中文摘要：

通过对黄河晋陕峡谷的深入调查研究,在延长永和县河段发现了典型的全新世晚期洪水滞流沉积剖面。在野外考察中,对沉积物的宏观特征和沉积环境及其分布特征进行观察,并进行了系统采样。在实验室对沉积物样品进行了粒度成分、磁化率、烧失量、CaCO3含量等测定。通过综合分析论证,表明黄河中游晋陕峡谷全新世晚期洪水滞流沉积物以粉砂为主,细砂含量次之,粘粒含量很少,分选性好,磁化率很低。其沉积学分类为细砂质粉砂,是黄河洪水悬移质泥沙在高水位滞流环境下的沉积物。将其与典型的全新世风成黄土和古土壤进行对比,可知其粒度成分比黄土和古土壤更粗,粒级分布更为集中。此外,将其与延河郭家川全新世洪水滞流沉积物对比,发现其粒度频率分布基本相似。该研究结果对于揭示黄河中游洪水水文泥沙特性及其历史演变具有重要意义。

英文摘要：

Field investigation was carried out along the Shanxi—Shaanxi Gorges in the middle reaches of the Yellow River. Typical flood slackwater deposit （SWD） of the late Holocene was identified at the Fotangcun site in the reach of Yonghe county. Sediment samples were taken after detailed observation of the texture and structure of the SWD profiles. Samples from the Guojiachuan site in the lower reach gorges of the Yanhe River,from the Holocene loess—soil at the Baishui loess tableland were also taken for a comparative study. Grain-size distribution,magnetic susceptibility,loss-on-ignition and CaCO3 content were measured in the laboratory. The results show that the flood slackwater deposit of the Yellow River consist of sandy silt which were deposited from the suspended sediment in the floodwater. Therefore they were well sorted during the deposition.The flood slackwater deposit from the Yanhe River have the similar grain-size distribution to the Yellow River. However,the loess and palaeosol are much finner than the slackwater deposit and they have very high magnetic susceptibility. This indicates that the SWD of the Yellow River are fresh sediment with little weathering and pedogenic alteration. This study is of great significance to establish a long-time scale hydrological data for flood control and hydraulic engineering in the middle reaches of the Yellow River.