GRAIN SIZE DISTRIBUTION PATTERN OF SURFACE SEDIMENTS IN THE NORTHERN YANTAI COASTAL WATERS AND ITS BEARING ON HYDRODYNAMIC ENVIRONMENT

Based on the 56 surface sediment samples collected from the northern Yantai coastal waters, the grain size distribution pattern of the sediments was analyzed. The sedimentary dynamic environment of the study area was defined by the Pejrup triangle diagram, and the transport trend of the sediments revealed by the Gao-Collins grain size trend analysis method. On this basis, the characteristics of the sedimentary dynamic environment of the study area were discussed. Results show that the grain size distribution of the study area is characterized by a pattern with coarse sediments in the center surrounded by fine deposits in the east and west; and thus the study area can be divided into seven sedimentary dynamic environments areas: AⅢ, BⅢ, BⅣ, CⅢ, CⅣ, DⅢ and DⅣ. Dynamically, strong environment occurs in the center, weak environments on both sides, or strong near shore and weak far shore; Two depositional centers are discovered in the open sea areas of the eastern and western parts of the study area, and the sediment sources are rather diverse; The movement and distribution of surface sediments in the area are basically dependent upon hydrodynamic conditions, influenced by sediment sources. And the sedimentary dynamic environment is jointly determined by tidal currents, coastal currents and sediment sources.