长江三角洲地区晚第四纪地层及潜在环境问题  

LATE QUATERNARY STRATIGRAPHICAL FRAMEWORK AND POTENTIAL ENVIRONMENTAL PROBLEMS IN THE YANGTZE DELTA AREA

作　　者：李从先[1] 范代读[1] 张家强[1] 

机构地区：[1]同济大学教育部海洋地质开放实验室,上海200092

出　　处：《海洋地质与第四纪地质》2000年第3期1-7,共7页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金资助项目! ( 4 99760 16)

摘　　要：根据钻孔的沉积相序将长江三角洲分为三角洲主体、三角洲南翼和北翼等 3个基本的地层分区 ,鉴于两翼前缘和后缘的相序具有很大差异 ,因而两翼均划分出前缘和后缘 2个亚区。地层结构的不同决定了与沉积层有关的潜在环境问题和灾害的分布 ,三角洲南翼和北翼的后缘为地面沉降发育区和潜在发育区 ,北翼的前缘为地下海水入侵的潜在发育区 ,三角洲主体是污染江水的潜在渗滤区 。Based on the analysis of drilling cores,the Yangtze Delta region can be subdivided into three basic areas by late Quaternary stratigraphical framework.They are main delta,southern and northern flanks.In both flanks there exists stiff mud as a basement of the postglacial transgressive sedimentary cycle(PTSC),which belongs to the paleosol in genesis,exposed for a long term.The PTSC thickness is varied from 3 5m to 25 28m and increased eastward.The postglacial thansgressive sedimentary cycle basically consists of muddy deposits of littoral,neritic and littoral facies in the front zone of the southern flank,and is mainly composed of sandy deposits of that in the northern flank.The PTSC in the back zone of both flanks consists of marsh lacustrine muddy deposits.There is no stiff mud in the postglacial transgressive sedimentary cycle with thickness of 60 90m in the mail delta area.The PTSC has erosional surface at the bottom and is composed of river channel sand,floodplain estuary sandy and silty clay,estuary bay soft mud and deltaic sandy clay and sand.Muddy unit thins and then punches out westward,and is completely eroded at some places,so that deltaic and river channel sandy units are superposed on each other.The upper surface of paleosol and the bottom erosional surface constitute lower boundary of the postglacial transgressive sedimentary cycle.The incised valley and associated floodplain at its both banks can be recognized in the Yangtze Delta region during last glaciation maximum,which coincides with present main delta and its both flanks respectively.These paleogeomorphological units and stratigraphical framework in the Yangtze Delta have succeeded during various transgressive cycles of Quaternary. There are some hazards and potential environmental phenomen

关 键 词：地层构架 环境问题 晚第四纪 长江三角洲 

分 类 号：P736.21[天文地球—海洋地质]