腾格里沙漠沙丘沉积物粒度特征及其空间差异

沉积物粒度特征对于研究物源、衡量搬运能量具有重要意义。分析了腾格里沙漠45个沙丘顶部样品的粒度特征，并计算了30 a输沙势。结果表明：（1）沙丘沙以细沙（71%）和中沙（20%）为主，平均粒径2.38 Φ，分选系数0.40 Φ；平均粒径与分选系数、偏度呈良好的线性关系。（2）分选为“极好”和“好”的样品整体分布在沙漠中部和西南部，前者概率累计曲线趋于近对称、中等峰态，为二段式，后者趋于正偏、中等或尖窄峰态，为三段式；而沙漠边缘分选较差，概率累计曲线为多段式。（3）盛行起沙风为西北风。西北和东北部属中风能环境，风况属单峰型和复杂型；南部和东南部分别属低、中风能环境，均双峰型风况。研究区沙丘沙源应以下伏河湖相沉积物就地起沙为主。沙漠边缘河湖相沉积物应该为中部区沙丘沙提供了物源，西南部沙丘沙可能源自石羊河下游的冲洪积物，风力分选作用较长，边缘沙丘沙则应来源于该区河湖相沉积物就地起沙，风力分选不充分。粒度参数空间分布特征与沙丘类型和规模之间存在一定的耦合关系。

Grain size characteristics of dune sands and spatial variation in the Tengger Desert

Sediment grain size parameters are of great significance for studying material sources and measuring the energy size. The grain size characteristics of 45 surface sand samples from the top of the dunes in the Tengger Desert were measured， and the Drift Potential of four weather stations in the past 30 years was calculated. The results show that： （1） Samples are mainly composed of fine （71%） and medium sands （20%）， with main grain size of 2.38 Φ and sorting of 0.40 Φ. There are good linear relationships between grain size and sorting， grain size and skewness. （2） The very well and well-sorted samples are entirely distributed in the middle and southwest of the desert， the former tends to be nearly symmetrical and medium-kurtosis， and the probability cumulative curve is composed of two-distinctive populations， while the latter tends to be positive skewness， medium or leptokurtosis， and the probability cumulative curve is composed of three-distinctive populations. However， the sorting of desert edge is inconsistent， and the probability cumulative curve is composed of multi-different populations. （3） The direction of prevailing sand-driving wind in the study area is northwest wind. The northwest and northeast parts of the desert were characterized by intermediate wind energy environment， with the unimodal and complex wind direction. The southern and southeastern parts of the desert belong to low and intermediate wind energy environment respectively， both of which are bimodal wind direction. The main sources of dunes in this area should be local detritus act of the underlying fluvial and lacustrine sediments. The fluvial and lacustrine sediments at the edge of the desert provide sources for the dune sands in the central region， the dune sands in the southwestern part may have originated from alluvial-lacustrine deposits in the lower reaches of Shiyang River， and the wind sorting effect is long， while the dune sands at the edge of the desert should be derived from local detritus act of the alluvial and lacustrine sediments， and the wind sorting effect is insufficient. There is a certain relationship between the spatial distribution characteristics of grain size parameters and dune type and size.