Stratigraphic control of landscape response to base-level fall, Young Womans Creek, Pennsylvania, USA
Stratigraphic control of landscape response to base-level fall, Young Womans Creek, Pennsylvania, USA
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美国宾夕法尼亚州 Young Womans Creek 景观对基准面下降响应的地层控制
DOI：
10.1016/j.epsl.2018.10.005
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发表时间：
2018
影响因子：
5.3
通讯作者：
Hidy, Alan J.
中科院分区：
文献类型：
--
作者：
DiBiase, Roman A.;Denn, Alison R.;Bierman, Paul R.;Kirby, Eric;West, Nicole;Hidy, Alan J.
景观被认为是通过一个边界的上游传播来响应相对基准面的变化，这个边界描绘了地形调整后的遗迹。然而，岩石强度的空间变化会影响这种瞬态景观的地形表现，特别是在层状岩石中，强度变化可以掩盖由于气候或构造变化而预期的地形信号。在这里，我们分析了美国阿巴拉契亚高原上一个220公里的集水区Young Womans Creek对基准面下降的景观响应。我们测量了来自17个嵌套流域的河流砂中的be浓度，并使用沉积物和be生产的空间分布模型来限制从集水口向上游传播的基准面下降速率增加三倍的情况。利用激光雷达地形和附近的详细地层剖面，我们绘制了连续的、块状的、耐腐蚀的砂岩地层的范围，这些砂岩层作为盖层覆盖在更容易被侵蚀的砂岩和粉砂岩上。盖层以两种方式影响景观响应。首先，它是缓慢侵蚀（11.5 m Myr−1）、低坡度（3-5°）的残余地形区域与适应基准面下降的更低、更陡峭的景观部分之间的边界。其次，尽管侵蚀速率（36 m Myr−1）和基岩基质相似，但由上覆盖层支撑的山坡被粗沉积物包裹，比盖层被侵蚀的山坡（10°）陡峭得多（20-30°）。我们的研究结果说明了缓慢倾斜的层状岩石如何在岩性、地形和侵蚀速率之间产生复杂的关系，突出了理解岩石材料性质如何影响地表过程和景观演化的重要性。
Landscapes are thought to respond to changes in relative base level through the upstream propagation of a boundary that delineates relict from adjusting topography. However, spatially-variable rock strength can influence the topographic expression of such transient landscapes, especially in layered rocks, where strength variations can mask topographic signals expected due to changes in climate or tectonics. Here, we analyze the landscape response to base-level fall in Young Womans Creek, a 220 km2catchment on the Appalachian Plateau, USA underlain by gently folded Paleozoic sedimentary rocks. We measuredin situ10Be concentrations in stream sands from 17 nested watersheds, and used a spatially-distributed model of sediment and10Be production to constrain a threefold increase in the rate of base-level fall propagating upstream from the catchment outlet. Using lidar topography and a nearby detailed stratigraphic section, we map the extent of continuous, blocky, resistant sandstone strata that act as a caprock overlying more easily erodible sandstones and siltstones. The caprock influences landscape response in two ways. First, it serves as a boundary between slowly eroding (11.5 m Myr−1), low-sloping (3–5°) areas of relict topography and lower, steeper portions of the landscape adjusting to base-level fall. Second, hillslopes supported by the overlying caprock are armored with coarse sediment and are significantly steeper (20–30°) than hillslopes where the caprock has been eroded (10°), despite having similar erosion rates (36 m Myr−1) and bedrock substrate. Our results illustrate how gently dipping, layered rocks engender complicated relationships between lithology, topography and erosion rate, highlighting the importance of understanding how rock material properties influence surface processes and landscape evolution.
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影响因子：
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作者：
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影响因子：
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发表时间：
2016-08
期刊：
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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DOI：
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发表时间：
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期刊：
影响因子：
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作者：
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