抄録
So-called `high-grade' blocks of `non-eclogitic' metabasaltic rocks from the Franciscan Complex were petrologically investigated. High Ti content in brown clinoamphibole and the presence of clinopyroxene-rich veins with possibly pseudomorph after orthopyroxene suggest the block underwent nearly granulite-facies metamorphism with migmatitic partial melting. Those rocks might represent fragments of `metamorphic sole' formed during infant stage subduction with a `hot' geothermal gradient, following intra-oceanic subduction initiation.