Revisiting erosion rate estimates from luminescence profiles in exposed bedrock surfaces using stochastic erosion simulations
Revisiting erosion rate estimates from luminescence profiles in exposed bedrock surfaces using stochastic erosion simulations
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DOI：
10.1016/j.epsl.2019.115842
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发表时间：
2019-12-15
影响因子：
5.3
通讯作者：
Moon, S.
中科院分区：
文献类型：
--
作者：
Brown, N. D.;Moon, S.
裸露的基岩在陆地和行星景观中无处不在，但人们对比仪器记录更长的时间尺度上的粒度级基岩侵蚀速率知之甚少。最近建议，使用漂白深度的发光信号作为衡量基岩侵蚀可能适合这些尺度。然而，这种方法假设随着时间的推移，不断侵蚀，侵蚀事件的随机性可能会违反条件。在这里，我们模拟基岩发光漂白响应幂律分布的去除长度和中断持续时间。我们将模拟结果与先前测量的巨石表面的发光曲线进行比较（Sohbati等人，2018年），以说明不太可能出现长时间的间断，并且典型的侵蚀尺度是亚颗粒的，偶尔会出现毫米级的损失，这与有关基岩剥离的微缺陷的想法一致。对于广泛的侵蚀率，测量集成在许多去除事件，产生合理准确的估计，尽管随机性质的模拟过程。我们假设，大卵石顶部的侵蚀速率大于或等于地面水平的侵蚀速率，表明亚临界开裂可能比风成磨蚀对中国帕米尔高原东部卵石退化的影响更大。(C)2019爱思唯尔B.V.保留所有权利。
Exposed bedrock is ubiquitous on terrestrial and planetary landscapes, yet little is known about the rate of granular-scale bedrock erosion on timescales longer than the instrumental record. As recently suggested, using the bleaching depth of luminescence signals as a measure of bedrock erosion may fit these scales. Yet this approach assumes constant erosion through time, a condition likely violated by the stochastic nature of erosional events. Here we simulate bedrock luminescence bleaching in response to power-law distributions of removal lengths and hiatus durations. We compare simulation results with previously measured luminescence profiles from boulder surfaces (Sohbati et al., 2018) to illustrate that prolonged hiatuses are unlikely and that typical erosion scales are sub-granular with occasional loss at mm scales, consistent with ideas about microflaws governing bedrock detachment. For a wide range of erosion rates, measurements are integrated over many removal events, producing reasonably accurate estimates despite the stochastic nature of the simulated process. We hypothesize that the greater or equal erosion rates atop large boulders compared to rates at ground level suggest that subcritical cracking may be more influential than aeolian abrasion for boulder degradation in the Eastern Pamirs, China. (C) 2019 Elsevier B.V. All rights reserved.