrogenesis. Numerical simulation of reaction-diffusion equations together with mineral solubility data gives estimation of compositions of the fluid responsible for the formation of the composite veins.Mass transfer within serpentinite melange developing between serpentinite and pelitic schists and the resultant formation of albitite are examined. Comparison of bulk composifin of albitite and that of pelitic schists together with density data enables us to estimate the amounts of addition and subtraction in chemical components during the formation of albitite from pelitic schists. Major change in compositions is subtraction of SiO_2, MgO, CaO and FeO due to dissolution of quartz and actinolite in pelitic schists. Other components are immobile.The process of development of metamorphic layering based on uphill diffusion model is Simulated by Cell Dynamical Method. Local equilibrium between minerals and the intergranular fluid can enhance diffusion - coupling and cause uphill diffusion. Most metamorphic layering can be well explained by this model.Solubility of albite under hydrothermal conditions were experimentally investigated.