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作 者:朱春鸣 董治宝 刘铮瑶 肖南 杨军怀 冯淼彦 Zhu Chunming;DongZhibao;Liu Zhengyao;Xiao Nan;Yang Junhuai;Feng Miaoyan(School of Geography and Tourism,Shaanxi Normal University,Xi'an 710119,China;College of Earth and Environmental Sciences,Lanzhou University,Lanzhou 730000,China)
机构地区:[1]陕西师范大学地理科学与旅游学院,陕西西安710119 [2]兰州大学资源环境学院,甘肃兰州730000
出 处:《中国沙漠》2021年第2期9-18,共10页Journal of Desert Research
基 金:国家自然科学基金重点项目(41930641);国家自然科学基金面上项目(41871008)。
摘 要:树枝状沙丘是古尔班通古特沙漠独特的沙丘地貌类型。分析了古尔班通古特沙漠树枝状沙丘表层沉积物的粒度和微形态特征。结果表明:(1)树枝状沙丘以中砂为主,其次是细砂和粗砂;平均粒径与分选系数有较好的线性关系,平均粒径越小,分选系数越好;沉积环境以河流湖泊环境为主;石英颗粒形态以圆形和长形为主,磨圆度适中,碟形坑分布广泛,同时伴有硅沉淀现象,表明沉积作用以机械作用为主,同时还伴有化学作用。(2)整体上,粗砂和极粗砂含量西部最多,细砂含量南部最多,受风力分选作用的影响明显。西部的分选较其他区域好,东部分选较差;西部磨圆度最好,南部磨圆度最差。坡顶的中砂含量最多,迎风坡丘间地粗砂含量高于背风坡丘间地;迎风坡坡脚的细砂和中砂含量远远高于背风坡坡脚;沙丘的两翼部位粒级占比相对一致。(3)粒度和微形态特征都表明树枝状沙丘沉积物特征主要受风力分选作用的影响,同时受物源和植被的影响,共同揭示出河流湖泊的沉积环境。Dendritic dune is a unique type of dune landform in Gurbantunggut desert.This paper analyzes the grain size and micromorphological characteristics of the surface sediments of the dendritic dunes in the Gurbantunggut Desert.The results show that:(1)The dendritic dunes are dominated by medium sand,followed by fine sand and coarse sand.There is a good linear relationship between the average particle size and the separation coefficient.The smaller the average particle size,the better the sorting coefficient.The sedimentary environment is dominated by rivers and lakes.The shape of quartz grains is mainly round and long and the roundness is moderate.Dished pits are widely distributed and accompanied by the phenomenon of silicon precipitation,indicating that the deposition is mainly mechanical and accompanied by chemical action.(2)On the whole,the coarse sand and extremely coarse sand account for the most in the west while fine sand in the south,which is the result of wind separation.The sorting in the west is better than that in other regions while the sorting in the east is worse.The roundness in the west is the best while the roundness in the south is the worst.The medium sand at the top of the slope accounts for a large proportion.The content of coarse sand on the windward slope is higher than that of the leeward slope while the fine sand and medium sand content at the foot of the windward slope is much higher than that on the leeward slope.The proportion of grain size in the two wings of sand dune is relatively consistent.(3)The characteristics of grain size and micromorphology indicate that the dendritic sand dunes are mainly affected by wind separation as well as by material sources and vegetation,which jointly reveal the sedimentary environment of rivers and lakes.
关 键 词:古尔班通古特沙漠 树枝状沙丘 粒度 微形态 沉积环境
分 类 号:P931.3[天文地球—自然地理学]
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