武都黄土剖面稀土元素研究

A STUDY ON REE OF WUDU LOESS

武都剖面晚更新世以来黄土的稀土元素地球化学分析结果表明，轻重稀土元素之间具有比黄土高原其他地区较强烈的分异作用，而这种强烈的分异作用，与其较高的粘土矿物含量及其吸附作用相关；另一方面，武都稀土元素具有与其他地区黄土相似的稀土分布模式；反映沉积物来源的特征参数显示，武都黄土与黄土高原典型剖面十分一致，故具相同来源。武都黄土是黄土高原在西秦岭山地的外延。

REE geochemistry of Wudu loess since Late Pleistocene shows that the differentiation of LREE and HREE in Wudu area is stronger than that in the other areas of Huangtu Gaoyuan (Loess Plateau). The mean LREE / HREE ratios are 9.88 in Wudu loess, 6.18 in Lanzhou loess, and 7.5-8.2 in Luochuan loess. The total content of REE in Wudu loess is much higher than that in Lanzhou and Luochuan loess. This is not only related to the climatic envi ronment in Wudu area, but also related to the high content of clay minerals in Wudu loess. On the other hand, the REE distribution pattern of Wudu loess is similar to that in Lanzhou and Luochuan loess. The other parameters, such as Eu/Sm, Sm/Nd and Eu/Eu, indicate that Wudu loess has the same source as Luochuan and Lanzhou loess. This is also supported by the major and other trace elemental analyses. Therefore,Wudu loess is the extension of the Loess Plateau in Qingling Mountains. The loess was transported from the arid-semiarid Middle Asia by wind.