Types of cenozoic sedimentary basins of the East Asia and Pacific Ocean junction area

Abstract

A rather wide class of structures has been distinguished in marginal basins. The marginal basins in the modern Pacific can be classified, based on the type of crust and their position relative to the structures of active continental margin. Sedimentary basins of the Philippine Sea, East China Sea, Yellow Sea and Bohai Sea comprise oceanic and transitional crust and form trenches and back-arc, inter-arc, forearc and intra-arc basins. Basins with continental crust consists of marginal-continental shelf and intracontinental basins. In the first-type basins the crust thickness ranges from 4.2 to 24 km. They are sea basins, rather deep, only partially filled with marine sediments with substantial volcaniclastics and lavas. Their basement is generally made up of volcanics. In inter- and intra-arc basins of the group, polymetallic sulphide ores have been found. Treches have favourable conditions for gas accumulation. The second type of basin was fonmed at the expense of rifting of continental crust with a thickness of 28–44 km. They are completely filled with alluvial deltaic and lacustrine sediments up to 11 km thick. Basins of this type are rich in oil and gas.