长江的前世今生

发布时间：2018-08-06 10:23

【摘要】：长江是中华民族的母亲河,在中华文明历史进程和当代国计民生中占据独特的地位.长江是世界第三、亚洲第一大河,在区域宏观地理环境演化中具有标志性意义.长江的年龄(或者起源与演化历史)作为地球科学界和大众关注的热点,长期存在重大争议,从4 5百万年(始新世)到数万年(更新世晚期)不等,成为科学界一个著名的"世纪谜题".对青藏高原东南缘新生代盆地开展年代学与沉积学研究,揭示出在始新世时期区内存在大型的南流水系,在渐新世期间(或渐新世末期)南流水系转向东流,形成长江第一湾(也有写作"弯").长江中下游新生代盆地的沉积记录也显示,长江上游物质在渐新世晚期(或者最晚在渐新世/中新世之交)就已经能够到达下游,表明贯通东流的长江水系从此诞生.长江是超大型河系,其地质演化主要受到区域构造地貌控制.在新生代,青藏高原地区岩石圈加厚,地表隆升;亚洲东部岩石圈持续伸展减薄,西太平洋边缘海扩张,导致中国西高东低的宏观地形格局逐渐建立,长江的发育与演化正是孕育在这样的宏观构造地貌背景之下.
[Abstract]:The Yangtze River is the mother river of the Chinese nation and occupies a unique position in the historical process of Chinese civilization and the contemporary national economy and people's livelihood. Yangtze River is the third largest river in the world and the largest river in Asia. The age (or origin and evolution history) of the Yangtze River has long been the focus of attention of the Earth's scientific community and the public. It has long been a subject of great controversy, ranging from 45 million years (Eocene) to tens of thousands of years (late Pleistocene). It has become a famous puzzle of the century for the scientific community. The geochronology and sedimentology of Cenozoic basins in the southeastern margin of the Qinghai-Xizang Plateau have been studied. It is revealed that there were large southern flowing systems in the area during the Eocene, and the southern flow system turned eastward during the Oligocene (or the late Oligocene). Form the first bay of the Yangtze River. The sedimentary records of the Cenozoic basins in the middle and lower reaches of the Yangtze River also show that the material in the upper reaches of the Yangtze River reached the lower reaches in the late Oligocene (or at the latest between the Oligocene and the Miocene), indicating that the Yangtze River water system running eastward was born. The Yangtze River is a super-large river system, and its geological evolution is mainly controlled by regional tectonic landforms. In the Cenozoic, the lithosphere of the Qinghai-Tibet Plateau became thicker and the surface uplifted, and the lithosphere in eastern Asia continued to stretch and thin, and the marginal seas of the western Pacific Ocean expanded, which led to the gradual establishment of the macro-topographic pattern of the high and eastern lower in China. The development and evolution of the Yangtze River is conceived in such a macro-tectonic geomorphological background.
【作者单位】：云南大学资源环境与地球科学学院;中国科学院青藏高原地球科学卓越创新中心;南京大学地球科学与工程学院;南京师范大学地理科学学院;
【基金】：中国科学院战略性先导科技专项项目(编号:XDB03020301) 中国地质调查局大陆架科学钻探项目(编号:GZH201100202)资助
【分类号】：P343.1;P542

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