SEDIMENT GRAIN SIZE DISTRIBUTION PATTERN AND TRANSPORTATION TREND IN THE XUANDE WATER, SOUTH CHINA SEA

Grain size analysis and parameter calculation have been carried out for 151 surface sediments collected from the Xuande Waters in the South China Sea. Results show that the surface sediments of the area are made of 8 types of sediments dominated by sand and gravel. Silt and clay contents are relatively small. Factor and Cluster analysis of grain size parameters is used to discriminate different depositional environments. The study area can be further divided into four subareas, The subareaⅠis mainly located in the middle of study area, the subarea Ⅱnear the reefs, the subarea Ⅲ located in the inner Xuande Atoll, and the subarea Ⅳ located in lateral edges of the reef atoll. Grain size trend analysis suggests that the sediment transport pattern is consistent with the hydrodynamic conditions of the study area, and a sediment depositional area is formed in the water next to the Tri Ton island.