论文部分内容阅读
On the basis of the 14C dating data, lithological characters biological and chemical compositions and so on, the relict sediment of the East China Sea shelf is divided into two types of genesis -regression and transgression, with four sedimention periodes in this paper.The upper relict sediment layer is the sandy sediment of the transgressive bottom layer in Postglacial period. Its sediment age becomes younger and younger from east to west. The direction of its age variation is in accord with the transgressive direction, showing that the sandy sediment is the product of transgression in Post-glacial period. The age of the lower relict sediment layer is over 15,000 a. BP. The main variation trend appears older in the west but younger in the east, agreeing with the regressive direction of glacial epoch at the end of Epipleistocene.
On the basis of the 14C dating data, lithological characters biological and chemical compositions and so on, the relict sediment of the East China Sea shelf is divided into two types of genesis-regression and transgression, with four sedimention periodes in this paper. Upper relict sediment layer is the sandy sediment of the transgressive bottom layer in Postglacial period. Its sediment age becomes younger and younger from east to west. The direction of its age variation is in accord with the transgressive direction, showing that the sandy sediment is the product of transgression in Post-glacial period. The age of the lower relict sediment layer is over 15,000 a. BP. The main variation trend appears older in the west but younger in the east, agreeing with the regressive direction of glacial epoch at the end of Epipleistocene.