RECENT VARIATION IN SEDIMENT GRAIN SIZE IN THE MUD AREA OF CHANGJIANG SUBAQUEOUS DELTA AND ITS INFLUENCE FACTORS

The subaqueous delta is a sink on the terrigenous clastic continental shelf. It contains tremendous information on environmental changes influenced by both the sediment supply and marine environmental dynamics. The core of SC09 was collected from the mud area of the subaqueous delta of the Changjiang River. Samples were taken for every 0.2cm of interval. Sediment grain sizes were measured by Mastersizer 2000 laser particle analyzer. Moreover, sediment grain-size sensitive populations were retrieved for analysis using the Empirical Mode Decomposition (EMD). The results show that the sensitive populations of grain-size are distinctly characterized by periodicity and a definite trend. The characteristics of fine grained sensitive populations were mainly relative to the changes in sediment supply from the Changjiang River, and the periodic changes and the trend of the coarse sensitive population reflect either the influence of extreme events, such as storm, or changes in the main course of Changjiang River.