长江下游南京-镇江河段河漫滩粒度特征  

Grain-size Characteristics of Overbank Sediments in the Lower Reaches of the Changjiang River and Its Environmental Implication

作　　者：张凌华[1,2] 张振克[1,2] 符跃鑫[1,2] 陈影影[1,2] 蒋大亮 张志荣[1,2] 蒋松柳[1,2] 

机构地区：[1]南京大学地理与海洋科学学院 [2]南京大学海岸与海岛开发教育部重点实验室,江苏南京210023

出　　处：《地理科学》2015年第9期1183-1190,共8页Scientia Geographica Sinica

基　　金：国家自然科学基金项目(41371024);国家理科人才培养基地项目(J1103408)资助

摘　　要：分析长江南京-镇江河段3个现代河漫滩沉积孔上部100 cm的粒度特征,探讨宁镇河段现代河漫滩的沉积环境。结果表明:GB孔、ZR孔和ZH孔沉积水动力较小,沉积物颗粒较细,均以粉砂为主;ZR孔的砂含量最多、沉积粒径最大、粒径和砂含量由底层向表层增加;ZH孔分选系数呈明显的阶段性特征。研究认为:河流比降、河势、分汊河床演变以及滩面植被是影响宁镇河段河漫滩粒度特征的重要因素。River floodplains are constructional features of the fluvial landscape, and the overbank deposition on floodplain represent the geomorphological and hydrological conditions of a certain river. This article analyzed grain-size characteristics of three 100 centimeters long overbank cores sampled at Nanjing-Zhenjiang Reach in the downstream of the Changjiang River and its environment implication. The results indicate that the grain size results of overbank cores are not only controlled by the floods but also genesisly related to sedimentary environment. Both the floods intensity and the depositional environment of the overbank should be considered during the research of the overbank sediments feature and its influence factors. Along the Nanjing-Zhenjiang Reach, the grain size analysis of the three cores indicated the hydrodynamics on the overbank during the floods was weak and the whole cores were mainly composed of the fine sediments. The relatively stable part of the sediments was clay, varying between 11.43%-17.65%. Among the three cores, the ZR Core was located at the highest depositional hydrodynamics condition, the coarser grain size was obvious and the highest sand content was 66.73%. The vertical distributions of the grain size parameters of the GB Core were varied in the same way, and it was also the same in the ZR Core, furthermore, the sand contents increased upward in the ZR Core.The sorting of the ZH core had two obvious stages, the upper part with the much better sorting than the lower part of the core, which was different from the vertical distributions of the other parameters. Along the Nanjing-Zhenjiang Reach, the outcrop of the overbank sediments was composed of the thin layers of fine and coarser silts, corresponding with the alternation of weak and strong hydrodynamics during the flooding on the overbank. The obvious fine sand layers of the outcrop indicated the strongest period of flooding. The other factors influenced the grain size features included the following factors： the river channel g

关 键 词：河漫滩 粒度特征 长江下游 沉积环境 

分 类 号：K903[历史地理—人文地理学]