Sedimentology, structural geology, and tectonics of the Shikoku subduction zone, southwestern Japan

摘要: The Shikoku subduction zone is developed along the Nankai Trough where Philippine plate underthrust beneath Asian plate. landward wall of consists horizontal parallel ridges and basins that trend northeastward. A Deep Sea Drilling Project site (Leg 31, 298) on flank deepest ridge penetrated 525 m beds in normal stratigraphic position 86 overturned (all Quaternary age), indicating an anticline. tight, anticline, which trends to Trough, has inter-limb angle 9°, axial surface inclined 9° 14° landward, a convergently fanning plane fracture cleavage. coarsening-upward turbidite sequence defines trench facies demonstrates direct accretion deposits from this environment. convergence rate estimated be 1 2 cm/yr, with strain about 10 −13 /sec. Tectonic consolidation reduced volume subducted accreted rocks at least one-third. Olistrostromes form as consequence fold evolution submarine environment can immediately underthrust, thereby developing structural fabric.