Some models for the rate of crystallization of garnet in metamorphic rocks

Abstract

Information on the form of the equation for the rate of crystallization of garnet in metamorphic rocks may be obtained by combining an expression for the rate of crystal growth, obtained from data on compositional zoning, with an expression for the rate of nucleation, obtained from the crystal-size distribution. Three models for the rate of crystal growth and four for the rate of nucleation are formulated, and these, in different combinations, give rise to ten models for the rate of crystallization. Considerable variation in the form of the growth and nucleation equations produces a relatively small variation in the form of the equation for the rate of crystallization. In the favoured crystallization models, the volume of garnet produced in unit volume of rock is a function of time raised to the power m, where m lies between 3.5 and 5.