MORPHOLOGY, SEISMIC RESPONSE AND EVOLUTION OF THE DEEP WATER CHANNEL SYSTEM, NORTHWEST SOUTH CHINA SEA

High-quality 2D seismic data are used in this paper in order to：a) Investigate the depositional architecture and the morphologic feature of the deepwater channel system, and b) Summarize the evolution of the seismic characteristics through the whole system. The deep water channel system extends from the east boundry of the Yinggehai basin, through the Qiongdongnan basin, and terminally eastward to the Shuangfeng basin. Based on the shape, erosion depth, width, the way of aggradations, and the internal fillings, whole system can be subdivided into four sedimentary units: central canyon-channel system, channel-lobe transition zone, channel-lobe system, and the margin of the channel-lobe system.

The development of the channel-levee, incised depth and width of the central channel system are primarily controlled by the styles of the continental slope, which have has five types, including: Progradation slope, slump slope, channelized slope, gentle gradient slope, and abrupt gradient slope. The canyon-channel system was highly extending on the gentle gradient slope with 14 km in width. The channel-lobe transition zone incises at canyon mouth, and then rapidly distributes out of the mouth for the weaker topography confine. Unconfined channel-lobe system developed in the Shuangfeng basin is characterized by lateral aggradational levees which is distributing to thousands meters. With no ability of erosion downward, the channel system terminated, forming extensive sheet sand.