The Crust and Upper Mantle of the East China Sea (Seismic Tomography and Gravity Models)

Gravity and seismic tomography models of the tectonosphere, which allow greater detailing and refining of the structure of the crust and subcrustal mantle in the region are considered. In the East China Sea, the crust is considerably deconsolidated; this deconsolidation has been found to be continued within the subcrustal mantle down to a depth of 40-45 km. A wide NW-trending transform-fault-related pull-apart zone has been identified at the western boundary of the Pacific Plate. In the eastern East China Sea areas, the lower layer of the Philippine oceanic lithosphere is underthrust beneath the Ryukyu Arc with further underthrusting under a viscous subcrustal layer of the continental shelf. In the central sea areas, the oceanic lithosphere is upthrust on the continental marginal lithosphere. Evidence of a central-type structure, which is likely of plume origin, has been detected in the subasthenospheric mantle layer at the western boundary of the Philippine Sea plate, which is the middle fragment of the Ryukyu Arc.