南黄海南部陆区全新世沉积研究

The Study on Holocene Sedimentation in the Southern South Hnanghai Sea Coastal Land

研究区全新统不整合超覆于上更新亚统之上，自下而上由滨海相（局部含河口海湾相）、近岸浅海相（潮成沙体相）和潮滩相构成。全新统海侵层主要受控于晚更新世末ＳＥ→ＮＷ逐渐抬高的掀斜状古地形，表现出明显的水平相交，可归纳为四种层序类型。本文通过钻孔剖面分析对比，揭示了研究区垂向相序演替和水平相变的规律及其二者间的关系，恢复了全新世沉积演化过程。

The author discussed the Holocene sedimentary factes and its evolution, based mainly upon data of the eight drill-holes and also upon other several dozens of reference drill-holes, as well as the field investigation of the buried tidal sand bodies in the studied area for the first time. Characteristics of the sediments in the cores have been studied about their textures, structures,minerals and macrofossils. Radiometric dating 14C carried out for the importnt levels.It is non - marine facies of Pleistocene that underlay the sediment of Holocene with unconformity between them. The topography of the area at the end of Pleistocene inclined from northwest towards southeast which influenced the Holocene transgression obviously.The Holocene sedimentaly sequence can be divided into the lower transgressive and the upper regressive one, consisting of bcach facies(contains estuary- bay in some part of the area), nearshore neritic facies(tidal sand body facies)and tidal flat facies etc. It is obvious that factes change horizontally. In different environment appear different sedimentary sequences. The sequence can be classified into four types, which were discussed in detail in this peper. For all the four types, the best developed area is in the southeast part of the studied area, and the worst is in the northwest.The buried tidal sand bodies can be crassified into three types: Ⅰ )near-shore tidal sand bars ;Ⅱ ) tidal sand waves;Ⅲ) near - shore tidal sand ridges. They were formed and preserved successively along with the cycle of transgression and regression, and their distribution pattern was controlled by shift of the Changjiang river towards southeast during the Holocene.