渤海湾西岸的第一道贝壳堤的年代学研究及1千年来的岸线变化

CHRONOLOGY OF THE CHENIER Ⅰ AND SHORELINE CHANGES SINCE THE LAST 1KA,ON WESTERN COAST OF BOHAI BAY

取自堤下部的 1 4 C平均校正年龄表明 ,渤海湾西岸沿现代海岸线展布的第一道贝壳堤 ( 堤 )的初始年龄约在 90 0～ 70 0 cal BP/AD10 5 0～ 12 5 0 ,堤的发育延续至 18、19世纪。以往 1 4 C数据因取样位置不当 (一般取自堤的中部 ) ,不能用于支持文献中关于该堤起始时间的判断 ;但是这批数据连同文献中获自岸外残存贝壳碎屑堆积层的数据 ,暗示隋、唐贝壳堤存在的可能性。近 1千年来该地区贝壳堤的发育反映了海岸线的重大变化。

A set of average calibration ages,obtained from the lower part of cheniers indicate that Chenier Ⅰ along the west shoreline of Bohai Bay began to form in about 700～900 cal BP(1050-1250AD),and continued to develop until 18～19 centuries.This is about 100～300 years earlier than the estimate of its initial time from the previous literature.The existing 14 C dates can not be used to support and/or oppose such an estimate because those dates were obtained from the middle part of the chenier.However,such dates with a 14 C date coming from a narrow,eroded shelly bed about 2～3 km off the present day shoreline,suggest that all these belong to the Sui/Tang Chenier,which no longer existed after about 11 century.