抄録
The Akima Formation of the Neogene system consists of seven members and mainly of mud flow beds. The Aima-gawa Valley area is adjacent to the region of Akima Formation. In this valley there are about one hundred sheets of lava flows intercalated in mud flows. The writers named newly these beds Aima-gawa Formation of which geological characters are as follows. 1) The Aima-gawa Formation mainly consists of tuff breccia beds, lava flows and several andesite bodies, and of the following stratigraphic succession. Kennomine lava, tuff breccia Member Omine lava, tuff breccia Member Tsunoochi lava, tuff breccia Member Odaira lava, tuff breccia Member Yakehoda tuff breccia Member Aima-gawa Formation Itahana Formation, Itahana or Yoshii Formation (Basements) 2) The andesite bodies which are contained in the Aima-gawa Formation distribute at Jujo, Tsunoochi, Odaira and Omine. 3) The Aima-gawa and Akima Formations are contemporaneous heterotopic sediments. The basements of Itahana and or Yoshii (?) Formations are recognized at several sites around the Odaira and Jujo andesite bodies. The fossils from the basements are foraminifera, mollusca and plants.
