Sr and Nd isotopic constraint to the formation of migmatites from the Higo metamorphic terrane, Japan

抄録

Sr and Nd isotope compositions of migmatites and leucogranites in the highest grade zone of the Higo low-P /high-T (andalusite-sillimanite type) metamorphic terrane, central Kyushu, Japan, suggest that the nebulitic migmatites (diatexite) formed by melt infiltration into the pelitic gneisses, and the stromatic migmatites (metatexite) by in situ partial melting of the pelitic gneisses. The nebulitic migmatites preserve a record of large magnitude Sr and Nd isotope disequilibrium with the pelitic gneisses, which show the isotope equilibrium with the stromatic migmatites.