黄土高原黄土的平均化学成分与地壳克拉克值的类比

COMPARISON OF AVERAGE CHEMICAL COMPOSITION OF LOESS IN LOESS PLATEAU WITH CLARK VALUES OF CRUST

笔者对黄土高原的马兰黄土进行了系统地采样，共采集样品１４７块（最后组合成１００块样品进行分析），对每个样品都分析了５４种元素，并用质量加权法计算了黄土各元素的丰度值。结果表明，黄土高原各地黄土的化学成分彼此十分类似，具有良好的均匀性特征。并且，黄土的平均化学成分十分接近现在使用的地壳克拉克值。因此，笔者认为，可以用黄土的平均化学成分来代表大陆上部地壳的平均化学组成。从理论上说，风成黄土的物源区很大，又是天然高度均匀混合，因而比前人的方法更合理，更具有代表性，更接近上部陆壳的真实情况。并且认为，这是研究地壳克拉克值的一条新途径，也是今后研究黄土地球化学的一个新的方向。

Authors systematically collected 147 samples(at last constituting 100 samples for analysis) of Malan Loess in Loess Plateau and 54 elements were analysed for each sample. Abundance of each element was calculated by means of weighted average method.The results showed that chemical compositions of loess were very similar to each other in all parts of Loess Plateau with a good characteristic of homogenity. Moreover, the average chemical compositions of las were very close to Clark values of crust, which are used at Present. Therefore,the average chemical compositions of loess may be used to represent average chemical constituents of continental upper crust. From theoritical point of view, typical colian loess has a very large area of material sources and was also mixed homogeneously. Consequently, using it to calculate Clark values of upper crust should be more reasonable, more representative and more substantial than previous methods. Therefore, it could be a new way for investigation of Clark values of crust and a new field of loess geochemistry study in future.