长江三角洲地区晚新生代地质与环境研究进展述评

REVIEWS ON THE RESSEARCH OF LATE CENOZOIC GEOLOGY AND ENVIRONMENT OF THE YANGTZE RIVER DELTA AREA

长江是我国最长的河流和世界最主要的大河之一,长江三角洲地区则是我国人口最为密集和经济最为发达的地区之一。因此,研究长江三角洲地区晚新生代地质与环境的特征与变化,特别是长江河口地区的河谷变迁与三角洲发育,对于该地区的国计民生,具有十分重要的意义。长江三角洲地区晚新生代地质与环境的科学调查研究,已经走过了整整的一个世纪。随着经济的发展和科技的进步,长江三角洲地区晚新生代地质与环境的研究也取得了重大的进展。本文从现代三角洲发育、末次盛冰期长江河谷的深切与充填作用及冰后期地层的沉积相变化,埋藏硬土层的分布、特征、成因及其古土壤学性质,三角洲地区晚第四纪时期的海侵地层层序与新近纪及早、中第四纪地层及其沉积环境,以及从三角洲钻孔的碎屑锆石、独居石年龄谱及沉积物成分和地球化学组成随时间的变化来推论长江贯通三峡的时间等方面所取得的进展和所存在的问题,按照研究时间的大体顺序和地层的新老次序进行了较详细的综述和简要评论。最后根据自己的认识和判断,概括了长江三角洲地区近一个世纪来研究工作所取得的进展和所存在的问题,并在此基础上提出了今后进一步工作的几点建议,希望能引起广大同仁及有关部门的注意,以期达到抛砖引玉的目的。

The Yangtze River is the longest river in China and one of the most main rivers in the world. The Yangtze River delta area is one of the most densely populated and economically developed areas in China.Therefore,studying characteristics and changes of Late Cenozoic geology and environment of the area is of very important significance for national welfare and the people's livelihood there. This kind of studies has had a whole century of history. With the development of economy and the progress of science and technology,some major progress has been made in this studies. In this paper we reviewed progress made on basis of data of such aspects as the modern development of the Yangtze River delta,incision and filling of the Yangtze River valleys during the latest pleniglacial age,changes of sedimentary facies during the post-glacial period,the distribution,characteristics and origin of buried hard earth layers,Late Quaternary transgressive sequences and Neogene and Early-Middle Quaternary stratigraphic units and sedimentary environments in the Yangtze River delta area, sedimentary compositions and geochemical analyses of delta sediments,and age spectrums of detrital zircon and monazite from borehole samples. Among the progress is the time of the Yangtze River breaking through the Three Gorges as an obstacle. At the same time some open questions were also pointed out in this paper. Then according to the reviews,we put forward several suggestions for the coming research to call researchers 'attention to produce the effect of throwing away a brick in order to get a gem.