Styles of mesoscale brittle deformations associated with the Miocene folding of the Taishu Group, Tsushima, between the Japan Sea and East China Sea backarc basins

The Taishu Group is a folded, Eocene–Lower Miocene, thick sedimentary package exposed widely on Tsushima Island between the Japan Sea and East China Sea. This location makes strata important to understand tectonics paleo-environments in Far East, but timing of folding controversial. We studied styles brittle deformations strata. It was found that flextural-slip folds were dominant. Mesoscale faults classified into two groups: NE–SW trending reverse NW–SE strike-slip faults. Members both groups showed movements largely perpendicular fold axes. latter group consisted sinistral dextral Accordingly, we interpreted they transfer activated during folding. Consequently, mesoscale flexural-slip evidence map-scale plane strain NE-trending There few transpressional group. inconsistent with transpression hypothesis for explaining simultaneous opening. Another which are regarded as an onshore part Taiwan-Shinji belt suggested by mining geologists be consistent contemporaneous this deformation. On other hand, dolerite dikes sills involved Therefore, conclude began late Early Miocene time climaxed ore mineralization at around 15 Ma. suggest easternmost manifestation compressional regime Yellow early Middle compression brought about arrival Philippine plate initiate buoyant subduction under Kyushu.