【作者】 劳金秀；

【导师】 杨祝良； 王锡魁；

【作者基本信息】 吉林大学 ， 第四纪地质学， 2009， 硕士

【摘要】 长江三角洲是世界著名三角洲之一,也是我国人口最密集、经济最发达的地区之一。大河三角洲地区以其巨大的河流物质供应和复杂的水动力条件,成为全球变化研究的典型区域。长江三角洲在末次盛冰期以来形成演变,是在全球大幅度海退与海侵,以及全新世以来海面波动的驱动下发育起来的,是海陆相互作用的产物,在历史时期以来又受到强烈的人类活动的影响,并且势必会在将来继续受到全球气候—海面变化,以及流域内自然与人为机制的交互作用而发生一系列与社会生产生活密切相关的重大变化。因此,进行长江三角洲全新世沉积特征及其古环境演变研究,探讨其变化的规律,具有重大的理论意义和现实意义。本文的研究目的是对江都-镇江高桥地区进行钻孔地层沉积特征及岩相古地理环境演变进行研究。对古河谷横断面多钻孔进行系统对比,力图重塑区域岩相古地理环境变迁过程,并进一步探讨环境演变机制。在研究中,主要是通过研究区36个钻孔的岩心沉积特征及研究区基坑沉积特征,结合¹⁴C测年数据及前人研究成果,确定研究区全新统底界,并对研究区进行全新统地层划分。通过沉积物的物质成分、结构、原生沉积构造、沉积产状及其生物组合等则划分沉积相。并绘制全新统沉积等厚图,结合沉积特征进行岩相古地理分析,绘制全新世早期岩相古地理图和全新世中期岩相古地理图。以反映全新世岩相古地理环境演化。研究结果表明,研究区沉积物的沉积特征自下而上总体上表现为由粗变细的正粒序,局部由于水量增大出现局部小的由细—粗—细的反粒序。研究区主要为河流相、牛轭湖相、泛滥平原相。全新世以来长江河道曾经两次由北向南迁移,由于河床的摆动,使得研究区的岩相古地理演变是伴随着河床的摆动而改变。更多还原

【Abstract】 Yangtze River Delta is one of the word-famous Delta,also is the most densely populated of China and one of the most developed regions of economy.Studying the characteristics of Holocene sediments and evolution of paleo-environment of Yangtze River Delta,examining the changes in the law has great theoretical and practical significance,on the whole,the study of the sedimentary characteristics and the sedimentary characteristics of Yangtze River Delta made a lot of results.However,most of the micro-study and the macro trends more researchof a single drill have been hole depth,but not a combination of both research,especially lack for the ancient fiver valley cross-section with more drilling of systematic research.However,as a result of the riverbed swing and the horizontal phase change,and the stratigraphic record is different between the adjacent drill.If the density of the drill does not have enough,it is difficult to accurately compare the form of the restoration of the ancient river valley.Relying on the ’Yangzhong City,Jiangdu County,Jianbi Town and Taizhou City of regional geological survey of Jiangsu 1:5 million’ project,the report studyed on sedimentary characteristics and the environmental change of lithofacies palaeogeography in Jiangdu-Zhenjiang Gaoqiao area. Combining wiht the previous data,the Holocene sediment stratigraphy of study area is divided into Rudong group and Yujian group.This study is 24 dating data,and References Institute of Geological Survey of Jiangsu Province（2003） 1:25 million regional geological survey of the research results,through acquisition the carbonization of plant debris deposition on the first layer of hard clay in the study area Its ¹⁴C dating is 12988±310a.In accordance with the Stratigraphic Guide of China（2001）,combine the characteristics of the region,as defined in the bottom of Holocene age about 12ka.The first layer of hard clay roof is the end of the Holocene in deposition characteristics. Integrated previous information,the drilling sediment stratigraphy in Holocene is divided into Rudong group and Yujian group in this article.Based on the large number of drill data achieved by previous researches and ours,we analysis the sedimentary characteristics of Jiangdu and Gaoqiao area in Zhenjiang。The main types of sedimentary structures in the study area include horizontal bedding, parallel bedding,current bedding,homogeneous bedding,draining structure,wavy bedding,rhythmic bedding,and linsen bedding and so on.According to the material composition,structure,connate deposit structure,depositional occurrence and biological combination,the sedimentary facies in this area will be divided into fluvial facies,oxbow lake-facies and flood plains facies。The fluvial facies further into the river bed subfacies and diara（sand dams） subfacies.Based on the sedimentary characteristics and dating data of Holocene,the lithofacies palaeogeography environment is divided into the early-Holocene,mid-Holocene and Late-Holocene。We draft the isopach of Holocene,the lithofacies paleogeographic map of early-Holocene and mid-Holocen。And then we describe the evolution of the lithofacies paleogeographic environment in Holocene。更多还原