Origin and provenance of the surficial sediments in the subenvironments of the East China Sea

Grain size and clay mineral composition are analyzed for the surface sediments in various depositional units of the East China Sea including its outer shelf and slope, and the Okinawa Trough.Upon the basis, the origin and provenance of the sediments are discussed.Results show that the grain size of the sediments becomes finer gradually from the outer continental shelf, slope, to the Okinawa Trough.The sediments in the outer continental shelf are dominated by beach sands or breaker zone deposits formed during the deglacial transgression of late Pleistocene, and belong to the so-called "relict sediment", while the sediment on the western slope of the Okinawa Trough is characterized by gravity flow deposits, indicating a transportation pattern from the outer continental shelf to the Trough.Suspended deposits predominate the bottom fine sediment of the Okinawa Trough, having the characteristics of bathyal deposits.They are mainly from the rivers of Taiwan and Mainland China, such as the Changjiang and Minjiang Rivers.Provenance study reveals that the fine materials from Taiwan is mainly transported by Kuroshio Current, and the fine sediments from Mainland China are mainly transported by various transportation mechanisms, such as the"near-bottom lateral transportation"and"storage in winter and transporting in summer."