新生代末期の火成活動の問題点
(特集「新生代末期の火成活動」(第29回総会シンポジウム))
1976 年 30 巻 2 号 p. 106-109
詳細
1976 年 30 巻 2 号 p. 106-109
In order to get the whole phenomenon of the igneous activity at Late Cenozoic age, the volume estimation of the volcanic materials formed in each stage of Late Cenozoic age carried out by the auther. Volcanic activity of the Middle Miocene (Nishikurosawa and onnagawa stage) is represented by the bimodal volcanism of basalt-rhyolite assiciation. On the other hand, acid volcanism such as dacite ignimbrite succeeded from Funakawa to Kitaura stage, mainly in the Backborn range of Tohoku. It became again violent at the end of the Shibikawa stage. Volcanic materials derived from the Quaternary volcanism are in large amount and show the unique episode in volcanic activity of Cenozoic age. It is a noteworthy that about 80% of the Quaternary volcanic materials was derived from andesite magma.
