Major and trace elements of stream sediments from the lowermost Amazon River
Major and trace elements of stream sediments from the lowermost Amazon River
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DOI：
10.1016/s0009-2541(00)00191-1
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发表时间：
2000-07
期刊：
影响因子：
3.9
通讯作者：
H. Vital;K. Stattegger
中科院分区：
文献类型：
--
作者：
H. Vital;K. Stattegger
介绍了从亚马逊河最下游采集的河底沉积物的地球化学结果。对底泥中10种常量元素和38种次要元素进行了分析。泥质块状沉积物具有轻微富集铬、锰、Rb、锶、锆、铯、钡、氢等元素的趋势，表明这些元素在粉砂组分中的重要性。总体上，铜、锌、Rb、Cs、Ba、Sn与粘土矿物共生，Y、Zr、Hf、Th、U与重矿物共生。该地区处于强烈的化学风化环境中，导致沉积物成分发生强烈的变化。化学风化作用强烈地改变了原始沉积物的成分，并可根据其地球化学特征区别于物源过程。判别分析使检测沉积物特征中不太显著的差异成为可能，从而提高了组间区分的准确性。亚马逊河口和新谷口(XM)主要由其沉积物的结构成熟度来区分。Jari口(JM)的Co和Fe2O3含量最高。尽管亚马逊北枝(ANB)和亚马逊南枝(ASB)有相似之处，但ANB可以根据其更高的锶、P2O5和Na2O含量区分开来，ASB根据其更高的锌、MnO和CaO含量区分开来，Estreitos de Breves(EST)基于其更高的镍和铜丰度。P_2O_5、Fe、Mn含量较高与红土覆盖有关。
Geochemical results from river-bottom sediments taken from the lowermost Amazon River are presented. Bedload sediments were analyzed for 10 major and 38 minor elements. Mud bulk sediments exhibit a tendency to a slight enrichment in Cr, Mn, Rb, Sr, Zr, Cs, Ba and Hf, pointing to the importance of these elements in the silt fraction. Generally, Cu, Zn, Rb, Cs, Ba and Sn are clearly associated with clay minerals, while Y, Zr, Hf, Th and U are associated with heavy minerals. The location of this area in an intensive chemical weathering environment results in the strong modification of sediment composition. Chemical weathering processes strongly modify original sediment composition and can be recognized apart from provenance processes on the basis of their geochemical signature. Discriminant analysis makes the detection of less marked differences in sediment characteristics possible, thus, improving the accuracy of distinctions between groups. The Amazon Mouth and Xingu Mouth (XM) are discriminated principally by the textural maturity of their sediments. The Jari Mouth (JM) shows highest Co and Fe2O3contents. Despite similarities between the Amazon North Branch (ANB) and Amazon South Branch (ASB), the ANB can be differentiated on the basis of its higher Sr, P2O5, and Na2O contents, the ASB on the basis of its higher Zn, MnO, and CaO contents, and the Estreitos de Breves (EST) based on its higher abundance of Ni and Cu. Higher contents in P2O5, Fe, and Mn are related to laterite covers.