郭玉龙, 杨守业, 苏妮, 印萍, 王中波. 中国东南入海河流沉积物的稀土元素地球化学特征[J]. 海洋地质与第四纪地质, 2018, 38(1): 139-149. DOI: 10.16562/j.cnki.0256-1492.2018.01.014
引用本文: 郭玉龙, 杨守业, 苏妮, 印萍, 王中波. 中国东南入海河流沉积物的稀土元素地球化学特征[J]. 海洋地质与第四纪地质, 2018, 38(1): 139-149. DOI: 10.16562/j.cnki.0256-1492.2018.01.014
GUO Yulong, YANG Shouye, SU Ni, YIN Ping, WANG Zhongbo. Rare earth element geochemistry of the sediments from small rivers draining southeast China[J]. Marine Geology & Quaternary Geology, 2018, 38(1): 139-149. DOI: 10.16562/j.cnki.0256-1492.2018.01.014
Citation: GUO Yulong, YANG Shouye, SU Ni, YIN Ping, WANG Zhongbo. Rare earth element geochemistry of the sediments from small rivers draining southeast China[J]. Marine Geology & Quaternary Geology, 2018, 38(1): 139-149. DOI: 10.16562/j.cnki.0256-1492.2018.01.014

中国东南入海河流沉积物的稀土元素地球化学特征

Rare earth element geochemistry of the sediments from small rivers draining southeast China

  • 摘要: 系统采集了浙闽三条中小河流的代表性表层沉积物和悬浮物样品,用1N盐酸淋滤样品,研究稀土元素(REE)在酸溶及酸不溶相态中的组成特征。浙闽河流沉积物酸溶组分中的REE在总REE中的占比可达32%~82%,其中Fe-Mn氧化物和黏土矿物吸附态是细粒沉积物酸溶组分REE的主要赋存形式。浙闽河流沉积物酸溶组分的REE组成反映其遭受化学风化的信息;酸不溶组分主要由硅酸盐造岩矿物和稳定副矿物组成,尤其是锆石对REE组成有重要贡献。酸不溶相REE组成揭示,当地流域风化物质与潮流作用带入的长江源细颗粒是浙闽河口沉积物的主要来源。REE在风化及水动力分选过程中会发生分异,使得沉积物全岩组成不直接继承其源岩的REE组成特征,运用于物源判别时候需要慎重。中国东南河流沉积物显示Gd异常,这不是人类活动引起的Gd输入所致,而只反映中国东部物质的组成特征。

     

    Abstract: Representative suspended and floodplain sediment samples were systematically collected from three small rivers in Zhejiang and Fujian provinces. Two chemical phases (leachates and residues) were separated by 1N HCl leaching and the leachates account for 32%~82% of the total REE concentration. The absorption on Mn-Fe (hydro)oxides and clay minerals are the main hosts of acid-leachable REEs. The REE compositions of the leachates can potentially indicate the whole weathering history of the sediments to some extent. Silicate minerals and stable heavy minerals like zircon are important hosts of residual REEs, and the residual fractions are reliable for the indication of sediment provenance. The weathering products of river basins and Changjiang-derived sediments pumped by strong tide into the estuaries are the main sources of these rivers sediments. REE fractionation is demonstrated during extreme chemical weathering and hydrodynamic sorting processes, and thus it should be cautious to use the bulk REE compositions of these river sediments to indicate the sediment provenance. Slight positive Gd anomalies occur both in the leachates and residues, which do not indicate the presence of anthropogenic Gd, but reflect the geochemical compositions of the materials in Eastern China.

     

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