FLUID-FLOW AND CHEMICAL-REACTION KINETICS IN METAMORPHIC SYSTEMS

The treatment and effects of chemical reaction kinetics during metamor phism are developed along with the incorporation of fluid flow, diffus ion, and thermal evolution. The interplay of fluid flow and surface re action rates, the distinction between steady state and equilibrium, an d the possible overstepping of metamorphic reactions are discussed usi ng a simple analytic model. This model serves as an introduction to th e second part of the paper, which develops a reaction model that solve s the coupled temperature-fluid flow-chemical composition differential equations relevant to metamorphic processes. Consideration of stable isotopic evidence requires that we consider such a kinetic model for t he chemical evolution of a metamorphic aureole. A general numerical sc heme is discussed to handle the solution of the model. The results of this kinetic model allow us to reach several important conclusions reg arding the factors controlling the chemical evolution of mineral assem blages during a metamorphic event.