Low-calcium, high temperature granitic magmas are common where the earth's crust has been extended. The crystallization of such high temperature magmas cannot be completely characterized by the usual approaches. It is proposed here to conduct a theoretical and experimental investigation of this kind of magma. As the first stage of a major experimental and thermodynamic investigation of the effect of Fe on the phase relations in the sodic regions of the feldspar system, phase relations in a system containing the mineral fayalite will be determined. These results will be used to evaluate of the thermoynamic mixing behavior of fayalite in melts and the stability relations in many granite magmas.
