Metamorphism of high–Mg garnet and kyanite-bearing garnet amphibolites from the Tonaru metagabbro mass, Sambagawa metamorphic belt, central Shikoku, Japan

Abstract

Two generations of garnet have been identified from the kyanite garnet-amphibolite which occurs in the Tonaru metagabbro mass, Besshi district, central Shikoku, Japan. Kyanite-garnet amphibolites from the western parts of the Tonaru metagabbro mass are composed mainly of amphibole, zoisite, kyanite and garnet. Garnets are pyrope-rich in composition, increasing X_Prp (0.36–0.53) and decreasing X_Alm (0.44–0.32) from the core to the rim. Network-like micro-veins occur throughout the garnets which are filled by Fe-rich garnet. Micro-veins have a composition of almandine (X_Alm 0.43–0.53), and pyrope (X_Prp 0.24–0.39) with minor spessartine (X_Sps 0.02–0.07) components.