Experimental and Analytical Studies on Partial Melting Structures of the Upper Mantle and the Lower Crusts

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The purpose of this project was to investigate the mechanisms of melting reactions, solid-melt separations and the magma generation through the observation and analysis of mantle-derived ultramafic rocks and migmatitc rocks occurring in high-temperature metamorphic terranes. For this purpose, we purchased in the first year an scanning electron microscope and in the second year, introduced an energy dispersive energy analysis system and assembled them as an energy dispersive electron microanalyzer system. Significant efforts were made to improve the accuracy and precision of the microprobe analysis. Other research achievements made during the research period are as follows : (1) Studies on the Horoman peridotite. Two papers were published in international journals. Characterization of inhomogeneity structure are being made in terms of major and trace element chemistry. (2) The tourmaline-out isograd have been established in the Ryoke metamorphic terrane, Aoyama area, Mie-Prefecture. The destabilization reaction of the tourmaline and the material transfer associated with the partial melting of rocks were investigated. The result have been published in one paper. (3) Geochemical data have been obtained for the migmatite and granitic rocks from the Higo metamorphic terrane, Kyushu. (4) Dehydration melting texture observed in a granitic xenolith enclosed in basaltic lava have been investigated. The results are written in a paper , which is in preparation for submitting to a journal. (5) A theoretical study was made on the rheology of partially molten granitic rocks and a critically review was made for the "Rheologically Critical Melt Percentage (RCMP) concept. The paper is submitted for possible publication in an international journal.