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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Erosion of an active fault scarp leads to drainage capture in the Amazon region, Brazil
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Erosion of an active fault scarp leads to drainage capture in the Amazon region, Brazil

机译：活动断层陡坡的侵蚀导致巴西亚马逊地区的排水被捕获

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Far from the continental margin, drainage basins in Central Amazonia should be in topographic steady state; but they are not. Abandoned remnant fluvial valleys up to hundreds of square kilometers in size are observed throughout Amazonia, and are evidence of significant landscape reorganization. While major Late Miocene drainage shifts occurred due to initiation of the transcontinental Amazon River, local landscape change has remained active until today. Driven either by dynamic topography, tectonism, and/or climatic fluctuations, drainage captures in Amazonia provide a natural experiment for assessing the geomorphic response of lowslope basins to sudden, capture related base-level falls. This paper evaluates the timing of geomorphic change by examining a drainage capture event across the Baependi fault scarp involving the Cuieiras and Tarum?-Mirim River basins northwest of the city of Manaus in Brazil. A system of capture-related knickpoints was generated by base-level fall following drainage capture; through numerical modeling of their initiation and propagation, the capture event is inferred to have occurred between the middle and late Pleistocene, consistent with other studies of landscape change in surrounding areas. In low-slope settings like the Amazon River basin, base-level fall can increase erosion rates by more than an order of magnitude, and moderate to large river basins can respond to episodes of base-level fall over timescales of tens to hundreds of thousands of years.
机译：中亚马孙地区的流域应远离大陆边缘，应处于地形稳定状态。但事实并非如此。在整个亚马逊河地区，观察到了高达数百平方公里的废弃河谷谷，它们是景观重组的证据。尽管由于跨大陆亚马逊河的启动而发生了中新世晚期的主要排水变化，但直到今天，当地的景观变化一直很活跃。在动态地形，构造和/或气候波动的驱动下，亚马逊地区的排水捕获为评估低坡度盆地对突然的，捕获的相关基准面下降的地貌响应提供了自然的实验。本文通过检查横跨巴西马瑙斯市西北部Cuieiras和Tarum？-Mirim河盆地的Baependi断层陡坡的排水捕获事件，评估了地貌变化的时间。排水系统捕获后，由于基层下降而产生了与捕获有关的拐点系统;通过对其萌生和传播的数值模拟，推断捕获事件发生在中更新世晚期和后期，这与周围地区景观变化的其他研究一致。在像亚马逊河流域这样的低坡度地区，基准面的下降会使侵蚀率增加一个数量级以上，中度到大型河流盆地可以在数万至数十万的时间范围内对基准面的下降事件做出反应。年。

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