Cover photograph : Orbicular granite of the Mt. Sanage, Aichi Prefecture An orbicular granite occurs in the Mt. Sanage of Toyota City, and designated as National Monument since 1931. The granite belongs to the most fractionated phase of the late Cretaceous ilmenite-series biotite granite of the Ryoke Youndder type, and its orbicular textures are caused by variation of the grain size and amounts of K-feldspar, quartz and biotite. Unlike the famed orbicular granite in the Mineyama, Mt. Tsukuba, of similar tectonic setting, no cordierite is observed in this locality. |