末次冰期旋回风成沉积物图解法与矩值法粒度参数的对比  

Grain Size P?arameters of Loess-palaeosol Deposits from Graphic and Moment Methods: A Comparative Study

作　　者：徐树建[1] 潘保田[1] 张慧[1] 李琼[1] 

机构地区：[1]兰州大学资源环境学院西部环境教育部重点实验室

出　　处：《干旱区地理》2005年第2期194-198,共5页Arid Land Geography

基　　金：国家重点基础研究发展规划项目"青藏高原各圈层相互作用综合研究"(G1998040811);国家自然科学基金(40171010;40471016;40401007);教育部重点项目(200330017)资助

摘　　要：运用GRADISTAT粒度处理软件,分别计算了末次冰期黄土高原西部等地的黄土古土壤和风成砂的粒度参数,并对图解法与矩值法粒度参数进行了对比。结果表明,对黄土古土壤来说两种方法所获得的平均粒径基本相同,分选系数、偏度和偏态的相关性逐渐降低。对风成砂和砂黄土来说,除了平均粒径呈较好的线性相关外,其它参数则差别很大。造成这种差异的主要原因是它们的粒度组分的分布不同。黄土古土壤的粒度分布尽管呈双峰分布,但次峰通常较小,故尾部部分对粒度参数影响不大;而风成砂和砂黄土的次峰的频数较大,对粒度参数的影响很大。图解法主要反映了主要粒度组分的粒度特征,而矩值法则反映了样品的总体特征。在沉积环境的分析和比较时,应充分考虑这两种方法的差异,建立不同的等级标准。Grain size is the most fundamental property of sediment particles, affecting their entrainment, ○·environment changes in Quaternary in North China. GRADISTAT is a grain size distribution and statistics package for the analysis of unconsolidated sediments. Grain size parameters of about 240 aeolian sediment samples from the western Chinese Loess Plateau and other regions, were calculated using graphic and moment methods by GRADISTAT.A comparison between grain size parameters (including mean, sorting, skewness and kurtosis)of graphic and moment method shows that the mean grain size and sorting are almost identical, and there is a significant liner relationship between the two datasets for skewness and kurtosis in loess-paleosol sequence during the last glacial cycles. But it is different to the sand deposits near desert. Graphic method reflects the characteristics of a main part of a sample. There are large differences in grain size distribution between loess and sand deposits apart from this. So the differences in the two methods must be taken into account in sedimentary environment studies.

关 键 词：粒度参数 图解法 末次冰期旋回 风成沉积物 黄土古土壤 平均粒径 风成砂 处理软件 黄土高原 分选系数 线性相关 双峰分布 粒度分布 参数影响 粒度特征 总体特征 沉积环境 等级标准 砂黄土 相关性 组分 频数 样品 

分 类 号：P531[天文地球—古生物学与地层学]