青藏高原亚东-谷露裂谷带的隆升剥蚀对雅鲁藏布江河流演化的影响

The Yarlung Zangbo River is thousands of kilometers from east to west. There are differences in the structure, lithology and landforms along the river. The differences in the horizontal and vertical directions of different river sections have an important impact on the formation and development of the river. However, there are few studies on the low -temperature thermochronology about different structures or geomorphology background river section. The Yarlung Zangbo River develops the abundance of large knickpoints, which in many cases coincide with north–south trending rifts. Among them, the geological and geomorphological features of the knickpoints at the intersection of the Yadong-Gulu Rift Belt and the Yarlung Zangbo River are particularly prominent. This project intends to study the exhumation about the upper wall and footwall of the Yadong-Gulu Rift normal fault (the knickpoint between the Renbu-Qushui) and the granite body away from the knickpoint in the east. Collecting three low-temperature thermochronology age-elevation profiles at the upper wall and footwall of the Yadong-Gulu Rift and the granite body away from the knickpoint. The zircon and apatite (U-Th)/He data and thermal history simulation method were used to reveal exhumation of the upper wall and footwall of the Yadong-Gulu Rift and the granite body away from the knickpoint. The uplifting and exhumation history of the rift zone is compared with that away from the rift. The model relationship between the knickpoint and the north-south normal fault will be established. Finally, we explore the history and control factors of the uplift and exhumation of the different landforms or tectonic backgrounds of the Yarlung Zangbo River.

雅鲁藏布江东西向长达数千公里，流域内构造、岩性和地貌存在差异，不同河段在水平和垂直方向差异性变化对流域地貌的形成和发育有重要的影响，然而不同构造或地貌背景河段的低温热年代学对比性研究较少。雅鲁藏布江发育多个河流裂点，大多数河流裂点位于青藏南北向裂谷带与雅鲁藏布江相交处，其中亚东-谷露裂谷带与雅鲁藏布江相交处河流裂点地质和地貌特征尤为突出。本项目拟以亚东-谷露裂谷正断层上、下盘（即仁布-曲水之间的河流裂点位置）和以东远离裂点位置河谷北侧的花岗岩体为研究对象，正断层上、下盘和远离河流裂点位置的河谷内分别采集低温热年代学年龄-高程剖面，利用锆石和磷灰石(U-Th)/He数据和热历史模拟方法揭示河谷内南北向裂谷带正断层上、下盘和远离裂谷带河道的隆升剥蚀历史，对比不同河段的隆升剥蚀差异，建立河流裂点与南北向正断裂之间的模型关系，探究雅鲁藏布江不同地貌或构造背景河段隆升剥蚀历史和控制因素。

雅鲁藏布江东西向长达数千公里，流域内构造、岩性和地貌存在差异，不同河段在水平和垂直方向差异性变化对流域地貌的形成和发育有重要的影响，然而不同构造或地貌背景河段的低温热年代学对比性研究较少。本项目以亚东-谷露裂谷正断层上、下盘（即仁布-曲水之间的河流裂点位置)和以东远离裂点位置河谷北侧的花岗岩体为研究对象，采集低温热年代学年龄-高程剖面，利用锆石和磷灰石(U-Th)/He数据和Glide数值模拟，揭示了早中新世以来雅鲁藏布江宽谷段河谷保持相对稳定的剥蚀历史，而河谷与亚东-谷露裂谷段交汇处自15-10 Ma剥蚀速率开始增强，表明亚东-谷露裂谷开始活动时间介于15-10 Ma之间，而裂谷的发育影响了河流上游相对基准面，造成上游主河道剥蚀减弱，河流侧向侵蚀增强进而形成宽谷河道，现今窄谷和宽谷的河流地貌形态主要受控于亚东-谷露裂谷的发育。