雅鲁藏布江河谷沙丘沉积物粒度特征及其环境指示  

Grain size characteristics of sand dunes in the Yarlung Zangbo River valley, southern Tibetan Plateau and its environmental implications

作　　者：田伟东 杨军怀 王树源 马兴悦 夏敦胜[1] TIAN Weidong;YANG Junhuai;WANG Shuyuan;MA Xingyue;XIA Dunsheng(Key Laboratory of Western China's Environmental Systems(Ministry of Education),College of Earth and Environmental Sciences,Lanzhou University,Lanzhou 730000,China)

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,兰州730000

出　　处：《干旱区资源与环境》2022年第1期128-134,共7页Journal of Arid Land Resources and Environment

基　　金：第二次青藏高原综合考察研究项目(2019QZKK0602);兰州大学西部环境教育部重点实验室开放基金及兰州大学中央高校基本科研业务费专项资金(lzujbky-2020-kb01)资助。

摘　　要：雅鲁藏布江(雅江)河谷是青藏高原南部风成沉积物的典型分布区。通过对雅江河谷的沙丘表层沉积物进行系统采样,分析了沉积物粒度特征及其空间分异规律,以期揭示河谷风沙沉积环境。结果表明:1)沙丘沉积物粒度以细砂和中砂组分为主,其次为极细砂、黏土-中粉砂、粗砂和粗粉砂组分。分选较差至中等,偏度为正偏至极正偏,峰态介于正态至很尖锐。2)沙丘沉积物粒度组成及参数在流域尺度上并无统一的空间变化规律,但在雅江上游和中游存在明显区域差异。风沙过程是造成这种区域变化的主要原因,水沙过程并不是影响雅江河谷沙丘粒度变化的主要原因。3)雅江河谷沙丘沉积物具有相似的搬运方式和沉积环境,主要由跃移质和蠕移质组成,悬移组分含量低,沉积环境主要为河流沉积和湖泊沉积,共同指示河岸和河漫滩沉积物是雅江风成沙丘的主要物质来源。Yarlung Zangbo River valley is a typical distribution area of aeolian sediments in the southern Tibetan Plateau. Based on the systematic sampling of surface sediments of sand dunes in the river valley, we analyzed the grain size characteristics of dune sediments and their spatial differences, aiming to reveal the depositional environment of aeolian sand. The results show that: 1) The grain size of dune sediments is mainly composed of fine and medium sand, followed by very fine sand, clay and medium silt sand, coarse sand, and finally by coarse silt sand. The sorting coefficient is mostly between poor separation and medium separation, the skewness is mostly between positive deviation and extreme positive deviation, and the kurtosis is between normal and very sharp. 2) There is no obvious spatial variation in the grain size composition and parameters of dune sediments on the basin scale, but some significant differences are found in the upper and middle reaches of the river. The wind sand process is the main reason for this regional change, and the water sand process is not the main factor affecting the grain size change of dunes in Yarlung Zangbo River valley. 3) The sand dune sediments in the Yarlung Zangbo River valley have similar transport patterns and sedimentary environment, which are mainly composed of saltation and creep components, with low content of suspended component. The sedimentary environment of the dunes is mainly the fluvial and lacustrine sedimentary. These characteristics indicate that the riverside and floodplain sediments are the main material sources of aeolian dunes in Yarlung Zangbo River valley.

关 键 词：沙丘 粒度 物源 沉积环境 雅鲁藏布江 青藏高原南部 

分 类 号：X144[环境科学与工程—环境科学]