Relations between tectonics, climate and erosion in an active orogen: case study of the eastern Himalaya in Bhutan and India

大约55万年前，印度大陆和欧亚大陆之间的碰撞导致了喜马拉雅山脉的隆起，喜马拉雅山脉是地球上最大和最高的山脉带。这一范围形成了一个物理屏障，通过迫使来自印度洋的潮湿风沿着其南部壁垒凝结并带来暴雨，对气候产生了深远的影响。在较短的时间尺度（一年）内，这种被称为季风的现象通过引发山体滑坡和剧烈的洪水对人口产生影响。在地质时间尺度上（数千年到数百万年），季风影响着喜马拉雅山的侵蚀，改变了它的地形，使它成为世界海洋最重要的沉积物来源。重要的是，喜马拉雅的侵蚀历史通过岩石风化和海洋沉积物中的有机碳埋藏来调节大气中的二氧化碳水平，对全球气候变化产生了重大影响。山脉的侵蚀是岩石增生和变形（构造作用）与气候调节的地表作用复杂相互作用的结果。我的研究计划的目的是破译和量化这些相互关系。这一以喜马拉雅造山带为重点的基础科学问题最近被确定为当前构造学中四个最重要的研究课题之一。我将集中讨论东喜马拉雅造山带及其位于不丹和印度的前陆盆地的关键部分。我将采用多学科方法，包括野外测绘（识别岩石单元和结构）、热年代学（测量侵蚀）、稳定同位素地球化学、孢粉学、磁地层学（破译气候变化）和数值模拟，以研究过去1000万年气候和构造因素之间的动态关系及其对这座山景观演变的影响。对加拿大的好处包括在喜马拉雅研究的高调背景下为学生提供专业但多学科的培训，并进一步了解地球演化的过程，这将为有关地质灾害、环境保护和气候变化的政策制定举措提供信息。

The collision between the Indian and Eurasian continents about 55 Ma ago resulted in the uplift of the Himalaya, the largest and highest mountain belt on Earth. This range creates a physical barrier that has a profound effect on climate by forcing moist winds derived from the Indian Ocean to condense along its southern rampart and deliver heavy rainfalls. At short timescales (year), this phenomenon called the monsoon has impact on human populations by generating landslides and dramatic floods. At geological timescales (thousands to millions of years), the monsoon influences the erosion of the Himalaya, modifying its topography and making it the most important source of sediment input to the world's oceans. Importantly, the erosion history of the Himalaya has major consequences for global climate change by modulating CO2 levels in the atmosphere through rock weathering and organic carbon burial in the oceanic sediments. The erosion of the range results from the complex interactions between accretion and deformation of the rocks (tectonic processes) and climatically modulated surface processes. The purpose of my research program is to decipher and quantify these interrelations. This basic scientific issue with a special emphasis on the Himalayan orogen was recently identified as one of the four most important current research topics in tectonics. I will focus on key parts of the eastern Himalayan orogen and its foreland basin in Bhutan and India. I will adopt a multidisciplinary approach involving field mapping (to identify the rock units and the structures), thermochronology (to measure erosion), stable isotope geochemistry, palynology, magnetostratigraphy (to decipher climatic changes), and numerical modelling to investigate dynamic relations between climatic and tectonic factors and their impact on the landscape evolution of this mountain over the last 10 million years. Benefits for Canada include specialized yet multidisciplinary training to students in the high-profile context of Himalayan research, and further understanding of the processes responsible for the Earth's evolution that will inform into policy development initiatives regarding geohazard, environmental protection and climate change.