文章摘要
董苗, 严平, 孟小楠, 吴伟.青藏高原爬坡沙丘地表沉积物特征分析——以柴达木盆地托拉海河为例[J].水土保持学报,2018,32(4):101~108
青藏高原爬坡沙丘地表沉积物特征分析——以柴达木盆地托拉海河为例
Characteristics of Surface Sediments of the Climbing Dunes on the Qinghai-Tibetan Plateau——Taking the Tola Hai River in the Qaidam Basin as an Example
投稿时间:2018-03-13  
DOI:10.13870/j.cnki.stbcxb.2018.04.016
中文关键词: 粒度  化学元素  物源  风化过程  爬坡沙丘  托拉海
英文关键词: grain size  chemical elements  sediments provenance  weathering process  climbing dunes  Tola Hai River
基金项目:国家重点研发计划项目(2016YFA0601901);国家重点基础研发计划项目(2013CB956001)
作者单位E-mail
董苗1,2,3, 严平1,2, 孟小楠1,2, 吴伟1,2 1. 北京师范大学地理科学学部, 北京 100875

2. 北京师范大学地表过程与生态环境重点实验室
, 北京 100875

3. 防沙治沙教育部工程研究中心
, 北京 100875 
yping@bnu.edu.cn 
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中文摘要:
      为了阐明青藏高原爬坡沙丘的物源及沉积学意义并揭示其形成机理,对托拉海河爬坡沙丘进行断面采样,分析爬坡沙丘不同地形部位的粒度与地球化学元素特征。结果表明,托拉海河爬坡沙丘地表沉积物的粒度组成总体以极细砂、细砂、中砂为主,粒度特征表现出明显的风成特点;不同地形部位,粒度特征呈现不同的递变规律,自河床到迎风坡顶粒径变粗,分选变好,迎风坡顶到背风坡,粒径粗细混杂,分选变差。沉积物地球化学元素组成以Si、Al、Ca为主,和上陆壳(UCC)相比,除Co、As、CaO、SiO2以外,其余元素都有一定的亏损,不同部位化学元素分布具有一定相似性,且常量氧化物之间有较好的相关性,表明其具有相似的沉积环境。A-CN-K图解及CIA值揭示了托拉海河爬坡沙丘地表沉积物化学风化处于较低程度,大部分化学元素没有显著的风化或迁移,整体属于早期去Na、Ca的阶段;A-CNK-FM图则表明整个断面Fe、Mg元素在空间分布上存在一定的差异,Fe、Mg流失主要是差异风力风选的结果。从化学风化指标来看,不同地形部位风化程度不同,河床风化程度最弱,山地迎风坡的风化程度最强;河床与河流阶地的物源呈现多样性,而迎风坡和背风坡物源较为单一,可能是古沙翻新和就地起沙。因此,初步认为托拉海河爬坡沙丘的形成经历了两个阶段:一是古沙丘形成阶段;二是现代爬坡沙丘形成阶段。在不同空间尺度上,托拉海河爬坡沙丘地表沉积物的理化特征差异与风动力和水动力的差异有关,反映出沉积物对风、水交互作用的响应。
英文摘要:
      In order to clarify the source and sedimentological significance of the climbing dunes on the Qinghai-Tibetan Plateau and reveal its formation mechanism, the climbing dunes section samples were collected in the Tola Hai River, and the grain size and geochemical characteristics of the different terrain parts of the climbing dunes were analyzed. The results showed that the grain size of the climbing dunes of Tola Hai River mainly consisted of very fine, fine and medium sand with an obvious aeolian sedimentary characteristic. The characteristic of particles varied in different terrain; the mean grain size became coarser from the riverbed to upwind slope, meanwhile, the sorting trended to be better, but the opposite trend was observed from the upwind slope to the leeward slope. The geochemical evidence indicated that in the climbing dunes of Tola Hai River, Si, Al and Ca were the dominant elements. Compared with the upper continental crust (UCC), all the elements except Co, As, CaO and SiO2 appeared to a depletion status. The distribution of chemical elements in different terrain was similar, and there was a good correlation between constant oxides, indicating that they had similar sedimentary environment. The A-CN-K ternary diagram and the CIA index showed that chemical weathering of the surface sediments in the climbing dunes was in a low degree, most of the chemical elements had no significant weathering or migration, and the whole was in the stage of early Na and Ca. Moreover, A-CNK-FM ternary diagram showed that the spatial distributions of Fe and Mg were different in the whole section and the loss of Fe and Mg was mainly caused by sorting action of wind. All the chemical weathering index, including CIA, A-CN-K and A-CNK-FM, presented that different topographic parts were in different weathering degrees, the weathering degree of the river bed was the weakest, the weathering degree of the upwind slope was the strongest. The source of the riverbed and river terrace was diverse, while the source of windward slope and leeward slope was relatively single, which may be caused by ancient dunes activated and local sand source or local accumulation. Therefore, we preliminarily believed that the formation of the climbing dunes in the Tola Hai River has undergone two stages:the first was the formation of the ancient dunes and the second was the formation of modern climbing dunes. On different spatial scale, the physical and chemical characteristics of the surface sediment of climbing dunes were related to the difference between power of wind and hydrodynamic force, reflecting the response of the sediment to the interaction of wind and water.
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