R8: Metamorphic rocks and tectonics

[R8-15] Metamorphic condition of the metamorphic rocks of Chikujo Town, Fukuoka Pref. and Otsushima Island, Yamaguchi Pref. , in southwest Japan

*ZEJIN LU¹, Masaaki Owada¹, Naoki Shibata¹ (1. Yamaguchi Univ. Sci)

Keywords:HT metamorphic rocks, P-T path, Geothermal gradient

The Suo Belt metamorphic rocks, the Triassic HP type, are exposed in southwest Japan. Recently, LP metamorphic rocks associated with Cretaceous granitoids have been reported in the Suo Belt. Otsushima, Yamaguchi and Chikujo town, Fukuoka are underlain by low-pressure metamorphic rocks originated from the Suo belt, and show a clockwise P-T path. In Otsuhima, the geothermal gradient of structurally upper level is 80-100℃/km and that of lower level is 40-50℃/km.