Radiolarian ages and geological structures of the shimanto belt in the kise-ouchiyama area of the eastern Kii peninsula, southwest japan. mem. fukui pref. dinosaur mus

The Shimanto Belt in the Kise-Ouchiyama area, the eastern Kii Peninsula of Southwest Japan, is mainly composed of broken and dismembered formations of the alternating beds of sandstone and shale with blocks of various lithologies, and is divided into the Kowatoge Complex on the north and the Complex A on the south. On the basis of stratigraphic relationships with lithologies and radiolarian ages, the oceanic plate stratigraphies can be reconstructed: chert, red siliceous shale, gray shale, greenish gray shale, black shale, alternating beds of sandstone and shale, and sandstone in ascending order. The radiolarian ages of black shale show Turonian (Late Cretaceous) for the Kowatoge Complex, and late Campanian (Late Cretaceous) for the Complex A. The Kowatoge Complex and the Complex A are sporadically distributed in some70kmfromwestto east. Mixed rock, which is characterized by chaotic mixtures of blocks of varied lithologies within sheared shale matrix, in the northern areas of the Complex A indicates dextral strike-slip deformation. Thus it is probable that the Coniacian to Santonian deposits are tectonically eroded by dextral strike-slip faults between the Kowatoge Complex and the Complex A.