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Mineralogy and geochemistry of modern Yellow River sediments: Implications for weathering and provenance

机译:现代黄河沉积物的矿物学和地球化学:风化和物质的影响

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摘要

This study illustrates the textural, mineralogical and geochemical signatures of sediments from the upper Yellow River. Sediments of major tributaries have also been examined to study the influence of provenance, weathering intensity, and hydraulic sorting on the spatial compositional variability of sediments. Similarly to floodplain sediments, riverbed deposits are strongly depleted in MgO and Na2O, and enriched in CaO and Si2O relative to the upper-continental-crust standard. The pattern of rare earth elements (REE) indicates LREE enrichment and negative Eu anomaly (Eu/Eu*=0.54-0.68). Low CIA (Chemical Index of Alteration) values indicate that the sediments from the trunk-river channel, floodplain, and major tributaries have not experienced intense chemical weathering in arid to semi-arid climatic conditions. The distribution of chemical elements shows a significant increase of Zr and Hf with coarsening of grain-size, whereas Rb, Ni, and V are associated with finer sediment fractions supplied by adjacent dune fields and tributaries. The Al/Si ratio (a proxy for grain size) correlates positively with CIA, Fe2O3, MgO, and K2O, but not with Na2O, reflecting grain-size control. Clay mineral assemblages in the upper Yellow River and in tributaries draining the Loess Plateau (e.g., Qingshui and Zuli Rivers) are dominated by illite and chlorite, whereas the abundance of smectite characterizes the middle reaches of the Yellow River and the Ten tributaries draining the Ordos Plateau.
机译:该研究说明了来自上黄河沉积物的纹理,矿物学和地球化学特征。还研究了主要支流沉积物,研究了出处,风化强度和液压排序对沉积物的空间组成变异性的影响。与洪泛区沉积物同样,河床矿床在MgO和Na2O中耗尽,并相对于大陆地壳标准富含CAO和SI2O。稀土元素(REE)的图案表明LREE富集和负欧盟异常(EU / EU * = 0.54-0.68)。低中CIA(改变化学指标)值表明,中继河道,洪泛区和主要支流的沉积物在干旱地对半干旱气候条件下没有经历过强化化学风化。化学元素的分布显示Zr和HF的显着增加,晶粒尺寸粗化,而Rb,Ni和V与相邻的沙丘场和支流提供的更精细的沉积物部分相关。 Al / Si比(晶粒尺寸的代理)与CIA,Fe2O3,MgO和K2O相比正相关,但不与Na2O相反,反映晶粒尺寸控制。粘土矿物组合在上黄河中和支流中排出黄土高原(如清水和Zuli Rivers)的矿石占据了伊利米特和亚氯矿石,而蒙脱石的丰富性是黄河中游的,而且十个支流排放了鄂尔多斯的十个支流高原。

著录项

  • 来源
    《Chemical geology》 |2018年第2018期|共11页
  • 作者单位

    Lanzhou Univ Coll Earth &

    Environm Sci Key Lab Western Chinas Environm Syst Minist Educ Lanzhou 730000 Gansu Peoples R China;

    Lanzhou Univ Coll Earth &

    Environm Sci Key Lab Western Chinas Environm Syst Minist Educ Lanzhou 730000 Gansu Peoples R China;

    Univ Milano Bicocca Dept Earth &

    Environm Sci I-20126 Milan Italy;

    Lanzhou Univ Coll Earth &

    Environm Sci Key Lab Western Chinas Environm Syst Minist Educ Lanzhou 730000 Gansu Peoples R China;

    Lanzhou Univ Coll Earth &

    Environm Sci Key Lab Western Chinas Environm Syst Minist Educ Lanzhou 730000 Gansu Peoples R China;

    Lanzhou Univ Coll Earth &

    Environm Sci Key Lab Western Chinas Environm Syst Minist Educ Lanzhou 730000 Gansu Peoples R China;

  • 收录信息
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地球化学;
  • 关键词

    Yellow River; Provenance analysis; Sedimentary geochemistry; Clay mineral assemblages; Chemical weathering; Arid climate;

    机译:黄河;源分析;沉积地球化学;粘土矿物组合;化学风化;干旱的气候;

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