曹娥江沉积物黏土矿物与磁性特征及其指示意义  

Magnetic properties and clay mineralogy of the surface sediments of Cao'e River basin and implications

作　　者：何姗姗 师育新[1] 戴雪荣[1] 许锐 刘朝[1] 

机构地区：[1]华东师范大学地理科学学院,上海200241

出　　处：《海洋地质与第四纪地质》2018年第1期108-117,共10页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金项目"钱塘江流域河流沉积物1.4nm黏土矿物及其物源示踪研究"(41371214)

摘　　要：曹娥江位于钱塘江河口区,建河口大闸前受钱塘江涌潮影响,沉积作用与物质来源较复杂,建闸后则改变了河流原有沉积作用与物质来源。采用XRD和环境磁学分析,对曹娥江流域表层物质中的黏土矿物组合和磁性特征进行了研究,并探讨了曹娥江干流沉积物来源。结果表明:表土与支流沉积物黏土矿物组合和磁性参数特征相似,1.4nm黏土矿物以蛭石和1.4nm过渡矿物为主,χ、SIRM、HIRM和χARM值较高。干流不同河段沉积物黏土矿物组合和磁性参数特征存在差异,上浦闸以上河段1.4nm黏土矿物以蛭石为主,4种磁性参数值较高,与表土、支流沉积物的值相近;新三江闸以下河段1.4nm黏土矿物以绿泥石为主,磁性参数值相对最低;上浦闸至新三江闸段1.4nm黏土矿物则以绿泥石+蛭石为主,磁性参数值介于前两者之间。物源分析结果显示,上浦闸以上河段干流沉积物来自于上游支流和流域表土,新三江闸以下河段干流沉积物主要为江外(长江口、杭州湾和钱塘江)物质,上浦闸至新三江闸段则兼有流域和江外两个区域物质,且江外物质对其影响更大。The Cao＇e River is located in the Qiantang River estuary.The sedimentation and provenance of the river were complicated under the effect of the Qiantang River tide before the estuary sluice was built in December 2008.XRD and environmental magnetism are adopted as means to study clay mineralogy of the surface sediments and their spatial distribution in this paper,with emphasis on the sources of clay minerals in the mainstream and the influence of estuary sluice on sedimentation after construction.Results show that the clay mineral assemblages in tributaries are rather similar to those in topsoil sediments,in which the 1.4 nm clay minerals are dominated by vermiculite and1.4 nm mixed layer clays.In the mainstream,however,the contents of 1.4 nm clay minerals vary at different river sections.For examples,vermiculite dominates the1.4 nm clay minerals in the upper reach before the Shangpu gate,chlorite in the lower reaches of the New Sanjiang gate,and two 1.4 nm clay minerals（chlorite and vermiculite）in the section between the Shangpu gate and the New Sanjiang gate.With regard to the magnetic properties of the sediments,they are similar among topsoil,tributaries and the upper reach sediments of the Shangpu gate.The magnetic properties of sediments＇ in the lower reaches of the New Sanjiang Gate is similar to that offshore.Magnetic properties of sediments between the Shangpu gate and New Sanjiang gate vary in between.The study of sediment source shows that the sediments of the mainstream above the Shangpu gate comes from tributaries and topsoils;sediments of the lower reaches of the New Sanjiang Gate from the Yangtze River,Hangzhou Bay and Qiantang River;and the sediments between the Shangpu gate and New Sanjiang gate from tributaries and topsoils with strong influence of materials from the outside of the River.

关 键 词：曹娥江流域 表层沉积物 黏土矿物 物源 河口大闸 

分 类 号：P512.2[天文地球—地质学] P619.231