四国中央部，西石原地域における御荷鉾緑色岩類の地質構造

Geological structures of the Mikabu greenstones and northern margin of the Chichibu
Terrain are studied in the Nishi-ishihara Area, Central Shikoku. The Mikabu greenstones are not
considered to occur in the area between Nishi-ishihara and Kamiyakawa in Central Shikoku,
because of the existence of the Nishi-ishihara thrust. This study, however, clarified that the
Mikabu greenstones composed of tuff and tuff breccia occur in a narrow zone there. Therefore,
the Mikabu greenstones are considered to expose continuously from Nishi-ishihara to west of
Kamidoi.
The Mikabu greenstones are intercalated in the Jurassic accretionary complex, and form an
antiform. The antiform of the Nishi-ishihara area can be traced to the Nanokawa area in Middle
West Shikoku, and also affects the Mikabu greenstones near Mt. Zohshi-yama. Jurassic
complex under the Mikabu greenstones lies in the axial part of the antiform. The complexes of
the northern and southern limbs have the same lithologic characters with each other. The
Kamiyakawa-Ikegawa Tectonic Line, which runs along the antiformal hinge, is not a fault
separating the Sanbagawa Metamorphic Terrain from the Northern Chichibu Terrain.