Progressive change of mineral composition in metabasite along low- to high-P/T metamorphic facies series

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It has long been well-known since late 1950s' that metabasite is more sensitive than metapelite to the change of metamorphic grade at t lower than 400 ゜C. However, such characters of metabasite and itsmineral composition have been clarified after 1980 by the extensive use of microprobe. This Project belongs to this flow of study, and is composed of three parts; experimental petrolgy, study of metamorphic belt, and related tectonics.In part I, petrogenetic grid of metamorphic facies was determined at P<10kb, and T>500 ゜C at Stanford University. The facies boundaries bewteen zeolite and prehnite-pumpellyite(PP) facies, PP and pumpellyite-actinolite(PA) facies, PA and greenschist(GS) facies, prehnite-actinolite facies and GS facies, and blueschist and GS facies. In addition, the thermodynamic calculation of the sliding equilibria by the introduction of ferric iron for such transition was achieved.In part II, the progressive change of mineral composition with increasing metamorphic grade along the lowest P/T facies series(Karmutsen, Vancouver island, Canada), high-pressure intermediate facies series(Sanbagawa belt, Japan), and highest-P/T of Franciscan, California, were studied. A comprehensive summary was also achieved.In part III(application of this study), the uplifting tectonics of the deep-seated accretionary complex, orgeny, tectonic development of the Japanese lslands, and tectonics of Asia were given, following metamorphic aspects of particular rock units.All of these results are arranged following the year published. Only abstracts of papers presented in 1988 and 1989 are shown in the last part of this report.