North Yellow Sea Surface Sediment Grain Size Distribution Characteristics Of Its Indication Of Depositional Environment

Grain size of the 1140 surface sediment samples were analyzed in order f to probe into the relationship between the characteristics of grain size distribution and the sediment source or sedimentary dynamic conditions in the North Yellow Sea.The results indicate that the surface sediments in the study area can be divided into five types including mud , silt,sandy silt ,silty sand and sand,some of the samples contain gravels. Sediments with gravels mainly distribute near Changshan Islands, off Dalian Bay and adjacent area southeast. Sandy sediments dominate east of 123.3°E and near Changshan Islands.Silt is mostly located southwest of the study area and off Dalian Bay. Clay content is lower in study area. The area with more than 30% of clay content is confined southwestern locality,while area with more than 16% of clay content extends to north and northeast. Besides, the clay content is also more than 16% from Dalian Bay to Guanlu Island. The study area can be divided into five sediment environmental zones according to Folk and Pejrup's sediment classification methods and factor analysis to the sediment grain size, three of which are controlled by the environmental hydrodynamics and the others effected by the sediment sources. The Yellow Sea Warm Current restricts eastward transport of the fine-grade matter brought by the Shandong Peninsula coastal current. The main factor controlling the grain size characters is the tide in the eastern part of the study area and is the Shandong Peninsula coastal current in the western part. The grain size distribution of the fine sediments in the western study area is asymmetrical, and it is effected by the Shandong Peninsula coastal current, the Yellow Sea Warm Current and the tide.