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西藏定结地区爬坡沙丘粒度特征分析 被引量:13

Grain size characteristics of the climbing dunes in Dinggye area of Tibet
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摘要 通过对西藏定结地区典型爬坡沙丘表层沉积物的形态参数、粒度组成和粒度参数等进行分析,揭示其粒度特征。结果表明:(1)爬坡沙丘表层沉积物以细砂和中砂为主,极细砂含量较少,同时含有少量粉砂和粗砂,不含粘土成分。(2)沙丘平均粒径范围1.98~2.41Ф,分选系数变化范围为0.45~0.75,属中等分选,偏度变化范围为0.01~0.12,呈近对称至正偏分布,峰度变化范围为0.94~1.01,呈中等尖锐峰态。(3)从样品PPSQ1~PPSQ6,随着高度和距离的增加,沙丘表层沉积物平均粒径先变细后变粗,分选不断变好。(4)爬坡沙丘表层沉积物主要来源于河漫滩。(5)与雅鲁藏布江、东昆仑山地区爬坡沙丘对比可知,定结地区的沙丘粒径较粗,分选较好,主要是物源及风力分选作用的共同结果。 The climbing dunes are widely distributed in Dinggye area of Zigaze Prefecture,Tibet,China,and the surface sediment grain size characteristics are of great significance for exploring the development process of sand dunes.In this paper,six climbing dunes sand were collected in the area.In order to reveal the grain size characteristics,the study analyzed the morphological parameters,mechanical composition and grain size parameters of surface sediments of the dunes,which provide a theoretical basis to reveal the climbing dune’s formation mechanism on the Qinghai-Tibet Plateau.The current researches were mainly concentrated on the climbing dunes in coastal areas rather than that in arid areas.Studying the climbing dunes on the Qinghai-Tibet Plateau can explore the grain size characteristics of climbing dunes in inland arid regions.The results are summarized as follows:The surface sediments of climbing dunes are mainly composed of silver sand and medium sand,accounting for 55.25% and 32.73% respectively.Fine sand accounts for 9.98%.The content of silty and coarse sand are less than 3%.The frequency curves of grain size are showing an approximate symmetrical unimodal distribution,and sand dunes have a slender tail on one side of the fine particles.The range of Mz is 1.98-2.41 Ф and the mean value is 2.23 Ф.The range of σ is 0.45-0.75 and the mean value is 0.57,which is good for middling sorting.The range of SK is 0.01-0.12,the mean value is 0.04,and kurtosis is positive.The range of KG is 0.94-1.01,the mean value is 0.97,and kurtosis presents a single peak.As the height and distance increasing,the Mz of the climbing dunes trends to be thinner first and later coarser,the sorting gets better.The variation trend of grain size characteristics of different parts of sand dunes is as follows:The Mz from the windward and the leeward slope to the top of the leeward is generally coarser,and the sorting is worse.The variation trend of SK is from near symmetry to positive deviation,and the KG has a medium sharp.The reason for its differentiation is mainly affected by the source and wind sorting.The analysis of the sources of the sediment reveals that the dune surface sediment is mainly from the floodplain.Comparing with the climbing dunes in the Yarlung Tsangpo River and the eastern Kunlun Mountains,the surface sediments of the climbing dunes in the study area is coarser and the sorting is relatively better.It indicates that the climbing sand dunes are closer to the source area,and the wind sorting effect is stronger in Dinggye than the other two areas.
作者 潘美慧 薛雯轩 伍永秋 黄文敏 马建军 杨安娜 陈玉林 PAN Mei-hui;XUE Wen-xuan;WU Yong-qiu;HUANG Wen-min;MA Jian-jun;YANG An-na;CHEN Yu-lin(College of Geography and Environment Science,Northwest Normal University,Lanzhou 730070,Gansu,China;Engineering Research Center of Ministry of Education,Beijing Normal University,Beijing 100875,China;The Second Affiliated Middle School Future Science City School of Beijing Normal University,Beijing 102209,China)
出处 《干旱区地理》 CSCD 北大核心 2019年第6期1337-1345,共9页 Arid Land Geography
基金 国家自然科学基金项目(41807448)
关键词 爬坡沙丘 粒度特征 定结地区 climbing dune grain size characteristics Dinggye area
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