塔克拉玛干沙漠腹地纵向沙垅表面沙物质粒度特征

本文对塔克拉玛干沙漠腹地纵向沙垅表面沙粒、丘间地沙粒进行了粒度分析。结果表明，沙垅以极细沙为主，平均粒径３．０６Φ，沙粒从沙垅迎风侧到背风侧逐渐变细。沙丘沙比丘间地沙分选好，沙垅背风侧比迎风侧分选好。沙粒属极负偏，偏度－０．２２，丘间地沙比沙丘沙更趋向负偏。峰度１．３８，属尖峰态。粒径与偏度和峰度成正相关，分选和偏度成良好负相关。沙丘沙以单峰态为主，累积频率曲线为２～３段式，丘间地以双峰态为主，累积频率曲线为３～４段。大尺度地形对沙粒段式没有影响，对各段组分含量相对大小有影响。

GRAIN SIZE PARAMETERS ALONG THE TRANSECTION OF A COMPLEX LOGITUDINAL DUNE IN THE CENTER OF TAKLIMAKAN DESERT

Sands are taken from a complex logitudinal dune in the center of Taklimakan Desert which is about 4km long and 2km wide,and 50k high comparative to the interdune.The samples were cellected from areas of 20×20cm 2 to a depth of 0￣10cm. \ \ The results show that the mean diameter is from 2.88Φ￣3.3Φ with a 3.06Φ mean value,very fine sands are dominant.The mean diameter becomes gradully fine from the upwind slope to the down wind slope via the top of the longitudinal dune along the modern main wind direction,which indicates that the dune is growing up.The sorted index of dune sands,from 0.28 to 0.55,is smaller than that of interdune sands,form 0.32 to 1.23.The trend of two indexes are similar along the transection.The sand is -0.22 of very negative skewness,1.38 of leptokurtosis \ \ There is a positive relationship between the mean diameter and the skewness of the kurtosis.A good negative relationship occurs between the standard deviation and the skewness.Single mode dominates dune sands,and yet interdune sands are of two modes.