The Motai-Matsugataira Belt (MMB) in the eastern margin of the northeastern Japan arc comprises Paleozoic metamorphic complexes. The high-P Yamagami metamorphic rocks in the belt are subdivided into the high-grade Yamagami I and low-grade Yamagami II units. The Yamagami I metamorphic rocks consist mainly of pelitic schist, epidote amphibolite, and garnet amphibolite. The occurrence of paragonite in rutile and the chemistry of amphiboles indicate that the Yamagami I metamorphic rocks underwent

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... e highest-grade metamorphism in the MMB. Phengite K-Ar ages of the pelitic schists and amphibolitesindicateexhumation during to Ma. These petrological and geochronological results for the Yamagami metamorphic rocks indicate that part of the MMB is probably an extension of the Renge Belt of southwestern Japan.