雅鲁藏布江上游干支流稀土元素地球化学特征

Rare earth elements in the upper reaches of Yarlung Zangbo river

对雅鲁藏布江上游干支流水体及沉积物稀土元素含量、配分模式以及Ce、Eu特征元素参数进行研究,以探讨其地球化学特征及影响因素.结果表明,水体溶解态稀土元素含量平均值为19.28ng/L,沉积物稀土元素含量平均值为190.8mg/kg.水体稀土元素表现为重稀土元素富集(La_(N)/Yb_(N)<1),沉积物并表现为轻稀土富集(La_(N)/Yb_(N)>1);受岩石风化作用的影响水体Ce为负异常,沉积物Ce为无异常和弱负异常;受水岩相互作用对稀土元素在水-沉积物系统中迁移转化得影响,水体Eu表现为正异常,沉积物Eu表现为负异常.由于源岩类型不同导致的风化过程的差异,河源段与河流段稀土元素表现出明显的空间异质性.

The Contents and distribution patterns of rare earth elements and characteristic parameters of Ce and Eu in water and sediments of the upper reaches of the Yarlung Zangbo River were studied to explore its geochemical characteristics and influencing factors.The results showed that the average content of dissolved rare earth elements in water was 19.28ng/L,and the average content of rare earth elements in sediments was 190.8mg/kg.The rare earth elements in water are rich in heavy rare earth elements(LaN/YbN<1),while sediments with enrichment of light rare earth elements(LaN/YbN>1).Affected by rock weathering,Ce in water is a negative anomaly,or Ce in sediment is no anomaly and weak negative anomaly.Under the influence of water-rock interaction on the migration and transformation of rare earth elements in the water-sediment system,Eu in water shows a positive anomaly,and Eu in sediment shows a negative anomaly.Due to the difference in weathering process caused by different source rock types,the rare earth elements in the source and river sections show obvious spatial heterogeneity.