古老的长江,年轻的三峡  

The Ancient Yangtze River versus the Young Three Gorges

作　　者：张信宝[1,2] 胡凯衡[1] 刘彧[2,3] 张启源 刘维明 王世杰[3] ZHANG Xinbao;HU Kaiheng;LIU Yu;ZHANG Qiyuan;LIU Weiming;WANG Shijie(Key Laboratory of Mountain Hazards and Earth Surface Process,Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Chengdu 610041,China;Puding Karst Ecosystem Research Station,Chinese Academy of Sciences,Puding 562100,Guizou,China;Institute of Geochemistry,Chinese Academy of Science,Guiyang 550081,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院、水利部成都山地灾害与环境研究所山地灾害与地表过程重点实验室,成都610041 [2]中国科学院普定喀斯特生态系统观测研究站,贵州普定562100 [3]中国科学院地球化学研究所环境地球化学国家重点实验室,贵阳550081 [4]中国科学院大学,北京100049

出　　处：《山地学报》2021年第5期611-620,共10页Mountain Research

基　　金：国家自然科学基金(91747207);第二次青藏高原综合科学考察研究专题项目(2019QZKK0902)。

摘　　要：长江的形成演化长期以来一直是地貌学界关注的热点。论文在构造—气候—地貌耦合体系的框架下,通过长江上游不同类型河流阶地空间分布格局的分析,推演新生代以来长江上游的水系演化过程。古近纪长江上游地区为断陷湖盆内流水系,长江尚未形成。古老的长江形成于新近纪,川江是古长江的上游,在乌江汇口涪陵附近南流,沿乌江—沅江—洞庭湖汇入长江中游河段。这一时期,金沙江南流入海,未东流汇入川江。三峡贯通大致发生于新近纪—第四纪之交(年轻的三峡),原沿乌江南流的川江被袭夺东流,四川盆地内的川江及支流下切,形成连续稳定分布的基座阶地。西部高原的南北向古水系被袭夺东流,横断山区的金沙江、大渡河和岷江等河流急遽下切,深切河谷内滑坡阻河溃决形成的堰塞湖阶地发育。金沙江等河流溯源侵蚀过程仍在继续,但尚未影响到裂点以上的青藏高原面上河段,这些河段河谷内的阶地为堆积或埋藏阶地。分布于珠江流域的盲鱼(Sinocyclocheilus sanxiaensis,~0.55 Ma)出现在秭归附近的长江和云南高原与川中丘陵紫色土酸碱度的差异(前者酸性,后者中性偏碱性),这两个证据也是“年轻的三峡”的佐证。The formation and evolution of the Yangtze River of China has long been a hot topic in geomorphology.In this study,it provided a speculation on water system evolution process of the Upper Yangtze River since Cenozoic Era based on a comparison of spatial distribution of different types of river terraces under a research context of tectonic-climatic-geomorphological coupling.In Paleogene Period,endorheic lakes had been developing in faulted lake basins in the areas of the upper reaches of the Yangtze River,and the Yangtze River had not been formed yet.The ancient Yangtze River was formed in Neogene Period,when the present Chuanjiang River(the Sichuan reach of the Yangtze River)was the headwater of the ancient Yangtze River,flowing southward near Fuling,the confluence of Wujiang River,and merging into the middle reaches of the Yangtze River along the Wujiang River-the Yuanjiang River-the Dongting Lake.During this period,the Jinsha River(a name for the upstream of Yangtze River starting from Yushu,Qinghai Province to Yibin city,Sichuan province,China)flowed into sea in the south but did not flow into the Chuanjiang River in the east.The penetration of Three Gorges to form a direct connection with the middle reaches of the Yangtze River occurred quite probably at the turn of Neogene and Quaternary(the young Three Gorges).During this period,the Chuanjiang River,which originally flowed along the south of Wujiang River,was seized and flowed eastward and the Chuanjiang River and its tributaries in Sichuan Basin incised downward the stable platform geology,forming a continuously and stably base terraces.As the ancient water system with north-south orientation in the western plateau was seized to flow eastward,and rivers in the Hengduan Mountains,such as the Jinsha River,the Daduhe River and the Minjiang River incised downward rapidly,the barrier lake(endorheic lakes,landslide dammed lakes,etc.)terraces were created extensively as consequences of fluvial incisions in deep valleys.Although the upstream erosion processes of t

关 键 词：古老的长江 年轻的三峡 金沙江 川江 堰塞湖阶地 基座阶地 

分 类 号：K928.42[历史地理—人文地理学]