Abstract
The Kohachigagawa Complex is a Middle Jurassic accretionary complex in the Mino Belt in the Takayama area, Gifu Prefecture, central Japan. It is characterized by large amounts of oceanic rocks such as bedded chert, limestone and mafic volcanic rocks. The following two zones are identified in the Kohachigagawa Complex from lithology, mode of occurrence and deformation structure. Zone 1 is composed of slabs of oceanic rocks derived from Permian seamounts that are affected by intense cataclasis along a margin of each slab. Zone 2 is an imbricate stack of thrust sheets derived from component rocks of an oceanic plate stratigraphy including Permian to Early Jurassic ocean floor rocks. Toishi-type siliceous claystone and mafic volcanic rocks constitute the major or part of the decollements of the thrust sheets. Shear direction of the thrusts is top-to-the-east when a foliation trends east-northeast to northeast and dips steeply north, which is different from the shear direction of melange fabric and thrusts in the Late Jurassic to Early Cretaceous accretionary complex of the Mino Belt.
