Climate change and tectonic activity through erosion control Earth’s topography, much of which is shaped by river incision. The Yarlung River has dissected the Indian-Asian Collision Zone, and is one of the Earth’s largest rivers. However, its erosion rate history and how it interacts with regional tectonics remain ambiguous. Here, we apply low-temperature thermochronometry and thermal-kinematic models for bedrock samples from the Yarlung River. Our analysis reveals two stages of relatively fast exhumation occurred in different parts of the middle reach of the Yarlung River followed by remarkedly slow exhumation rate. First, a mid-Miocene period (15–9 Ma) of rapid exhumation occurred along much of the Yarlung River, including within wide portions of the valley and its tributaries. This period of rapid exhumation coincides with the stage of high precipitation rates recorded in the Asian marginal basins and the timing of the east-west extensional faults. In combination with extensional faults, the enhanced precipitation due to the onset of Asian monsoon would increase river discharge and thus accelerate mid-Miocene exhumation rates. Second, a Pliocene-Pleistocene (5–2 Ma) period of accelerated exhumation limited to gorges occurred in response to north-south normal faulting, implying local tectonics as a first-order control. Our results highlight roles of climatic and tectonic processes in shaping fluvial topography and how these change with time.

中文翻译：

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中中新世以来藏南雅鲁藏布江中游两期加速剥露

通过侵蚀控制的气候变化和构造活动控制着地球的地形，其中大部分是由河流切口形成的。雅鲁藏布江分割了印亚碰撞带，是地球上最大的河流之一。然而，它的侵蚀率历史以及它如何与区域构造相互作用仍然不明确。在这里，我们对雅鲁藏布江的基岩样品应用低温热计时法和热运动学模型。我们的分析表明，雅鲁藏布江中游的不同地区发生了两个相对较快的剥落阶段，其次是显着缓慢的剥落速度。首先，沿雅鲁藏布江的大部分地区发生了中中新世时期（15-9 Ma）的快速挖掘，包括山谷及其支流的大部分地区。这一快速剥露时期与亚洲边缘盆地记录的高降水率阶段和东西伸展断层的时间相吻合。与伸展断层相结合，由于亚洲季风的爆发而增加的降水将增加河流流量，从而加速中中新世的折返率。其次，上新世-更新世（5-2 Ma）加速折返期仅限于峡谷，以响应南北正断层，这意味着局部构造是一级控制。我们的研究结果突出了气候和构造过程在塑造河流地形方面的作用以及它们如何随时间变化。由于亚洲季风的到来而增加的降水将增加河流流量，从而加速中中新世的折返率。其次，上新世-更新世（5-2 Ma）加速折返期仅限于峡谷，以响应南北正断层，这意味着局部构造是一级控制。我们的研究结果突出了气候和构造过程在塑造河流地形方面的作用以及它们如何随时间变化。由于亚洲季风的到来而增加的降水将增加河流流量，从而加速中中新世的折返率。其次，上新世-更新世（5-2 Ma）加速折返期仅限于峡谷，以响应南北正断层，这意味着局部构造是一级控制。我们的研究结果突出了气候和构造过程在塑造河流地形方面的作用以及它们如何随时间变化。