Steady state, erosional continuity, and the topography of landscapes developed in layered rocks
Steady state, erosional continuity, and the topography of landscapes developed in layered rocks
复制标题
稳态、侵蚀连续性以及层状岩石中发育的景观地形
DOI：
10.5194/esurf-5-85-2017
复制
发表时间：
2017
影响因子：
3.4
通讯作者：
J. Myre
中科院分区：
文献类型：
--
作者：
M. Perne;M. Covington;E. Thaler;J. Myre
摘要。地形稳态的概念极大地增进了我们对地貌、构造、气候和岩性之间关系的理解。在地形稳态下，各处的侵蚀速率相等，坡度会进行调整，以使不同强度岩石中的侵蚀速率相等。这个概念模型隐含了不同岩石类型之间垂直接触的假设。在此我们假设，层状岩石中的地貌将趋向于一种侵蚀连续性的状态，即接触面两侧在平行于接触面的方向上的后退速率相等，而非在垂直方向上。对于垂直接触，侵蚀连续性与地形稳态相同，而对于水平接触，它等同于岩石接触面两侧的水平后退速率相等。通过解析解和数值模拟，我们表明侵蚀连续性预测了在水平层状岩石模拟中形成的通量稳态地貌的形态。对于河流功率侵蚀，连续性稳态的性质取决于侵蚀模型中的指数n。当n = 1时，地貌无法保持连续性。对于n≠1的情况，连续性得以保持，并且坡度是可蚀性的函数，这可由该理论预测。处于连续性稳态的地貌可能与地形稳态所预测的有很大不同。对于n
Abstract. The concept of topographic steady state has substantially informed our understanding of the relationships between landscapes, tectonics, climate, and lithology. In topographic steady state, erosion rates are equal everywhere, and steepness adjusts to enable equal erosion rates in rocks of different strengths. This conceptual model makes an implicit assumption of vertical contacts between different rock types. Here we hypothesize that landscapes in layered rocks will be driven toward a state of erosional continuity, where retreat rates on either side of a contact are equal in a direction parallel to the contact rather than in the vertical direction. For vertical contacts, erosional continuity is the same as topographic steady state, whereas for horizontal contacts it is equivalent to equal rates of horizontal retreat on either side of a rock contact. Using analytical solutions and numerical simulations, we show that erosional continuity predicts the form of flux steady-state landscapes that develop in simulations with horizontally layered rocks. For stream power erosion, the nature of continuity steady state depends on the exponent, n, in the erosion model. For n = 1, the landscape cannot maintain continuity. For cases where n ≠ 1, continuity is maintained, and steepness is a function of erodibility that is predicted by the theory. The landscape in continuity steady state can be quite different from that predicted by topographic steady state. For n