长江口水下三角洲沉积物粒度组成及其在减沙背景下的响应

发布时间：2018-04-06 04:04

本文选题：粒度　切入点：减砂　出处：《地质通报》2016年10期

【摘要】：近年来长江口水下三角洲对入海泥沙减少的响应问题越来越受到关注。通过分析长江水下三角洲百年沉积速率的分布特征及位于水下三角洲泥质沉积区不同位置4个浅孔的粒度、~(210)Pb和~(137)Cs数据,探讨其对流域入海水沙变化及水动力变化的响应。研究结果显示,1954年后长江口北支萎缩是导致CDZS10孔所在区域沉积物粒度较其他3孔明显粗的主要原因。而CDZS10孔沉积物上粗下细则是由20世纪80年代三峡蓄水后长江入海泥沙显著下降、海洋动力明显增强引起的。另外,北支萎缩及三峡水库调蓄作用导致泥质区南移,并向杭州湾和嵊泗列岛延伸发展。
[Abstract]:In recent years, more and more attention has been paid to the response of underwater deltas in the Changjiang Estuary to the reduction of sediment into the sea.Based on the analysis of the distribution characteristics of the century-old deposition rate in the Yangtze River underwater delta and the data of granularity of four shallow pores located at different positions in the muddy sedimentary area of the Yangtze River Delta, the data of Pb210Pb and 137Cs are analyzed, and their responses to the changes of sediment and hydrodynamics in the basin are discussed.The results show that the atrophy of the northern branch of the Changjiang Estuary after 1954 is the main reason for the coarse grain size of the sediment in the area of the CDZS10 pore.However, the upper and lower depth of the sediment in the CDZS10 pore is caused by the obvious decrease of sediment in the Yangtze River after the three Gorges impoundment in the 1980s, and the obvious enhancement of the marine dynamics.In addition, the atrophy of the northern branch and the regulation and storage of the three Gorges Reservoir lead to the southward movement of the muddy area and its extension to the Hangzhou Bay and Shengsi Islands.
【作者单位】：上海市地质调查研究院;华东师范大学河口海岸国家重点实验室;
【基金】：中国地质调查局项目(编号:GZH201200506) 国土资源部项目(编号:201211009)
【分类号】：P736.21

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