准噶尔中南部沙尘暴源区地表沉积物粒度特征

对准噶尔中南部沙尘暴源区——艾比湖地区、克拉玛依农业开发区和古尔班通古特沙漠地表沉积物粒度组成、传统粒度参数及分维值进行了分析计算,结果表明:艾比湖流域及克拉玛依开发区广泛分布的沙质、粘土质、盐土荒漠区,特别是春季翻耕的大面积裸露农田地表物质含有大量小于0.063mm的粉砂和粘土,且粒度分维值较高,是沙尘暴的丰富物源。古尔班通古特沙漠风成沙粒径较粗,分维值较低,加之较好的植被状况,沙尘暴发生频数相对较低。粒度参数C-M图、M_z-S₀散点图和粒度分维值可以有效地表征地表松散物质的搬运-沉积特征,是描述沙尘暴发生地表条件的重要指标。

Characteristics of Grain Sizes for Surface Sediments on Source Regions of Sand-dust Storms in Mid-south Junggar Basin

The Aibi Lake catchment,the developed agricultural region of Kelamayi and the Gurbantunggut Desert are sources of sand-dust storms in the mid-south Junggar Basin.The analyzing results of surface grain size component,traditional grain size parameters and fractal dimensions show that,in Aibi Lake catchment and the developed agricultural region of Kelamayi,the widespread sandy,clay and salt deserts,especially the extended bare farmland after plough in spring,are abundant sources of sand-dust storms.Their surface materials consist of a great number of silt and clay of <0.063 mm with the content of over 50% and higher fractal dimension.The grain sizes of the aeolian sands in the Gurbantunggut Desert are coarser and with lower fractal dimension,in addition,the desert has better vegetation status,so the frequency of sand-dust storms in the desert is correspondingly low.The C-M and M_(z)-S_(0) diagrams and fractal dimensions can effectively indicate the transporting and depositing characteristics of loose surface sediments,and they are the important indices for describing the ground surface condition of sand-dust storms.