The Importance of Hillslope Scale in Responses of Chemical Erosion Rate to Changes in Tectonics and Climate
The Importance of Hillslope Scale in Responses of Chemical Erosion Rate to Changes in Tectonics and Climate
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DOI：
10.1029/2020jf005562
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发表时间：
2020-09
期刊：
影响因子：
--
通讯作者：
K. Ferrier;J. Perron
中科院分区：
文献类型：
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作者：
K. Ferrier;J. Perron
化学侵蚀因其对地形、河流和土壤的养分供应、沉积物成分和地球气候的影响而受到广泛关注。虽然对化学侵蚀速率的控制已经在稳态模型中得到了广泛的研究，但很少有研究探索在对外部扰动的瞬时响应过程中对化学侵蚀速率的控制。在这里，我们开发了一个土壤-地貌、土壤厚度和土壤矿物学共同演化的数值模型，并用它来模拟岩石隆起、土壤生产、土壤运输和矿物溶解速率的阶跃变化。这些模拟表明，构造和气候扰动可以对土壤化学侵蚀速率产生不同速度、大小和空间格局的响应，气候和构造扰动可能会对坡面质量通量、土壤化学和沉积物组成产生不同的特征。化学侵蚀速率的响应时间主要受坡长控制，其次受岩石抬升速率、土壤生产速率、迁移速率和矿物溶解速率的影响。这种对排水密度的强烈依赖意味着，景观的化学侵蚀反应应取决于河流切割和土壤运输的相对效率，因此可能受到气候和生物因素的调节。模拟进一步表明，与河道剖面相比，坡面响应的时间尺度可能更长，这意味着化学侵蚀响应时间可能更多地受到坡面迟缓的限制，而不是通过河道剖面的信号传播速度的限制。
Chemical erosion is of wide interest due to its influence on topography, nutrient supply to streams and soils, sediment composition, and Earth's climate. While controls on chemical erosion rate have been studied extensively in steady‐state models, few studies have explored the controls on chemical erosion rate during transient responses to external perturbations. Here we develop a numerical model for the coevolution of soil‐mantled topography, soil thickness, and soil mineralogy, and we use it to simulate responses to step changes in rates of rock uplift, soil production, soil transport, and mineral dissolution. These simulations suggest that tectonic and climatic perturbations can generate responses in soil chemical erosion rate that differ in speed, magnitude, and spatial pattern and that climatic and tectonic perturbations may impart distinct signatures on hillslope mass fluxes, soil chemistry, and sediment composition. The response time of chemical erosion rate is dominantly controlled by hillslope length and is secondarily modulated by rates of rock uplift, soil production, transport, and mineral dissolution. This strong dependence on drainage density implies that a landscape's chemical erosion response should depend on the relative efficiencies of river incision and soil transport and thus may be mediated by climatic and biological factors. The simulations further suggest that the timescale of the hillslope response may be long relative to that of river channel profiles, implying that chemical erosion response times may be limited more by the sluggishness of the hillslopes than by the rate of signal propagation through river channel profiles.