Exhumation and topographic evolution of the Namche Barwa Syntaxis, eastern Himalaya
Exhumation and topographic evolution of the Namche Barwa Syntaxis, eastern Himalaya
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DOI：
10.1016/j.tecto.2017.10.026
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发表时间：
2018-01
期刊：
影响因子：
2.9
通讯作者：
Rong Yang;F. Herman;M. Fellin;C. Maden
中科院分区：
文献类型：
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作者：
Rong Yang;F. Herman;M. Fellin;C. Maden
南迦巴瓦构造结作为构造活动最活跃的地区之一，仍然是探索构造、地表过程和景观演化之间关系的合适场所。对该构造结的形成和演化，提出了构造动脉瘤模型和构造结扩张模型。在这里，我们使用一个多学科的方法，低温热年代学，数值模拟，河流剖面和地形分析的基础上，研究构造，侵蚀和景观演变之间的相互作用，并测试这些模型。我们的结果强调了年轻冷却年龄的存在（即，<1Ma），沿着Parlung河，在构造结以北。使用数值模拟，我们认为，最近的挖掘率的增加，需要暴露这些年轻的年龄。我们的河流分析揭示了空间变化的渠道陡度，我们解释，以反映岩石隆起模式。通过建立侵蚀速率和地形特征之间的关系，我们发现侵蚀速率与地形特征的相关性很差，这表明景观仍在不断发展。总之，这些结果似乎更好地解释了一个机制，涉及向北扩展的结，这导致高岩石隆起率以北的结和一个过渡状态的地形调整不断变化的构造环境。
The Namche Barwa Syntaxis, as one of the most tectonically active regions, remains an appropriate place to explore the relationship between tectonics, surface processes, and landscape evolution. Two leading models have been proposed for the formation and evolution of this syntaxis, including the tectonic aneurysm model and the syntaxis expansion model. Here we use a multi-disciplinary approach based on low-temperature thermochronometry, numerical modeling, river profile and topographic analyses to investigate the interactions between tectonics, erosion, and landscape evolution and to test these models. Our results emphasize the presence of young cooling ages (i.e., < 1 Ma) along the Parlung River, to the north of the syntaxis. Using numerical modeling we argue that a recent increase in exhumation rate is required to expose these young ages. Our river analysis reveals spatial variations in channel steepness, which we interpret to reflect the rock uplift pattern. By establishing the relationship between erosion rates and topographic features, we find that erosion rates are poorly to weakly correlated with topographic features, suggesting that the landscape is still evolving. Altogether, these results seem better explained by a mechanism that involves a northward expansion of the syntaxis, which causes high rock uplift rates to the north of the syntaxis and a transient state of topography adjusting to an evolving tectonic setting.