青藏高原东缘风成黄土的多源性——以九寨沟黄土为例  

Multi-material Source of Loess Deposits from the Jiuzhaigou National Nature Reserve on the Eastern Margin of the Tibetan Plateau

作　　者：文星跃[1] 唐亚[2] 黄成敏[2] 贡波索郎 

机构地区：[1]绵阳师范学院生态安全与保护四川省重点实验室,四川绵阳621000 [2]四川大学环境科学与工程系,四川成都610065 [3]四川九寨沟自然保护区管理局,四川阿坝623402

出　　处：《山地学报》2014年第5期603-614,共12页Mountain Research

基　　金：新世纪优秀人才支持计划项目(NCET-08-0379);高等学校学科创新引智计划项目(B08037);四川省教育厅科研项目(13ZA0115);绵阳师范学院科研启动项目(QD2013A08)资助~~

摘　　要：黄土是研究环境变化的重要材料,揭示其物源及成因有利于解译其蕴含的环境信息。分析位于青藏高原东缘的九寨沟自然保护区黄土地层的矿物组成、粒度、稀土和微量元素、石英砂表面形态,进而探讨九寨沟黄土的物源及成因意义。结果表明:研究区黄土属风成沉积物,黄土物质既有来自邻近地区的冰缘沉积物,也包含北方远源的风尘物,具有多源性特征;青藏高原东缘黄土与南缘黄土的物源明显不同,揭示出青藏高原内部的冷高压对其边缘地带黄土沉积并无直接作用,而局地的山谷风对黄土沉积可能贡献更大。因此,利用青藏高原边缘地带的黄土研究环境变化需重视地形因素,同时应加强多剖面的对比。此外,稀土元素分配模式对黄土物源的指示意义具有不确定性。As an important archive to record environmental change,loess deposits need to be understood in terms of formation and material source to further reflect environment information.The formation of loess deposits and the provenance of loess material in the Jiuzhaigou National Nature Reserve on the eastern margin of the Tibetan Plateau were investigated based on the proxies of mineralogy,grain size distribution,rare earth and trace elements,and morphology of quartz grains in loess deposits.The results show that（1） the loess deposits in the study region are windblown dust accumulation derived from both neighboring glaciofluvial outwash deposits and remote windblown dusts;（2） the source of loess material in the study region differs from that of the southern margin of the Tibetan Plateau,indicating that the formation of loess deposits on the margin region of the plateau coupled with the mountain-valley breeze rather than the cold high pressure of the Plateau.Moreover,it should be cautious to judge the source of loess deposits using the pattern of rare earth elements.

关 键 词：黄土沉积 物源 成因 九寨沟自然保护区 青藏高原东缘 

分 类 号：P534.63[天文地球—第四纪地质学] P642.131[天文地球—古生物学与地层学]