THERMODYNAMIC CRITERIA FOR LIQUID IMMISCIBILITY IN VOLCANIC ROCKS OF THE BASALT-RHYOLITE ASSOCIATION OF THE RUDNYY ALTAI RANGE

Abstract

A method is presented for determining the thermodynamic effect of the separation which makes it possible to analyze each system as a whole and to plot the change in free energy produced by separation into immiscible phases. This technique was used to calculate the compositions of parent melts that separated into phases, including the melts that produced certain volcanic complexes of the Devonian ore-bearing basalt-rhyolite association of the Rudnyy Altai range. It is shown that the proposed method of analyzing changes in the Gibbs free energy resulting from separation of immiscible phase gives a more detailed picture of the possible relationships between the separating phases. Its application to volcanic products of the basalt-rhyolite association of the Rudnyy Altai has produced new confirmation that immiscibility in the parent melt plays a significant role in the evolution of orebearing volcanic complexes.