摘要
Based on Fe-Mg distribution coefficient between olivine and melt, the MgO-FeO evolution diagram is built. The compositions of primary magmas can be estimated by the intersection point of straight line and curve which illustrates liquids in equilibrium with olivine. It is suitable for the system of olivine fractional crystallization, and its advantage is that it can be easily and visually used. It is also pointed out how the diagram is applied. The authors point out that most basalts from the Mount Emei large igneous province have MgO contents less than 8%, and include many clinopyroxene and plagioclase phenocrysts, suggesting that these basalts can not be directly resulted from olivine fractional crystallization of Mount Emei primitive magma.