论文部分内容阅读
本文在地貌、第四纪地质野外调查和３３个钻孔资料的基础上，运用粒度、碎屑重矿物、微体古生物和１４Ｃ年代测定等方法探讨江平沿岸沙坝－泻湖体系的沉积相序和沉积环境演变过程。沙坝－泻湖发育在一片起伏不平的基岩侵蚀面上，其沉积相序自下而上为：基岩侵蚀面→河床→、河漫滩相→河口湾、近岸浅海相→滨外沙坝、半封闭泻湖相→风成沙丘、封闭充填泻湖沼泽相。本区的沙坝泻湖属于海退型。作者初步认为本区沙坝可分为新、老２期，老沙坝大约形成于６７００～３６００ａＢ．Ｐ，新沙坝大约形成于２３００～１０００ａＢ．Ｐ。
Based on the geomorphology, Quaternary geology field survey and 33 borehole data, sedimentary facies sequences of sand bar-lagoon system along the Yangtze River are explored by means of particle size, heavy mineral detritus, microfacies paleontology and 14C dating. Depositional environment evolution. Sand dam - lagoon developed in a rugged bedrock erosion surface, the sedimentary facies sequence from bottom to top: bedrock erosion surface → riverbed → river floodplain → estuary → coastal shallow seas → offshore sand bar, Semi-closed lagoon → wind into sand dunes, closed filled lagoon swamp phase. Shaba Lagoon in this area belongs to the sea retreat type. The authors initially believe that this area can be divided into new and old sand bars 2, the old sand dam formed about 6700 ~ 3600aB. P, Xinsha dam formed about 2300 ~ 1000aB. P.