SEDIMENT SOURCE AND ITS BEARING ON MARINE SEDIMENTATION

The source of sediment is the key to understanding the land-sea interaction and sea level changes in the history. The Chinese marginal seas are bounded by a huge continent in the west and the trinity of trench, island arc and back-arc basin in the east. There exist two distinctive sources to supply sediments to the China Seas. One is the continent of China, which provides enormous sediments through rivers from the west to the east. The other one is island arcs. In addition to the sediments carried by short rivers from the islands, volcanic debris is significant. The sedimentary sequence in the backarc basin is characterized by the alternation of marine sediments and volcanic deposits. The sources of shelf sediments change with sea level fluctuation. During the glacial stage, allochthonous shelf sediments from the land dominated, while in the interglacial stage, autochthonous shelf sediments, which were from the erosion of relict deposits, moved from the continental edge to the inner shelf. The alternation of sediment sources is a critical factor in control over both the Quaternary depositional sequence and the distribution pattern of surficial sediments in the China Seas.