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对汉江上游郧县段一级阶地上典型古洪水滞流沉积物、古土壤和黄土3种不同沉积物的宏观特征、粒度成分、理化性质、微观形态及地球化学元素进行了综合分析对比。结果表明,研究剖面中的古洪水滞流沉积物呈灰黄色(2.5YR7/2),与上下相邻地层往往呈突变关系且界线清晰;粒度组成总体较粗,粉砂质细砂土,分选较好;磁化率稍高于马兰黄土,但显著低于古土壤;烧失量平均值低于黄土和古土壤;石英颗粒表面分布有水下环境机械相撞形成的V形坑;元素的含量及UCC标准化曲线均与黄土和古土壤差异明显。与渭河谷地相比,汉江上游谷地古洪水滞流沉积物具有粒度组成偏粗、分选性稍差的特点。该研究成果对汉江上游谷地古洪水滞流沉积物的鉴别和古洪水水文参数的重建具有重要意义。
The macroscopic characteristics, grain size composition, physicochemical properties, microscopic morphology and geochemical elements of three typical sediments, paleosol and loess sediments of the first flood terrace in the upper reaches of the Hanjiang River were analyzed and compared. The results show that the paleo-flood sediment in the study section is greyish-yellow (2.5YR7 / 2), and often has a sudden change of relationship with the adjacent upper and lower strata and the boundaries are clear. The grain size composition is generally coarse, silty fine sand, The magnetic susceptibility is slightly higher than that of Malan loess, but significantly lower than that of paleosol; the average loss on ignition is lower than that of loess and paleosol; the V-shaped pit formed by the mechanical collision of underwater environment is distributed on the surface of quartz particle; The content and UCC standardized curve are obviously different from loess and paleosol. Compared with the Weihe Valley, the sediment of the ancient flood stagnation in the upper reaches of the Hanjiang River has the features of coarse grain size and slightly poor sorting. The results of this study are of great significance to the identification of stagnant sediments of paleo-floods in the upper reaches of the Hanjiang River and the reconstruction of paleo-hydrological parameters.