Cretaceous volcanic and plutonic rocks are widely distributed in the central part of Chugoku district，southwest Japan．The Cretaceous igneous rocks in and around Kisa-cho in northern Hiroshima Prefecture，are divided into the Kisa Volcanics，the Takada Rhyolites and granitoids．Takada Rholites，which erupted immediately following the Kisa Volcanics，is composed mainly of rhyolitic pyroclastic flow deposits．We called this volcano-plutonic complex in Kisacho，Futami Volcano-plutonic complex．
Two samples of plagioclase from the lapilli tuff of the Takada Rhyolites have Sr isotopic ratios of 0.70648 ± 2 and 0.70672 ± 1． Sr isotopic ratios of the host rocks of the plagioclases are not available．Initial Sr isotopic ratios of the
plagioclases differ from the andesite-dacite group，but are similar to those of granitoids of the Futami Volcano-plutonic complex．