Middle Jurassic radiolarians from chert clasts within conglomerates of the Itsuki Formation of the Itoshiro Subgroup (Tetori Group) in the Taniyamadani Valley, Fukui Prefecture, central Japan

This paper reports Middle Jurassic radiolarians observed in etched surfaces of chert clasts within conglomerates of the Itsuki Formation of the Itoshiro Subgroup (Tetori Group) in the Taniyamadani Valley, Fukui Prefecture, central Japan. This is the first report of Middle Jurassic chert clasts within the Tetori Group. Middle Jurassic cherts were included in late Middle Jurassic and younger accretionary complexes in East Asia on the basis of previous studies. This study indicates that late Middle or younger accretionary complexes had been exposed and denuded in the provenance of the Tetori Group by the depositional time of the Itsuki Formation