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中国沙漠 ›› 2022, Vol. 42 ›› Issue (4): 22-31.DOI: 10.7522/j.issn.1000-694X.2021.00174

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拉萨河谷爬坡沙丘沉积物特征

王晓枝(), 董治宝(), 南维鸽, 李超, 高冲, 张欣   

  1. 陕西师范大学 地理科学与旅游学院,陕西 西安 710119
  • 收稿日期:2021-09-30 修回日期:2021-11-17 出版日期:2022-07-20 发布日期:2022-08-29
  • 通讯作者: 董治宝
  • 作者简介:董治宝(E-mail: zbdong@snnu.edu.cn
    王晓枝(1998—),女,陕西宝鸡人,硕士研究生,研究方向为风沙地貌。E-mail: xzwang@snnu.edu.cn
  • 基金资助:
    第二次青藏高原综合科学考察研究项目(2019QZKK0403)

Sediment characteristics of climbing dunes in Lhasa River Valley, China

Xiaozhi Wang(), Zhibao Dong(), Weige Nan, Chao Li, Chong Gao, Xin Zhang   

  1. School of Geography and Tourism,Shaanxi Normal University,Xi'an 710119,China
  • Received:2021-09-30 Revised:2021-11-17 Online:2022-07-20 Published:2022-08-29
  • Contact: Zhibao Dong

摘要:

分析了青藏高原拉萨河谷爬坡沙丘表层及不同深度沉积物的粒度和地球化学元素特征。结果表明:(1)爬坡沙丘表层沉积物以细沙为主,平均粒径为2.51Φ(细沙),分选中等,粒度分布曲线为正偏、窄峰。随海拔升高,表层沉积物逐渐变细;随深度增加,沉积物粒径逐渐变细。(2)爬坡沙丘沉积物常量元素中SiO2含量最高,微量元素中Ba含量最高。常量元素含量多随深度增加而减少,且在0—10 cm深度内变化幅度最大。与上部陆壳平均化学组成相比,除Na2O、MnO、Cr、Co、Mo、SiO2外,其余元素均处于亏损状态。拉萨河谷爬坡沙丘经历了中等的化学风化,处于大陆风化的早期阶段。

关键词: 拉萨河谷, 爬坡沙丘, 沉积物, 粒度, 地球化学元素

Abstract:

In order to promote the research on climbing dunes in Lhasa River Basin, this paper takes the climbing dune in Lhasa River Valley in the south of Qinghai Tibet Plateau as the research object, and analyzes the characteristics of grain size and geochemical elements of dune sediments on the surface and at the depth of 0-60 cm. The results show that: (1) Fine sand is the dominant particle size of surface sediments of climbing dune in Lhasa River Valley, followed by medium sand and very fine sand, with less silt content and very few coarse sand and clay. All samples do not contain very coarse sand, with an average particle size of 2.51 Φ (fine sand), medium sorting, positive skewness and narrow kurtosis. With the increase of altitude, the particle size of surface sediment gradually becomes smaller, and with the deepening of depth, the particle size of sediment gradually becomes thicker, with the maximum change in the range of 0-10 cm. (2) The SiO2 content of major elements is the highest, the variation coefficient of CaO is the largest, the Ba content of trace elements is the highest, and the variation coefficient of Co is the largest. Except SiO2 and K2O, the content of major elements decreases gradually from surface to deep layer, and the content change of trace elements from surface to deep layer can be divided into stable type, decreasing type, increasing type. The content of both major and trace elements changes most strongly at 0-10 cm. Compared with the average chemical composition of the upper continental crust, except that Na2O, MnO, Cr, Co and Mo are partially enriched, and the SiO2 content is equivalent to that of the upper continental crust, the rest are in a loss state. In terms of weathering degree, the chemical weathering degree of climbing dunes in Lhasa River Valley is higher than that of other deserts. They have experienced moderate chemical weathering. They are the products of the first cyclic deposition in arid and cold environment. Their composition characteristics are mostly similar to the upper continental crust and are in the early stage of continental weathering.

Key words: Lhasa River Valley, climbing dunes, sediment, grain size, geochemical elements

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