四国の上部白亜系，和泉層群，外和泉層群，四万十累層群の放散虫群集と対比

Six radiolarian assemblage zones are proposed, based on the stratigraphic and correlative works of the local assemblages that are distinguished and described from the Upper Cretaceous Izumi and Sotoizumi Groups and Shimanto Supergroup in Shikoku. The ages are evidenced based on the matching with the macrofossils, especially ammonites and inoceramus. The newly established assemblage zones are the Pseudodictyomitra vestalensis (Uppermost Albian to Cenomanian), Pseudodictyomitra nakasekoi (Turonian to Lower Coniacian), Stichomitra manifesta (Coniacian), Stichomitra compsa (Lower to Middle Campanian), Amphipyndax pseudoconulus (Upper Campanian), and Amphipyndax tylotus (Uppermost Campanian to Maastrichitian) Assemblage Zones. In the Izumi Group that are characterized by eastward younging turbidite sequences, lithostratigraphic horizons are marked by acid tuffs as key-beds, and the ages are discussed by the occurrence of ammonites and inoceramus. In the Sotoizumi Group, the ages of the formations are discussed by co-occurrence of ammonites and inoceramus. In the Shimanto Supergroup, lithostratigraphy of each accretional prysms is verified based on the oceanic plate stratigraphy as the chert-clastic units.