摘要
黄河贯通时间一直是地学研究者关注的热点问题,但未能形成共识。本文在阐明新近纪以来黄河中游及邻区古湖消亡及水系贯通过程的基础上,剖析了运用碎屑锆石U-Pb年龄谱物源示踪技术约束黄河贯通时间4个案例研究所存在的问题。三门湖泥岩中的钙结核和钙质层表明,0.3 Ma前该湖为咸水-半咸水内流湖,三门峡一带的黄河沿岸阶地是古湖的湖滨或河流阶地,三门湖沉积物源于当地河流,黄河上游与中游贯通发生于1.3 Ma~1.5 Ma,和~5 Ma前的结论不能成立。华北平原现黄河入海口附近钻孔沉积物源于燕山和太行山的河流,根据碎屑锆石U-Pb年龄谱得出的1.5 Ma~1.6 Ma黄河贯通的结论不成立。黄土是黄河泥沙的主要来源,黄土中碎屑锆石U-Pb年龄谱比较复杂,增加了运用这一技术约束黄河贯通时间的不确定性。
Although the cutting-through period of the Yellow River of China has always been a hot issue for geoscience researchers,no consensus had been reached.In this study,we elucidated the extinction of ancient lakes and the penetrating process of the middle reaches of the Yellow River and its adjacent areas since Neogene;then the issues in four case studies was picked up for examination of the use of tracing technology of U-Pb detrital zircon geochronology,which were used in four case studies for rebuilding the cutting-through period of the Yellow River in the middle reach.As reported in the referred case studies,there were calcium nodules and calcareous layers to be formed in the mudstone of the Sanmen Lake,indicating it is an endorheic lake of saltwater-brackish water before 0.3 Ma;the terraces along the Yellow River in the Sanmen Gorges were lakeside of the ancient lake or river terraces.Therefore,the sediments of the Sanmen lake originated from local rivers other than the later Yellow River.The conclusion that the Yellow River united the upper reaches with the middle reaches occurred at 1.3 Ma~1.5 Ma or~5 Ma cannot be established.Also as justified in the aforesaid cases,the borehole sediments near the present mouth of the Yellow River in the North China Plain originated from the rivers of the Yanshan Mountains as well as the Taihang Mountains;consequently,the advocated conclusion that the Yellow River run through in the upper and middle reach at 1.5 Ma~1.6 Ma in terms of the U-Pb age spectrum of detrital zircons is not convincing.In conclusion,loess is primary source of sediments in the Yellow River.The age spectrum of U-Pb detrital zircon in loess is too complicated for application,which increases the uncertainty about using U-Pb detrital zircon age spectrum to determine the period of channel connection of the Yellow River.
作者
张信宝
代彬
ZHANG Xinbao;DAI Bin(Key Laboratory of Mountain Environment Evolution and Regulation,Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Chengdu 610041,China;State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China;Puding Karst Ecosystem Observation Research Station,Chinese Academy of Sciences,Puding 562100,Guizhou,China)
出处
《山地学报》
CSCD
北大核心
2022年第5期637-647,共11页
Mountain Research
基金
国家自然科学基金(91747207)。
关键词
碎屑锆石U-Pb年龄谱
物源示踪技术
黄河
U-Pb detrital zircon geochronology
tracing technology
the Yellow River
