Abstract:

To better understand the transport path and deposition center of Pearl River originated sediment on the shelf off western Guangdong coast, the grain size trend of 1 515 surface sediments were analyzed by using Gao-Collins method and the modern sedimentation rate of 8 core samples was measured based on ²¹⁰Pb method. The results show that outside the river mouth, the main part of muddy sediment provided by Pearl River was confined to inner shelf with water depth less than 50 m, due to the combined effects of two oppositely flowing current: the coastal current and the South China Sea warm current. A modern sedimentation rate of about 0.1 cm/a on western Guangdong muddy shelf can be maintained by Pearl River originated sediment. Two modern sedimentation centers exist, they are Chuanshan Islands-Hailing Island muddy zone and the muddy area lay east of Qiongzhou Strait, controlled by island blocking and a counter-clockwise mesoscale eddy, respectively. As the source and the way of transport of coarse and fine sediment may be different, the grain size trend result may mainly reflect the transport trend of coarse sediment but not the migrating direction of fine sediment.

Key words: Pearl River, source to sink, modern sedimentation rate, grain size trend, western Guangdong, northeastern Hainan