Detailed study of partial melting process in the island-arc type high-temperature metamorphic terrane

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The main purpose of this research project is the detailed study of partial melting process and their related granitic magma producing system in the island-arc type lower crust as seen the high-temperature metamorphic terrane in Japan, the Hidaka metamorphic belt and the Higo metamorphic terrane. The results were compared with the typical high-temperature metamorphic terranes (Sri Lanka and Napier Complex, Antarctica). Brief results are as follows.1.Restarted the experimental work for dehydration melting of fluorine-biotite at the University of New South Wales, Australia. The stability field of the high-fluorine biotite expands into higher temperature side than fluorine-free biotite. Biotite of XF (F/ (F+Cl+OH) )=0.3 is still stable at 900 MPa, 1025ﾟC and those of XF=0.6 the stability field expand up to 900 MPa, 1075ﾟC.A part of the results were reported at the International Symposium on Antarctic Earth Sciences in Italy (Sep, 1995) and the International Geological Congress in China (Au … More g, 1996).2.Sixty days field research was carried out in the Higo metamorphic terrane, west central Kyushu. During the field work in 1995, the sapphirine-corundum and the garnet-corundum granulites were found in the central part of the terrane. This type of hyper aluminous silica-undersaturated granulite is known only in very (ultra) high temperature xenolith of Cortlandt Complex, USA.In the Higo metamorphic terrane, those granulites as the restite were derived from high temperature (>950ﾟC at 800-1000 MPa) dehydration melting of fluorine biotite (XF=0.2) -bearing metapelite. A part of the results was talked at the 1996 annual meeting of the Geological Society of Japan etc. and submitted to international journal.3.Sixty days another field survey was carried out in the Hidaka metamorphic belt to observe the details of partial melting of pelitic and mafic metamorphic rocks. Especially in the mafic metamorphic rocks it was identified that the bulk chemical compositions of amphibolites are clearly different between the north and the south of the belt. A part of the results was reported in the Memoir of the Geological Society of Japan. Less