Experimental Study On Partial Melting Of Lherzolite From Damaping

Partial melting experiments have been carried out at 1.0-3.0GPa and 1350～1550℃ using lherzolite from Damaping region as starting material. All experiments under high-pressure and high temperature are quenched to acquire silicate melt(glass). The component of the samples after experimented are studied. In the system of lherzolite, the phase equilibrium of lherzolite under high-pressure and high temperature has been preliminary determined. The migration of major elements has been revealed during partial melting. The relationship between pressures and structures of silicate melts is found and it is used to explain the properties of silicate melts. The relationship between partial melts formed from lherzolite and Damaping basalts is discussed in this paper, which is used to discuss the origin of Hannuoba basalts. The compositions of the melts from lherzolite obey the rules as followed: The MgO contents of partial melts Variation is more sensitive to changing degree of melting than to pressure. It's also mentioned that SiO₂ decreases with increasing MgO at low MgO contents, particularly at 0.5 and 1.0GPa. It's evident that the Mg# of the source peridotites controls the FeO contents of partial melts. The CaO/Al₂O₃ ratio of partial melts increasing with increasing degree of melting of lherzolite. Hannuoba basalts from Damaping have a clinopyroxene trend, which are the same as the melts in this partial melting experiments. It's implied that if the source is lherzolite, the basalts have a evolution trend from olivine basalt to basalt.