青藏高原东南缘金沙江下游新生代构造与地貌演化  

Cenozoic tectonics and geomorphic evolution of the lower Jinsha River on the southeastern margin of the Tibetan Plateau

作　　者：王岸[1,2] 王国灿[1,2] 王团乐 施炎 魏杰 李皓若 吕甘雨 WANG An;WANG Guocan;WANG Tuanle;SHI Yan;WEI Jie;LI Haoruo;LYU Ganyu(Hubei Key Laboratory of Critical Zone Evolution,China University of Geosciences(Wuhan),Wuhan 430074,Hubei,China;School of Earth Sciences,China University of Geosciences(Wuhan),Wuhan 430074,Hubei,China;Three Gorges Geotechnical Consultants Co.,Ltd.,Wuhan 430074,Hubei,China)

机构地区：[1]中国地质大学(武汉)流域关键带演化湖北省重点实验室,湖北武汉430074 [2]中国地质大学(武汉)地球科学学院,湖北武汉430074 [3]长江三峡勘测研究院有限公司(武汉),湖北武汉430074

出　　处：《地质力学学报》2023年第4期453-464,共12页Journal of Geomechanics

基　　金：国家自然科学基金项目(41972223,41672195)。

摘　　要：青藏高原东南缘发育数十万平方千米的广阔地貌过渡带与大面积低起伏地貌面,独特的地貌提供了解读高原构造拓展与地表隆升时间、过程以及机制的理想窗口。为揭示青藏高原东南缘新生代构造变形响应和地貌演化过程,通过构造解析、构造地貌以及低温热年代学数据分析对金沙江下游流域进行综合研究。结果表明青藏高原东南缘早在始新世即已处于北西向为主的区域性挤压条件下而发生广泛褶皱变形。尽管始新世存在区域性变形响应,但青藏高原东南缘金沙江下游地区在古近纪为低海拔丘陵地貌,地表隆升幅度极为有限。晚渐新世—早中新世研究区总体处于长期的低剥蚀速率环境,促进了低海拔平缓地貌的形成。晚新近纪以来,青藏高原东南缘发生区域性缩短变形与显著地表隆升,大型水系同步下蚀,共同塑造形成现今较高海拔的低起伏地貌面与深切峡谷并存的特征性地貌。研究结果支持青藏高原东南缘晚新近纪以来的隆升与地壳构造缩短及增厚密切相关,而中下地壳塑性流动增厚机制并非必不可少。The southeastern margin of the Tibetan Plateau is distinguished by a vast transition zone with hundreds of thousands of square kilometers of low-relief surfaces,which provides an ideal window for unraveling the timing,process,and mechanisms of the tectonic propagation and surface uplift.In order to reveal the Cenozoic tectonic response and geomorphic evolution of the southeastern margin of the Tibetan Plateau,a comprehensive study in the lower Jinsha River was conducted with a tectonic investigation,tectonic-landform and low-temperature thermochronological data analysis.The results show that the southeastern margin of the Tibetan Plateau remained in NW-shortening as early as the Eocene,forming widespread folds.However,we suggest that in the Paleogene,the lower Jinsha River of the southeastern margin of the Tibetan Plateau was marked by a low hilly topography with rather limited surface uplift.In the Late Oligocene-Early Miocene,the study area was characterized by a long-term stage with low denudation rates,which promoted the formation of widespread low-relief surfaces.Since the late Neogene,the southeastern margin of the Tibetan Plateau has undergone regional shortening deformation and significant surface uplift with a simultaneous incision along large rivers,forming the present landforms characterized by high-elevation low-relief surfaces and deep gorges.The late Neogene surface uplift across the southeastern margin of the Tibetan Plateau is suggested to be closely related to the shortening deformation and associated crustal thickening.In contrast,the mid-lower crustal thickening by channel flow might not be indispensable.

关 键 词：青藏高原东南缘 构造解析 热年代学 构造地貌 裂变径迹 

分 类 号：P542[天文地球—构造地质学]