木兰溪河口及邻近海域表层沉积物稀土元素组成与物源判别  

Rare earth element compositions and provenance implications:A case from sediments of the Mulanxi River Estuary and surrounding sea area

作　　者：苏妮[1] 毕磊[1] 郭玉龙[1] 杨守业[1] 

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092

出　　处：《海洋地质与第四纪地质》2018年第1期150-159,共10页Marine Geology & Quaternary Geology

基　　金：科技基础性工作专项"典型中小入海河流河口动力沉积地貌与环境本底数据调查"(2013FY112200);上海市优秀学科带头人计划(14XD1403600);国家自然科学基金项目"铀系同位素探究末次冰盛期以来东亚大陆边缘的风化沉积记录"(41506058);"山溪性入海河流物源变异及对气候事件的响应"(41776062)

摘　　要：福建木兰溪是我国东南沿海一条比较典型的潮控山地小河,从其流域风化剖面到河漫滩及邻近海域表层沉积物的粒度、化学风化程度及稀土元素(REEs)组成特征进行了研究。研究海区沉积物以黏土质粉砂为主,仅在木兰溪注入兴化湾口门处附近,沉积物较粗。沉积物REE的上陆壳(UCC)标准化模式具有相似性,轻重稀土元素分异不明显,稀土元素总量(ΣREE)及Eu异常的变化与平均粒径值、化学风化程度均有一定相关性。运用(La/Yb)N-ΣREE/Al图解较可靠判别了近海海域沉积物来源:(1)浙闽河流与长江细颗粒沉积物具有明显不同的REE组成;(2)兴化湾邻近海域主要受到内陆架泥质区沉积物物源的影响;(3)浙闽沿岸流携带的长江细颗粒物质影响可达泉州湾一带。由于泉州湾海域沉积物相对较粗,受石英"稀释作用"的影响,沉积物REE组成不均一性较强。The Mulanxi River in Fujian Province is a typical tide-dominated mountainous river in the southeast coast of China.The rare earth element（REEs）is adopted for provenance study and paleoenvironmental reconstruction in this paper.We investigated REE composition and provenance implications from both the weathering profile and the surface sediments of the Mulanxi River and its adjacent offshore areas.There the surface sediments are dominated by clayey silt with a very similar UCC normalized REE pattern and without obvious REE fractionation.Some REE index likeΣREE andδEu are related to the grain size and chemical weathering intensity.The（La/Yb）N-ΣREE/Al diagram is used to identify the sediment provenance in the study area.REE compositions from smaller rivers in Zhejiang and Fujian Provinces are significantly different from those of the Changjiang River.The sediments in the adjacent area of Xinghua Bay mainly come from the inner shelf mud of the East China Sea,and the fine suspended sediment of the Changjiang River carrying up by the Zhejiang and Fujian coastal current can be found in Quanzhou Bay and surrounding area.Since the sediments in the surrounding area of Quanzhou Bay are coarse,the REE composition shows strong spatial inhomogeneity due to the dilution by quartz.

关 键 词：沉积物 稀土元素 物源 沉积环境 木兰溪 

分 类 号：P595[天文地球—地球化学]