青藏铁路格尔木-拉萨段风成沙物源及其粒度特征

摘要/Abstract

摘要： 青藏铁路格尔木-拉萨段沿线地表松散沉积物广泛分布,为风沙活动的产生提供了丰富的物质来源。地表松散沉积物按成因分为现代风成沙,河流冲积物,古风成沙和洪积、湖积沉积物。粒度分析结果显示,格-拉段沿线风沙物质（沙丘沙、防沙体系积沙）样品（56个）平均粒径变化于1.29～3.25 Φ之间,均值2.36 Φ（0.19 mm）。平均粒径在2～3 Φ（0.25～0.125 mm）之间的样品占总数的78.57%。粒度组成以细沙为主（65.20%）,其次是中沙（20.53%）,0.5～0.1 mm范围重量百分比在49.44%～99.67%之间,平均为85.98%。在所有样品中,细沙和中沙合计在90%以上者占样品总数的55.36%。极细沙平均含量为7.99%,粗沙平均含量为5.50%。样品整体分选程度较好,标准偏差σ1在0.3～1.26之间,平均为0.58。偏度变化在-0.41到 0.36之间,样品中以正态分布为主,占53.57%;正偏者占12.50%;负偏者占19.64%;极负偏和极正偏各占7.14%。KG值变化于0.56～1.24,平均为1.00,为中等峰态。KG值在0.90～1.11之间者占71.43%。粒度分析表明,不同来源沙物质粒度特征有明显的差别,能很好地反映其形成过程和环境特征。

关键词: 风成沙, 来源, 粒度, 青藏铁路, 格拉段

Abstract: Loosen sediments extensively distributed along the Golmud-Lhasa section of the Qinghai-Tibet Railway can easily been transformed to aeolian sand by strong wind. The loosen sediments are mainly classified as current aeolian deposit, fluvial deposit, activated ancient dunes, alluvial deposit, and lacustrine deposit. Grain size statistical results show that the range of arithmetic mean diameters of dune sand samples are from 1.29 Φ to 3.25 Φ with a mean value of 2.36 Φ(0.19 mm). The fine sands and medium sands (0.1～0.5 mm) are dominant, which make up 49.44% to 99.67% percent in samples. These results are not conforming to the published data on wind-blown sands from other regions of China or other deserts in the world. The very fine sand content is 7.99% and coarse sand is 5.50%. Most of the sand samples are fairly sorted. The range of standard deviation is from 0.3 to 1.26 and the mean value is 0.58. Skewness values is from -0.41 to 0.36, with a mean value of -0.01. Most samples are symmetry and account for 53.57% of the total. Positive-skewed samples account for 12.50% and negative-skewed ones account for 19.64%. Both very positive-skewed and very negative-skewed are 7.14%. Kurtosis values are from 0.56～1.24 with a mean value of 1.00 and most samples are normal kurtosis and account for 71.43% of the total. The statistical results of grain size also show that the grain size characteristics have great difference for different sand sources, which reflect sand formation progress and environmental characteristics.

Key words: aeolian sand, source, grain size, Qinghai-Tibet Railway, Golmud-Lhasa section

中图分类号:

X144

姚正毅, 屈建军. 青藏铁路格尔木-拉萨段风成沙物源及其粒度特征[J]. 中国沙漠, 2012, 32(2): 300-307.

YAO Zheng-yi, QU Jian-jun. Source and Grain Size of Aeolian Sands along Golmud-Lhasa Section of Qinghai-Tibet Railway[J]. JOURNAL OF DESERT RESEARCH, 2012, 32(2): 300-307.

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