OIB-type picritic porphyrite from Jianchuan in the western Yunnan Province: Results of break-off of the subducting plate?
滇西剑川OIB型苦橄玢岩:俯冲板块断离的产物?

Small scale OIB-type picritic porphyrite,comprising olivine,clinopyroxene and plagioclase,outcrops in Jianchuan area,western Yunnan,and the olivine is predominantly chrysolite with the Mg# up to 88.8.The bulk-rock composition is characterized by relatively low SiO2(43%~48%) but high MgO(12%~24%) content.On the basis of the principle of the olivine-melt equilibrium,we conclude that their parental magma is picritic(MgO=13%,FeO=10%).The normalized rare-earth element(REE) patterns of picritic porphyrite is simi...