李安琪,
赵晓萌,
程宏,,
李慧茹,
亢力强
北京师范大学地理科学学部，北京师范大学地表过程与资源生态国家重点实验室，北京师范大学防沙治沙教育部工程研究中心： 100875，北京
基金项目:国家重点研发计划资助项目（2016YFC0500800）；国家自然科学基金资助项目（41771006）
详细信息
通讯作者:程宏（1975-），男，博士，教授级高级工程师. 研究方向：风沙物理和荒漠化防治方面的教学与研究. E-mail：chengh@bnu.edu.cn
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出版历程
收稿日期:2020-09-20
网络出版日期:2021-07-07
刊出日期:2021-09-02
Developmental scale and wind direction influence particle size characteristics of surface sediments over barchan dunes at southeastern edge of the Taklimakan Desert
Ning JIANG,Anqi LI,
Xiaomeng ZHAO,
Hong CHENG,,
Huiru LI,
Liqiang KANG
Faculty of Geographical Science; State Key Laboratory of Earth Surface Processes and Resource Ecology; Engineering Center of Desertification and Blown-Sand Control of Ministry of Education：Beijing Normal University，100875, Beijing, China
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摘要
摘要:以塔克拉玛干沙漠东南缘新月形沙丘为研究对象，分析3个不同发育规模和相反风向作用后沙丘表面沉积物粒度参数，得出以下结论：1）新月形沙丘表面沉积物以砾石和极粗沙为主，二者总占比79.09%，与之对应的，沉积物概率累积曲线多以蠕移质为主，其次为跃移质．沙丘形态及其表面微地貌变化，使得沉积物粒度特征在沿风向的不同断面呈现3种模式：迎风坡脚最粗、沿迎风坡经丘顶/脊线至背风坡脚逐渐变细，分选丘顶/脊线最好、由此分别至迎/背风坡脚变差；迎风坡上/下部最粗、由此至迎/背风坡脚变细，分选丘顶/脊线最好、由此至迎/背风坡脚变差；迎风坡上/下部最粗、由此至迎/背风坡脚变细，分选迎风坡脚最好、沿迎风坡经丘顶/脊线至背风坡脚变差．2）随沙丘高度增加，迎风坡和背风坡沉积物先变细后变粗，丘顶/脊线逐渐变粗，但分选性均变好；两翼角沉积物粒径差值增大，粒径粗、分选好的短翼角变为长翼角．3）相对于区域主风向（NE），反风向（SW）作用后，迎风坡沉积物变细、分选变差，丘顶变粗、分选变好，背风坡脚变细、分选无明显变化．迎风坡表面和背风坡脚细沙、极细沙和粉沙总占比增加，砾石和极粗沙总占比减少；丘顶正相反．
关键词:塔克拉玛干沙漠/
新月形沙丘/
粒度特征/
沙丘形态/
风向
Abstract:Particle size characteristics of surface sediments over Barchan dunes are the result of interactions of dune morphology, regional airflow and sand flux．These are also key parameters to understand dune morphology and dynamic formation．Particle size parameters of surface sediments over dunes were analyzed on three developing scales at southeastern edge of the Taklimakan Desert．Their changes with two opposite wind directions were also investigated．Gravel and very coarse sand were found to be the main components of surface sediments over dunes, accounting for 79.09% of total．Probability cumulative curves of sands were mostly composed of creep component, to a lesser extent of saltation component．Dune morphology and surface microgeomorphology resulted in three modes for grain size characteristics of sediments in different longitudinal axes over dune．First, sediments at the windward slope toe were the coarsest and gradually became finer along windward slope through crest/brink to leeward slope toe, while these in crest/brink had the best sorting and the sorting gradually became worse from the crest/brink to windward slope toe and lee slope toe．Second, sediments at the upper or lower windward slope were the coarsest and gradually became finer along windward slope to the toe and through crest/brink to lee slope toe, while the sorting on the crest/brink was better than other locations and gradually became worse along windward/lee slope to the toe．Third, grain size distributions were similar to the second, while the windward slope toe was the location with best sorting and the sorting gradually became worse along windward slope to the lee slope toe．With the increase in dune height, the sorting of sediments over dune surface became better, while their particle sizes took on different characteristics．Their particle sizes initially became finer and then coarser along windward and leeward slopes, while became coarser at crest/brink．Difference in particle sizes at two horns increased, short horn with the smaller particle size and better sorting converted to long one．Compared with action of airflow with main wind direction (NE), sediments along the windward slope and at the toe of lee slope became finer under action of airflow with wind direction of SW, while the former sorting became worse and the latter had no obvious change．The sediments at the crest became coarser and their sorting became better．The content of fine sand, very fine sand and silty sand along the windward slope and at the toe of lee slope increased, while the content of gravel and very coarse sand decreased．Changes in sediment composition at the crest were opposite to windward slope．
Key words:Taklimakan Desert/
barchan dune/
grain size characteristics/
dune morphology/
wind direction
