SUMMARY OF CHARACTERISTICS AND SIGNIFICANCE OF THE MAGMATIC EPIDOTE

Abstract

Recent advances and geological significance of magmatic epidote(MEp) are summaried in this article. MEp stability in magma is firmly correlated with temperature, pressure, fH_(2)O and fO_(2). Crystallization sequence from magma of MEp depends on pressure but not fO_(2) . while,fO_(2 )can changes MEp minimum cystallization pressure from 5×10~8 Pa(fO_(2)=NNO)to 3×10~8 Pa(fO_(2)=HM). MEp which crystallized earlier than biotite or hornblende in the magma, can not be used as a barometer, but be useful in caculating the ascent speed of magma. Those MEp that occurred as subsolid mineral with or without resorption of earlier-formed hornblende, can be use as pressure indicator for intrusion. With respect to the influence of fO_(2), Granite can be subdivided into Magnetite and Ilmenite series. MEp that occurred in Magnetite series granite indicates the minimum pressure of 3kbar and 5kbar of Ilmenite series granite.