Local mineral equilibrium in metamorphism: development of D. Korzhinskii’s ideas (on 110th anniversary of D.S. Korzhinskii)

In 1950, D. Korzhinskii hypothesized that minerals in metamorphic reactions can be in local equilibrium. Proceeding from this idea, G. Fisher and R. Joesten later developed a realistic model of metamorphism kinetics. The model included diffusive mass transport in intergranular fluid controlled by the concentrations of components and chemical potential gradients, local-equilibrium reactions between minerals and pore fluid, mass balance of components, etc. The Korzhinskii–Fisher–Joesten model can provide clues to the duration of metamorphic events as inferred from mineral chemistry, free energy of phases, and rock textures and structures. The respective modeling of metamorphic reactions, with regard to spatial distribution of mineral grains, has implications for the transport and balance of chemical components. The balance of components (except volatiles) is restricted to domains of hundredth fractions of a cubic millimeter to several cubic meters. This may be the minimum size of an elementary domain in which minerals are in local equilibrium.