The role of weathering in the formation of bedrock valleys on Earth and Mars: A numerical modeling investigation
The role of weathering in the formation of bedrock valleys on Earth and Mars: A numerical modeling investigation
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风化在地球和火星基岩山谷形成中的作用：数值模拟研究
DOI：
10.1029/2011je003821
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发表时间：
2011
影响因子：
--
通讯作者：
V. Baker
中科院分区：
文献类型：
--
作者：
J. Pelletier;V. Baker
[1]基岩河谷发育的数值模型一般不明确地包括风化作用。然而，风化作用是一个重要的过程，它与通过渗流和径流运输松散的碎屑一起形成许多基岩山谷。在这里，我们提出了一个数值模型基岩山谷的发展，明确区分风化和运输松散的碎片，并能够形成类似于在自然界中观察到的基岩山谷。在该模型中，风化率被假定为随着水的可用性增加而增加，数据表明这种关系可能适用于许多水资源有限的环境。我们比较和对比的情况下，风化是径流引起的渗透与情况下，它是渗流或地下驱动流的结果的模型结果。我们的模型的表面流驱动的版本代表了一种替代流功率模型，明确显示了如何风化率和松散的碎片运输有关的地形或水流。地下流动驱动的版本，我们的模型可以解决分析使用线性Boussinesq近似。在这种情况下，该模型预测的剧院为首的山谷是抛物线的平面形状，预测大致一致的观察到的形状剧院为首的基岩山谷在火星上已被归因于渗流风化和偶发性的去除风化碎屑的径流，渗流，和/或泉水排放的组合。
[1] Numerical models of bedrock valley development generally do not include weathering explicitly. Nevertheless, weathering is an essential process that acts in concert with the transport of loose debris by seepage and runoff to form many bedrock valleys. Here we propose a numerical model for bedrock valley development that explicitly distinguishes weathering and the transport of loose debris and is capable of forming bedrock valleys similar to those observed in nature. In the model, weathering rates are assumed to increase with increasing water availability, a relationship that data suggest likely applies in many water-limited environments. We compare and contrast the model results for cases in which weathering is the result of runoff-induced infiltration versus cases in which it is the result of seepage- or subsurface-driven flow. The surface flow–driven version of our model represents an alternative to the stream-power model that explicitly shows how rates of both weathering and the transport of loose debris are related to topography or water flow. The subsurface flow–driven version of our model can be solved analytically using the linearized Boussinesq approximation. In such cases the model predicts theater-headed valleys that are parabolic in planform, a prediction broadly consistent with the observed shapes of theater-headed bedrock valleys on Mars that have been attributed to a combination of seepage weathering and episodic removal of weathered debris by runoff, seepage, and/or spring discharge.