COLLABORATIVE RESEARCH: Calibration of Late Cenozoic Incision, Uplift, and Erosion Along the Indus River, Northern Pakistan

了解高山地形在许多山脉的演变是一个尚未解决的问题。像喜马拉雅西北部这样的地区为研究地形演变提供了一个特别有趣的地点，因为它的特点是快速的第四纪剥蚀，差异隆起，河流显示出一些世界上最高的梯度和最大的沉积物负荷，广泛的气候制度，活跃的构造运动，以及极端的地形起伏。在缺乏对剥蚀率、基岩隆起率和地表隆起率的了解的情况下，地形发展的重建或模型被迫依赖于关于这些因素的绝对幅度和相对重要性的未经检验的假设。然而，在喜马拉雅西北部和喀喇昆仑，似乎有可能将数字高程数据集与关于切口、侵蚀和隆起的时间和大小的年代学和地貌数据结合起来，以便为这一动态区域的地形演变提供一个校准的视角。本研究的目的是确定喜马拉雅造山带这一部分的切口和基岩冷却的时间和速率；对区域剥蚀进行体积近似，重建印度河沿岸的基准面变化；重建构造产生的局部隆升、区域隆升（构造或均衡）与侵蚀剥蚀之间的相互作用。将使用的方法包括：使用宇宙核素对稻草表面进行暴露年龄测年；用多矿物定年法研究垂直地形剖面的冷却时代基于时间和几何约束的河流剖面重建以及基于喜马拉雅西北部数字高程数据集的坡度、高度分布、梯度和体积分析。

Understanding of the evolution of alpine topography in many mountain chains represents an unresolved problem. A region like the northwestern Himalaya provides a particularly intriguing site for the study of evolving topography, because it is characterized by rapid Quaternary denudation, differential uplift, rivers showing some of the highest gradients and largest sediments loads in the world, a breadth of climatic regimes, active tectonicsm, and extreme topographic relief. In the absence of knowledge of rates of denudation, bedrock uplift, and surface uplift, reconstructions or models of topographic development are forced to rely on untested assumptions concerning the absolute magnitude and relative importance of each of these factors. In the northwestern Himalaya and Karakoram, it appears possible however, to combine digital elevation data sets with chronologic and geomorphic data on timing and magnitude of incision, erosion, and uplift in order to provide a calibrated perspective on topographic evolution of this dynamic region. The goals of this study are to define the timing and rates of incision and bedrock cooling in this part of the Himalayan orogen; to make volumetric approximations of regional denudation, reconstruct base- level changes along this part of the Indus River; and to reconstruct the interactions among tectonically generated localized uplift, regional uplift (tectonic or isostatic), and erosion and denudation. The approaches that will be used include: exposure-age dating of strath surfaces using cosmogenic nuclides; development of cooling ages histories using multi-mineral dating of vertical relief sections; reconstruction of river profiles based on temporal and geometric constraints; and analysis of slopes, altitudinal distributions, gradients, and volumes based on digital elevation data set for the NW Himalaya.