摘要
中国黄土高原上广泛分布着连续的第四系风成沉积,是研究亚洲干旱化过程、大气环流模式和亚洲季风演化的关键地区。目前对风成沉积的来源还存在很大争议,其中柴达木盆地是否为黄土高原提供大量碎屑物质是争议的焦点之一。文章利用沉积物厚度、孔隙度-深度关系和剥蚀速率等参数,定量估算得出柴达木盆地内第四系碎屑骨架体积为约(6.2±1.2)×10^(4) km^(3),而物源区可提供的碎屑骨架体积最大为约(6.4±0.8)×10^(4) km^(3),二者近似平衡。结果表明,柴达木盆地在第四纪时没有多余的碎屑可供外输,从物质守恒的角度揭示柴达木盆地无法为黄土高原提供大量碎屑。受东部鄂拉山的阻挡以及风蚀颗粒相对较大等因素的影响,第四纪风蚀作用产生的大量碎屑被就近搬运至盆地东部沉积下来。
Chinese Loess Plateau(CLP) widely preserves continuous Quaternary aeolian sediments,and is the key region for studying the Asian aridification process,atmospheric circulation patterns,and Asian monsoon evolution.At present,the provenance of these aeolian sediments remains disputed,and whether the Qaidam Basin,which has an area of 12×10^(4)km^(3) and is the largest sedimentary basin within the Tibetan Plateau to the west of the CLP,has been the major dust supplier to the CLP in the Quaternary is one of the focuses of the controversy.We herein quantitatively investigated the source-to-sink relationship between the Qaidam Basin and the CLP from the perspective of mass balance.Specifically,we estimate the grain volume of the Quaternary deposits as approximately(6.2±1.2)×10^(4)km^(3),by using the available isopach map of the Quaternary deposits preserved within the Qaidam Basin and the porosity-depth relationship revealed by borehole logging.For comparison,we also calculated the maximum grain volume provided by denudation zone in surrounding mountains and within the basin during the Quaternary as(6.4±0.8)×10^(4)km^(3),by multiplying the area of denudation zone extracted from DEM data,the published erosion rates and the duration time.The two estimates are approximately balanced,suggesting that there were no excess clastics to be transported outside the Qaidam Basin in the Quaternary.Our finding reveals that,whilst the western Qaidam Basin has experienced intense wind erosion in the Quaternary,it is unlikely the major source of the CLP.The wind-eroded materials were possibly transported to the eastern Qaidam Basin and deposited nearby,possibly resulting from the obstruction of the high Ela Shan to the east,and the relatively large grain size of the detritus that facilitates saltation rather than long-distance suspension.
作者
吴磊
胡晓燚
WU Lei;HU Xiaoyi(School of Earth Sciences,Zhejiang University,Hangzhou 310027,Zhejiang)
出处
《第四纪研究》
CAS
CSCD
北大核心
2022年第4期939-947,共9页
Quaternary Sciences
基金
国家自然科学基金项目(批准号:41972218)
中央高校基本科研业务费专项项目(批准号:2016QNA3013)共同资助。
关键词
物质守恒
碎屑骨架体积
柴达木盆地
黄土高原
源汇分析
mass conservation
detritus grain volume
Qaidam Basin
Chinese Loess Plateau
source-to-sink analysis
