Precise U-series dating of coral reefs from the South China Sea and the high sea level during the Holocene

Coral reefs formed along the southern coast of Hainan Island are one of the most developed Holocene fringing reefs in China. We present new precise ²³⁰Th ages of coral reefs collected from the Shuiweiling section in the southern coast of the Hainan Island, Dengloujiao in the southwest of the Leizhou Peninsula, and the Chenhang Island and Jinyin Island of the Xisha (Paracel) Islands in the South China Sea. Using the high-precision U-series dates and stratigraphic evidence, the timing and character of the sea-level variations of the middle-Holocene in study region are examined. The results show that a flourishing period of coral reef flats in the South China Sea and along its northern coasts appeared in ca. 6800 to 5800 a BP, which is 650 to 950 years earlier than the previous ¹⁴C dates (6150-4850 a). The sea level relative to the southern coasts of South China Sea was 3 to 4 m or more higher than that of the present during this period.