半干旱区沼泽沉积物粒度特征及环境意义

以半干旱区无尾河下游漫流区的向海沼泽为研究对象 ,通过对沼泽垂直剖面的精细采样 ,将放射性核素精确计年与沉积物粒度研究相结合 ,进行高分辨率剖析。结果表明 ,沼泽垂直剖面颗粒的基本构成以粉砂和砂为主 ,沉积环境变化频繁。流水作用以河流为主 ,并有受洪水影响的痕迹。部分层位的风成作用明显是那个时代干旱的标志。沙丘风蚀与风的搬运作用 ,局部改变了沼泽区域上沉积物的组成 ,使之粗化 ,是沼泽退化的诱因之一。向海沼泽沉积物颗粒表现出来的韵律性准周期变化特征 ,揭示了流域气候“干—湿”的周期性演替。

Characteristics and Environmental Significance of the Granularity of Swampy Sediment in Semi-arid Areas

Currently, the research on the granularity of swampy sediment is relatively feeble. In this paper, a case study on the characteristics and environmental significance of the granularity of swampy sediment is carried out in the swampy area at the lower reaches of Huolin River located in a semi-arid area. By combining the research on the radionuclide timing and the sediment granularity, the analyzed results of the sediment profiles in high resolving power show that the basic composition of the swampy profiles is dominated by silt and sand, and the change of the sedimentary environment is frequent. In the fluviatile action, river action is dominant and flood action is subsidiary. Aeolian sedimentation is obvious in some strata, which reflects the arid sedimentary environment. In the study area, the composition of the swampy sediment is partially changed by wind erosion and aeolian sedimentation, which is one of the causes resulting in the degeneration of swamps. The periodical climate change in the watershed is revealed by the characteristics of the swampy sediment granularity in Xianghai Region.