Three types of gamets from the metamorphic xenoliths within the Takatsukiyama granitic mass in the Shimanto belt, southwest Japan

The Takatsukiyama granitic mass，intruded into the Cretaceous Shimanto belt，is a typical S-type granitic intrusion of middle Miocene age，and contains several types of xenoliths of regional metamorphic roks such as blastomylonite，blastomylonitic gneiss，gneiss and migmatitic gneiss．These metamorphic rocks often contain gamets，which are classified into three types，i．e．，types A，B and C．Type A gamet shows a normal zoning and occurs only in blastomylonite．Type B garnet has no distinct chemical zoning occurring in blastomylonite，blastomylonitic gneiss and gneiss．Type C garnet shows a distinct reverse zoning and it occurs in migmatitic gneiss．Elementalcolor map（CMP）technique of EPMA well reveals the chemical zoning of the garmets．