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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Desert pavement dynamics: numerical modeling and field-based calibration
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Desert pavement dynamics: numerical modeling and field-based calibration

机译：沙漠路面动力学：数值模拟和基于现场的标定

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Desert pavements are widely used as a relative surface-dating tool because they are progressively better developed on surfaces ranging from thousands to hundreds of thousands of years in age. Recent work, however, has highlighted the dynamic nature of pavements and undermined their use as surface-age indicators. Quade (2001) proposed that latest Pleistocene vegetation advances destroyed all Mojave Desert pavements above 400 m elevation, making ail such pavements Holocene in age. In an effort to reconcile young-pavement evidence with their widespread use as Pleistocene surface-age indicators, we developed a numerical model based on the classic conceptual model in which pavements co-evolve with their underlying eolian epipedons over millennial timescales. In this co-evolutionary process, fine-grained eolian deposition and A(v)-horizon development within the eolian epipedon promotes surface clast motion and pavement development, enhancing the eolian-sediment-trapping ability of the pavement in a positive feedback. Model results illustrate the multi-scale nature of pavement dynamics: pavements may require tens of thousands of years to fully develop from a newly abandoned alluvial surface, but may heal over timescales of decades to centuries if a mature eolian epipedon is present. As such, there is no inconsistency between rapid pavement healing and a Pleistocene age for the underlying alluvial surface. To calibrate the model, we conducted surficial geologic mapping and pavement-sedimentological analysis on two desert piedmonts. Our study areas include both proximal and distal fan environments, illustrating the role of parent-material texture in controlling the mode of pavement formation. Using available geochronology, our work provides a rigorous calibration of pavement formation rates in our study areas and provides evidence supporting the use of pavements as local relative surface-age indicators over Holocene to late Pleistocene timescales. Copyright (c) 2007 John Wiley & Sons, Ltd.
机译：沙漠路面被广泛用作一种相对的表面约会工具，因为它们在几千年至数十万年的历史上逐渐发展得越来越好。但是，最近的工作强调了人行道的动态特性，并破坏了它们作为表面年龄指标的用途。 Quade（2001）提出，最新的更新世植被进展破坏了海拔400 m以上的所有莫哈韦沙漠路面，并使所有此类路面变老。为了调和年轻路面证据作为更新世表面年龄指标的广泛应用，我们在经典概念模型的基础上开发了一个数值模型，其中，路面与它们潜在的风成岩表层在千禧年尺度上共同演化。在这种共同进化过程中，风成岩表层内细粒的风成岩沉积和水平（A）-水平发育促进了地表运动和路面的发展，增强了路面的风积物捕获能力。模型结果说明了路面动力学的多尺度性质：路面可能需要数万年的时间才能从新近废弃的冲积表面完全发育，但如果存在成熟的风积石表皮，则可能会在数十年至数百年的时间内愈合。这样，在快速的路面愈合与底层冲积层的更新世年龄之间没有矛盾。为了校准模型，我们在两个沙漠山前进行了表面地质制图和路面沉积分析。我们的研究领域包括近端风扇环境和远端风扇环境，说明了母材纹理在控制路面形成方式中的作用。利用现有的年代学，我们的工作对研究区的人行道形成速率进行了严格的校准，并提供了证据支持将人行道用作全新世至晚更新世时标的局部相对地面年龄指标。版权所有（c）2007 John Wiley＆Sons，Ltd.

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