POSTGLACIAL TRANSGRESSIVE SEDIMENTARY RECORDS OF MUDDY SEDIMENTARY AREAS IN THE NORTH OF THE SOUTH YELLOW SEA

Results from the sedimentary analysis of three cores from the north muddy area of the South Yellow Sea have shown that the postglacial transgressive sediments consist of the following units: 1) the bottom coarse-grained sedimentary layer, that is the transgressive lag deposit, comprising shell fragments or sandy silt rich in shell fragments; 2) the intermediate normal grading sedimentary layer, changing upwards from sandy silt to sand-silt-clay to clayey silt, and 3) the upper fine-grained layer, that is silty clay rich in water moisture and with the average grain size of about 8. The relatively deep species of foraminifers and ostracods mainly appear in the fine-grained sediments, but euryhaline littoral, shallow water and cold water species of foraminifers and continental, euryhaline and brackish water and shallow water species of ostracods are only found in the normal grading layer. Generally, the species decrease in number from bottom to up, indicating that the normal grading layer was deposited during the postglacial sea level rising period and the fine grains were formed during the high sea level time in Holocene. The stable accumulation of the fine-grained sediments above the Holocene maximum flooding surface in the north of the South Yellow Sea have probably indicated the formation of the modern Yellow Sea circulation pattern following the appearance of the Warm Current in the Sea since the middle time of Holocene.