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为了探讨“巫山黄土”的成因,对剖面样品进行了稀土元素含量、稀土分布模式和稀土特征值计算分析.结果表明:“巫山黄土”稀土元素特征与现代河流沉积物差别明显,而与北方黄土及长江中下游的下蜀土却基本一致.稀土分布模式与典型风尘沉积物相似,物源判别函数得到的物源指数(PI)均与风积黄土的最为接近,显示其风积成因的特点.“巫山黄土”稀土元素平均含量216.39×10-6高于地壳平均值178.0×10-6和两块中国黄土标样平均值178.22×10-6,但与长江中下游镇江下蜀土样品的平均值207.7×10-6比较接近.样品的轻稀土较富集,重稀土略有淋失,轻重稀土比值为8.62,Eu呈较明显的负异常,Ce异常不明显.表明“巫山黄土”风尘沉积后经历了较北方黄土更为强烈的风化作用,其形成环境与下蜀土比较接近.
In order to explore the causes of the “Wushan loess”, the rare earth elements, rare earth distribution patterns and rare earth eigenvalues of the samples were calculated and analyzed.The results show that the characteristics of rare earth elements in Wushan loess and modern river sediments are obviously different, But similar to the loess in the northern loess and the middle and lower reaches of the Yangtze River.The distribution pattern of rare earth is similar to typical aeolian sediments, and the provenance index (PI) obtained by the discriminant function of origin is the closest to that of aeolian loess, indicating that the wind The average content of rare earth elements in Wushan loess is 216.39 × 10-6 which is higher than the crustal average of 178.0 × 10-6 and the average of two loess samples in China is 178.22 × 10-6, The average value of soil samples of Shuxu soil in Shijiazhuang is 207.7 × 10-6, and the light rare earths are enriched, the heavy rare earths are slightly leached, the ratio of light and heavy rare earths is 8.62, the Eu shows obvious negative anomalies, and the Ce anomaly is insignificant. It shows that “Wushan loess” experienced stronger weathering than the northern loess after its deposition, and its formation environment is relatively close to that of Xiashu.