The Earth’s Crust and Upper Mantle of the East China Sea (Seimotomographic and Gravity Models)

Abstract

Gravity and seismic-tomography models of the tectonosphere detailing and specifying the structure of the crust and upper mantle of the East China Sea are considered. Crust of this region has considerably lower density extending into the subcrustal layer to a depth of 40–45 km. A transform-fault-related wide pull-apart zone of NW strike is identified on the western edge of the Pacific plate. In east regions of the East China Sea the lower layer of the Philippine oceanic lithosphere is underthrust beneath the Ryukyu arc and further ‒ beneath the viscous subcrustal layer of the continental shelf. In the western regions, the oceanic lithosphere is thrusted over the continental margin crust. Evidence of the central type structure of presumably plume origin is found in the layer below the asthenosphere on the western edge of the Philippine plate (a middle fragment of the Ryukyu arc).