关键词: 撒哈拉沙漠, 粒度分析, 成因与环境

Abstract: The sand sample grain-size measurements show that the 36 desert sand samples takenfrom northeastern Sahara Desert, Sudan, in Africa can be divided into 10 different types; the grain-size indies are in the range asfollows: median diameter M_Z=1.34~2.43, the-stand arddeviation δ_I=0.51~1.43; skewness SK_I may be either positive or negetive, bu-tranges from-0.30~0.47, K_G=0.66~1.04, most of the grain-size frequence curves of the samples have the characteristics of multipeaks or double peaks, which is the typical structure o friver sand; On the other hand, there is noregular regional grain size distribution patterns in the investigation area. The analytical results reveal that the sand grain of northeastern Sahara was formed under the river-lacustrine deposition environment during warm-humid climatic condition and had been reformed by wind action later.

Key words: Sahara Desert, Grain-size analysis, Formation environment