Phase equilibria in carbonic systems,and their application to freezing studies of fluid inclusions

Addition of CH₄ to CO₂ lowers the temperatures at which phase changes occur with respect to those in the unary system CO₂. At high density and high a melting interval of solid CO₂ can be expected. Rearrangement of currently available theoretical and experimental data permits bulk compositions of carbonic fluid inclusions to be determined from the final melting temperature of CO₂ and the degree of filling at that temperature. Homogenization temperatures of CO₂-CH₄ inclusions can be expressed in terms of equivalent CO₂-densities, permitting estimates of P-T relations using isochores in the unary system CO₂.