Surface Sediment Distribution and Sedimentary Environment on the East China Continental Shelf

The distribution and grain-size characteristics of 209 surface sediment samples on the East China Continental Shelf were studied for understanding the provenance and hydrodynamic conditions closely related to the fine sediment distribution pattern in the study area.The surface sediment samples were classified into seven types in grain size: sand,silty sand,muddy sand,sandy silt,sandy mud,silt and mud,plus gravel,occasionally.The surface sediment samples mainly belong ed to coarse sandy sediment,which were mainly located in north central region of the East China Sea,shoal waters along northern coast of Jiangsu province,and northern region of the Northern Yellow Sea.The sandy sediments were characterized by a mean size of 2~4Φ,poor in sorting with sorting coefficient 2,strongly positive skewness ranging from 2 to 2.80,and wide to very wide kurtosis ranging from 1.60 to 3.50.The fine sediments were mainly located in the stretch from Zhejiang coast waters to the Yangtze estuary,old Yellow River subaqueous delta off northern coast of Jiangsu province,central region of the South Yellow Sea,western part of the North Yellow Sea,and shallow waters off the Yellow River mouth in the Bohai Sea.The fine sediments were characterized by a mean size of 6~7Φ,a poor to relatively poor in sorting with sorting coefficient of 1~2.5,a negative to nearly symmetric skewness ranging from-1.50 to 0.33,and a very wide kurtosis with kurtosis coefficient 2.75.The effects of large rivers input and ocean current systems on the fine sediment distribution patterns were primarily analyzed,and sediment provenance and transport route of rivers discharged sediment were deduced.