Based on distribution of Mesozoic in East China Sea and magmatic-tectonic events in the eastern Fujian and Zhejiang provinces

Kula-Pacific plate would have relatively strong subduction toward China's mainland during Jurassic-Early Cretaceous

thus East China Sea and the area to the south should be of fore-arc basin. During late Late Cretaceous-Eocene

volcanic island arc moved eastward and the East China Sea shelf basin was turned into a back-arc basin. The centers of fault subsidence were located in Changjiang and Oujiang sags in the western part of the shelf basin during Palaeocene

and they moved eastward during Eocene and consisted mainly of the Xihu sag in the eastern part of the shelf basin. East China Sea shelf basin was downwarped in Oligocene

due to the change of subduction direction of Pacific plate and the effect of Philippine Sea plate

and the center of depression was mainly located in the eastern part. Okinawa ocean trough and Ryukyu island arc were formed in late Miocene. During late Miocene (approx. 6 Ma)

Luzon island arc collided with China's mainland in Taiwan area

resulting in the emergence of Taiwan Island

and the formation of the present features of Taixi(or West Taiwan) basin.