Collaborative Research: What Created the Southern Tibetan Plateau Drainage Divide? Integrated Tectonic and Geomorphic Investigation of the Gangdese Range and Yarlung River

合作研究：是什么造成了青藏高原南部的排水分水岭？

基本信息

批准号：
1917695
负责人：
Adam Forte
金额：
$ 26.36万
依托单位：
Louisiana State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-09-01 至 2024-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1917695&HistoricalAwards=false
关键词：
Collaborative Research What Created Southern

项目摘要

Collisional motions between tectonic plates deform the Earth's crust, forming mountain belts over millions of years. This process is most visible along the boundaries between tectonic plates, but also occurs further away from plate boundaries, where more subtle features reflect deeper-seated tectonic movements. This project focuses on the Gangdese Mountains in southern Tibet, which host some of the highest mountains of the Tibetan Plateau. These mountains are located 200 kilometers north of the high peaks of the Himalayas, but are actively rising due to deep-seated faulting related to collision between the Indian and Asian tectonic plates. This range forms the boundary between the low-relief, relatively flat interior of the Tibetan Plateau that retains all precipitation in lakes, and the higher-relief region to the south that is drained by the Yarlung-Siang-Brahmaputra river. By mapping the geologic structures, determining when and at what rate rocks were exposed at the surface, and comparing these data to simulations of erosion due to precipitation and river incision, the project investigators will determine the details of the deep-seated tectonic motions and how these motions affected the landscape of the Tibetan Plateau and one of the largest river systems in Asia. Broader impacts of this project will include the development of teaching modules based on this research, the preparation of three PhD students and one postdoctoral researcher to join the skilled scientific workforce, and outreach to the public through museum-hosted instructional modules and public research presentations. This research seeks to understand how and to what extent Miocene to Recent tectonics affected the landscape and river systems of the southern Tibetan Plateau. The project will test the hypothesis that a major crustal ramp or duplex beneath the Gangdese Mountains drove rock uplift along the southern boundary of the Plateau, in the interior of the Himalayan orogenic belt, since at least Miocene time. Research will focus on whether rock uplift outpaced erosion and established the drainage divide that currently separates the expansive internally-drained region from the Yarlung-Siang-Brahmaputra river system to the south. To address this hypothesis and other alternative hypotheses, the researchers will conduct an integrated study involving field-focused structural geology, thermochronology, landscape evolution modeling, and detrital cosmogenic radionuclide dating. The hypotheses provide a set of testable predictions for the geometry of rock exposures and the history of deformation, timing and rates of rock cooling, expected landscape evolution in response to various tectonic and/or climatic drivers, and millennial-scale erosion rates for catchment basins. If a tectonic driver for establishment of the southern drainage boundary is supported by the data, then tectonics is also implicated in the evolution of the Yarlung-Siang-Brahmaputra River system, one of the largest in the world. This research will advance our collective understanding of how mountain belts and plateaus form in response to tectonics, how mountain landscapes evolve and respond to variable tectonic influences, and how major river systems develop during million-year to millennial timescales.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

构造板块之间的碰撞运动使地壳变形，在数百万年的时间里形成了山脉。这一过程在构造板块之间的边界上最为明显，但也发生在远离板块边界的地方，那里更微妙的特征反映了更深层次的构造运动。该项目重点关注西藏南部的冈底斯山脉，这里拥有青藏高原的一些最高山脉。这些山脉位于喜马拉雅山主峰以北 200 公里处，但由于印度和亚洲板块碰撞引起的深部断层，正在积极上升。该山脉形成了青藏高原低地势、相对平坦的内部地区（将所有降水保留在湖泊中）和南部高地势地区（雅鲁藏布江流域）之间的边界。通过绘制地质结构图，确定岩石暴露在地表的时间和速率，并将这些数据与降水和河流切割造成的侵蚀模拟进行比较，项目研究人员将确定深层构造运动的细节以及如何这些运动影响了青藏高原的地貌和亚洲最大的河流系统之一。该项目的更广泛影响将包括开发基于该研究的教学模块、培养三名博士生和一名博士后研究员加入熟练的科学队伍，以及通过博物馆主办的教学模块和公共研究演示向公众进行推广。这项研究旨在了解中新世至近代构造如何以及在何种程度上影响青藏高原南部的景观和河流系统。该项目将验证以下假设：至少自中新世以来，冈底斯山脉下方的一个主要地壳坡道或复式体沿着喜马拉雅造山带内部的高原南部边界驱动岩石隆起。研究将集中于岩石隆升速度是否超过了侵蚀速度，并确定了目前将广阔的内排水地区与南部的雅鲁藏布江-雅鲁藏布江水系分开的排水分界线。为了解决这一假设和其他替代假设，研究人员将进行一项综合研究，涉及现场结构地质学、热年代学、景观演化模型和碎屑宇宙成因放射性核素测年。这些假设为岩石暴露的几何形状和变形历史、岩石冷却的时间和速率、响应各种构造和/或气候驱动因素的预期景观演化以及集水盆地的千年规模侵蚀率提供了一组可测试的预测。。如果数据支持建立南部流域边界的构造驱动因素，那么构造也与世界上最大的河流之一雅鲁藏布江-雅鲁藏布江-雅鲁藏布江水系的演化有关。这项研究将增进我们对山地带和高原如何响应构造运动而形成、山地景观如何演化和响应可变构造影响以及主要河流系统如何在数百万年到千年时间尺度内发展的集体理解。该奖项反映了 NSF 的法定使命通过使用基金会的智力价值和更广泛的影响审查标准进行评估，并被认为值得支持。