LATE TERTIARY SEQUENCE STRATIGRAPHY AND SEA LEVEL CHANGES IN YINGGEHAIQIONGDONGNAN BASIN

Thirteen depositional sequences are presented based on the analyses of well logs and seismic data in Late Tertiary in Yinggehai Qiongdongnan basin, the northern part of South China Sea.The ages of 13 depositional sequence boundaries are dated by bio datum planes (planktonic foraminifera)as 1 9, 2 2, 2 8, 3 4, 5 1, 6 0, 10 2, 12 6, 15 2, 19 6, 21 0, 23 7, 25 5 and 30 0 Ma respectively.The cycles of relative sea level changes are discussed systematically according to the depositional systems and sedimentary facies.The highest stand of sea level developed in Middle and Lower Pliocene,approximately in the interval between the N 19 and the lower part of N 21 planktonic foraminiferal zones. Another high stand of sea level happened in Middle Miocene, roughly from the N 9 to the N 12 planktonic foraminiferal zones.The cycles of relative sea level changes can be correlated with that of Haq et al.(1987).