青藏高原不同气候带爬坡沙丘沉积物特征及其环境指示  

Sediment characteristics and environmental significance of climbing dunes in different climatic zones of the Qinghai-Tibet Plateau

作　　者：董苗 严平 王晓旭[2,3] 吴伟 王勇 孟小楠 王一娇 纪欣然 DONG Miao;YAN Ping;WANG Xiaoxu;WU Wei;WANG Yong;MENG Xiaonan;WANG Yijiao;JI Xinran(School of Geography Science,Taiyuan Normal University,Jinzhong 030619,Shanxi,China;State Key Laboratory of Earth Surface Processes and Resource Ecology,Beijing Normal University,Beijing 100875,China;Faculty of Geographical Science,Beijing Normal University,Beijing 100875,China;State Key Laboratory of Earth Surface Processes and Resource Ecology Zhuhai Base,Beijing Normal University,Zhuhai 519087,Guangdong,China;College of Urban and Environmental Sciences,Hubei Normal University,Huangshi 435002,Hubei,China;Institute of Geographical Sciences,Henan Academy of Sciences,Zhengzhou 450052,China)

机构地区：[1]太原师范学院地理科学学院,晋中030619 [2]北京师范大学地理科学学部地表过程与资源生态国家重点实验室,北京100875 [3]北京师范大学地理科学学部,北京100875 [4]北京师范大学地表过程与资源生态国家重点实验室珠海基地,珠海519087 [5]湖北师范大学城市与环境学院,黄石435002 [6]河南省科学院地理研究所,郑州450052

出　　处：《地理学报》2023年第7期1825-1846,共22页Acta Geographica Sinica

基　　金：国家自然科学基金项目(41871010,42101013);第二次青藏高原综合科学考察研究(2019QZKK0906);中国林业科学研究院重点项目(CAFYBB2018ZE002);山西省高等学校科技创新项目(2020L0502)。

摘　　要：爬坡沙丘是高原山区广布的一种重要的障碍沙丘类型,其形成主要受地形、沙源和风动力的影响。已有的研究侧重于模拟试验、分布规律、野外观测和沙丘形态等方面,从区域尺度解析不同气候带爬坡沙丘沉积物特征及环境意义的研究还相对缺乏。本文从风沙地貌学、粒度沉积物、地球化学等方面综合分析青藏高原不同气候带爬坡沙丘的风能环境、近地表流场、沉积物特征及物源等。结果表明:①由于物源差异,不同气候区爬坡沙丘沉积物粒度组成不同,主要为细沙和中沙,半湿润区分选好而干旱区分选差;不同地貌部位沉积物的粒度差异较小,且与近地表气流有较好的响应,就地起沙是其形成的基本形式,其中细沙爬坡能力最强。②母岩特征和气候环境影响沉积物的化学元素含量,但粒径大小也是造成其空间差异的关键,微量元素主要集中于河漫滩且不同地貌部位差异较小。③沉积物中常量元素除SiO2富集外,其他均呈现不同程度的淋失或富集,微量元素大多亏损,淋失与富集程度与粒径密切相关。④青藏高原爬坡沙丘沉积物处于大陆风化初期,半湿润区风化程度较强,不同地貌部位沉积物的风化差异较大,与母岩性质、气候环境及沉积分异有关。Climbing dunes are important barrier dunes that are widely distributed in highland mountain regions,and their formation is mainly controlled by topography,sand sources and wind regime.Existing researches mainly focus on simulation experiments,distribution patterns,field observations,and morphological characteristics.From a regional scale,there is a lack of research to analyze the variations in sediment characteristics and environmental significance of climbing dunes in different climatic regions.In this study,the wind regime,near-surface airflow,sediment characteristics and material sources of climbing dunes on the Qinghai-Tibet Plateau were comprehensively analyzed from the aspects of aeolian geomorphology,grain-size sedimentology,and geochemistry.The results show that:(1)Due to differences in material sources,the grain-size composition of climbing dunes sediments in different climatic areas varies,primarily fine and medium sands,with good sorting in the semi-humid areas and poor sorting in arid areas.The grain-size difference of sediments in different geomorphic parts is small,and it responds well to near-surface airflow,and in-situ sand accumulation is the basic formation form,with fine sand having the strongest climbing ability.(2)The chemical element content of sediments is influenced by the parent rock characteristics and the climatic environment,and the particle size is also important to its spatial variation,and trace elements are primarily concentrated in river floodplains,with little variation between geomorphic sites.(3)Except for SiO2 enrichment,all macronutrients in the sediment show varying degrees of leaching or enrichment,and the majority of trace elements are deficient,as leaching and enrichment are closely related to particle size.(4)Climbing dunes sediments are in the early stage of continental weathering,with higher weathering levels in the semi-humid zone.The weathering of sediments in different geomorphic sites varies substantially,which is related to the parent rock,climatic environment,and

关 键 词：爬坡沙丘 粒度沉积学 地球化学 不同气候带 青藏高原 

分 类 号：P931.3[天文地球—自然地理学]