中文摘要：

赣北鄱阳湖地区沙山南部近南北向的芙蓉-周溪断面上，分布由FZ-01、FZ-02～FZ-05和FZ-06～FZ-12三部分组成的下蜀土剖面，粒度分析结果表明：1）下蜀黄土砂粒组分自北往南变化为27.29%、1.94%～7.23%和0.45%～7.27%；粉砂组分质量分数大，且存在差异变化，分别为68.23%、81.71%～87.20%和66.9%～79.39%；黏土组分自北向南质量分数增加，变化为4.48%、8.46%～16.35%和18.13%～32.07%，总体表现为砂黄土-黄土-黏黄土等相态的逐渐过渡；2）粒度三组分、粒度参数散点图等均表现为从北而南的阶段性系统渐变特征；3）各种粒度参数与距长江的远近，均服从对数函数变化关系。这些特征初步揭示研究区的下蜀黄土是风成的，并可能与同样是风成堆积的沙山的形成存在某种联系，属于区域性风沙-风尘堆积体系。

英文摘要：

Xiashu loess is distributed over the southern dune in Poyang lake region,the north of Jiangxi province. The color of the loess becomes darker and darker from south to north, but the layer and sedimentology characters in different places are similar. It is homogeneous,unstratified and blocky in structure. Xiashu loess lies on the bedrock formed in different times and with different causes, or lies on the palaeo-landform which is formed from accumulation and suffered from serious erosion. Thick loess normally deposited in the front parts of mountains, while lesser loess on the peaks and steep slopes. On the whole, the thickness of the Xiashu loess reduces gradually from north to south. The granularity data of the section from Furong （located on the south bank of the Yangtze River） to Zhouxi （located on the shore of Poyang Lake） along a N-S direction shows that： 1） Sand grain component changes from north to south, and the concrete data are 27.29%, 1.94%～7.23%and 0.45%～7.27%. The silt component varies greatly, the data are 68.23%, 81.71%～87.20% and 66.9%～79.39%. The clay component increases gradually from north to south, the data are 4.48%, 8.46%～16.35% and 18.13%～32.07%. The overall performance is that the sedimentary facies of the Xiashu loess change from sandy loess to loess to clayey loess;2） Change characteristics of triangular chart of clay-silt-sand and granularity parameters scatter diagrams vary systematically from north to south; 3） All kinds of granularity parameters have involvement with the distance from the Yangtze river, which conform to logarithmic function. According to the index system and using the acquirable data, we consider that the Xiashu loess is an eolian deposit, it may have a certain relation with the formation of the sand dune in Poyang Lake region, belonging to regional sand-dus eolian deposition system.