The Deposition Characteristics And The Evolution Of The Lithofacies Palaeogeography Environment Of Holocene Of Jiangdu And Gaoqiao Area In Zhenjiang

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。...