凌智永^1,2,,
陈亮¹,
芦宝良¹,
王建萍¹,
陈发虎^2,3,,
1. 中国科学院青海盐湖研究所, 中国科学院盐湖资源综合高效利用重点实验室, 青海 西宁 810008
2. 兰州大学资源环境学院, 西部环境教育部重点实验室, 甘肃 兰州 730000
3. 中国科学院青藏高原地球科学卓越创新中心, 北京 100101


详细信息

作者简介: 凌智永, 男, 34岁, 博士研究生/助理研究员, 干旱环境与气候变化研究, E-mail:lingzhiyong@foxmail.com

通讯作者: 陈发虎, E-mail:fhchen@lzu.edu.cn

中图分类号: P597⁺.3

收稿日期:2017-08-26
修回日期:2017-11-09
刊出日期:2018-05-30

Chronology and provenance of the nebkhas around salt lakes in the Qaidam Basin and their environmental implication

Ling Zhiyong^1,2,,
Chen Liang¹,
Lu Baoliang¹,
Wang Jianping¹,
Chen Fahu^2,3,,
1. Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lakes Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai
2. Key Laboratory of Western China's Environmental System(Ministry of Education), College of Earth Environmental Sciences, Lanzhou University, Lanzhou 730000, Gansu
3. CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101


More Information

Corresponding author: Chen Fahu,E-mail:fhchen@lzu.edu.cn

MSC: P597⁺.3

--> Received Date: 26 August 2017
Revised Date: 09 November 2017
Publish Date: 30 May 2018


摘要
摘要:柴达木盆地盐湖周边灌丛沙丘广泛发育，但有关其发育年龄、物源及其对气候环境、风沙活动的响应过程尚不清楚。为此，对该区域灌丛沙丘进行了沙丘年代、沉积物稀土元素特征等方面的研究，并结合柴达木盆地周边区域风沙活动、古气候变化的研究成果，探讨了灌丛沙丘发育年龄及过程、物质来源及其对干旱环境的响应关系。结果表明：柴达木盆地盐湖周边灌丛沙丘自末次冰盛期以后开始发育，且沙丘年龄变量与深度变量之间存在Y=0.188X+0.276的方程式，其相关系数R²=0.539，置信水平为0.99%，呈极显著相关。随气候变干，灌丛沙丘在中、晚全新世以后达到较大规模，其形成发育是对全新世干旱气候的响应过程，并对35°N夏季太阳辐射强度变化、新仙女木事件有较好反映。全球末次冰盛期以后，随气候转暖东昆仑山冰川融水携带的第四纪沉积物在山麓形成的冲洪积扇碎屑经风化、搬运、沉积过程，为灌丛沙丘发育提供了丰富的物质基础；其风沙物质来源并非气候干旱期湖水退缩后湖底沉积物的风化产物。此外，冰川融水可能为植被生长提供了必备条件，植被发育为灌丛沙丘发育提供了保障。
关键词: 灌丛沙丘/
年代/
物源/
环境/
柴达木盆地

Abstract:The Qaidam Basin is located in the northeastern part of the Qinghai-Tibet Plateau, which has an extremely cold and dry environment. The Qaidam Basin is considered to be one of the highest and most arid desert on the earth, which is the main dust source area of the Loess Plateau during Quaternary glaciation and glacial substage. Due to the strong sandstorm activity in the Qaidam Basin, there are many types of sand sedimentary geomorphology, such as ancient dunes, nebkhas, etc. The extensively developed nebkhas are found in many parts of the Qaidam Basin, which height are from a few meters to more than ten meters. The nebkhas are mainly distributed along the northern foothills of the East Kunlun Mountains, which is a zonal region from the east to the west(36°15'~36°55'N, 93°20'~96°50'E). The nebkhas and the other aeolian landforms were be considered that their sand source were the sediments of the lake, and the aeolian sediments from lake bottom weathered and eroded, transported, and then accumulated in the edge of the basin. The aeolian sand develops a large number of sandy landform types, but there is not a necessary evidence of the sediments source. In addition, the chronology of nebkhas, the sandy material source of nebkhas, and their response to the climate and sandstorm activities are not clearly known around salt lakes in the Qaidam Basin.
In this study, the chronology of nebkhas, and the rare earth elements(REEs) characteristics of the aeolian sediments from the nebkhas were studied around salt lakes in the Qaidam Basin. We also compared the environment recorded by nebkhas with the research results of the sandstorm activities and the paleoclimatic reports in the surrounding areas of the Qaidam Basin. The relationship between the age and the development processes of these nebkhas have been studied by us. And the sedimentary material source of the nebkhas and their response to arid environment are discussed too. The results show that the nebkhas in the Qaidam Basin have developed after the Last Glacial Maximum(LGM). As the climate getting dry gradually, the nebkhas have reached the larger scale since the Middle and Late Holocene. The changes of the summer insolation at 35°N and the Younger Dryas event are recorded by the nebkhas, which formation and development are the response to the Holocene arid climate. There is a significant correlation between the age variation and the depth variation of the nebkhas, and the equation is Y=0.188X+0.276 with the correlation coefficient R²=0.539 which confidence level is 0.99%. The REE values vary from 119.72 μg/g to 154.39 μg/g with the value 6.70~8.39 of LREE/HREE ratios. The values of(La/Yb)_N vary from 6.71 to 9.49, and the values of the δEu and the δCe are 0.57~0.69 and 0.98~1.01, respectively. The(La/Yb)_N-ΣREE values show that the sand sources of the nebkhas are the alluvial fan detritus sediments which are from the northern foothills of the East Kunlun Mountains.
After the Last Glacial Maximum in the world, the Quaternary sediments were carried by the melting water to the foothills of East Kunlun Mountains, which became the alluvial fan debris, and then through the weathering, handling, deposition process, providing a rich material basis for the development of nebkhas. Therefore, the sedimentary material source of the nebkhas is not the weathering erosive of the lake sediments, which were exposed to the lake bottom after the lake shrinking caused by climate drought. In addition, the glacier meltwater may provide the necessary conditions for vegetation growth, and then, the vegetation development has provided the guarantee for the development of nebkhas around the salt lakes in the Qaidam Basin.
Key words:nebkhas/
chronology/
provenance/
environmental implication/
Qaidam Basin



PDF全文下载地址:

http://www.dsjyj.com.cn/data/article/export-pdf?id=dsjyj_11479