The Activities of Components in Natural Silicate Melts

Abstract

In a series of papers, Carmichael and his co–workers have applied the thermodynamics of heterogeneous equilibria to igneous processes for two ends. First, thermodynamics can be used to describe the activity or effective concentration of components in silicate melts. This in turn, provides a quantitative basis for characterizing or classifying igneous rocks. This topic has been discussed in detail by Carmichael et. al. (1970, 1974). Second, the thermodynamics of heterogeneous equilibria can be used to estimate pressures and temperatures of equilibration between melt and solid phases (Nicholls et al., 1971; Nicholls and Carmichael, 1972; Bacon and Carmichael, 1973; and Carmichael et al., in press).