Analysis of major and trace elements by INAA to predict the thousands year old sediment deposition environment in the Meghna river delta
Analysis of major and trace elements by INAA to predict the thousands year old sediment deposition environment in the Meghna river delta
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DOI：
10.1007/s10967-009-0373-3
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发表时间：
2010-02
影响因子：
1.6
通讯作者：
H. Anawar;M. Freitas
中科院分区：
文献类型：
--
作者：
H. Anawar;M. Freitas
对不同层位沉积物中的常量、微量和稀土元素进行了测定，确定了组成矿物对梅格纳河三角洲元素分布和沉积环境的控制作用。相对于 PAAS（太古代平均页岩）值，沉积物的地球化学成分富集 SiO2、Ca、Mg 和 Ba，贫化 Al、Fe、Ti、Mn 和 Sr。 X 射线衍射和元素分析表明沉积物中主要存在石英、云母、长石、绿泥石、角闪石和粘土矿物。极低的微量元素含量表明更新世-全新世沉积物沉积期间含氧条件更为普遍，反映了生物地球化学反应引起的大规模化学风化。轻稀土元素的富集和La/Yb比值反映了梅格纳河三角洲地壳物质强烈的硅酸盐风化作用和较高的沉积物沉积速率。
Major, trace and rare earth elements have been measured in sediments of different layers to determine the controls of constituent minerals on the distribution of elements and sediment deposition environment in the Meghna river delta. The geochemical composition of sediments was enriched in SiO2, Ca, Mg and Ba and depleted in Al, Fe, Ti, Mn, and Sr relative to PAAS (Post-Archaen Average Shale) value. The X-ray diffraction and elemental analyses demonstrate the dominant presence of quartz, micas, feldspar, chlorite, amphibole and clay minerals in sediments. The very low contents of trace elements suggest that the oxic condition was more prevalent during sediment deposition of Pleistocene-Holocene period and reflect the massive chemical weathering by biogeochemical reactions. The enrichment of light rare earth elements and La/Yb ratio reflect the intense silicate weathering of crustal materials and the high sediment depositional rate in the Meghna river delta.