The role of discharge variability in determining alluvial stratigraphy
The role of discharge variability in determining alluvial stratigraphy
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DOI：
10.1130/g37215.1
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发表时间：
2016
期刊：
影响因子：
5.8
通讯作者：
A. Nicholas;Greg . Smith;M. Amsler;P. Ashworth;J. Best;R. Hardy;S. Lane;O. Orfeo;D. Parsons;A. Reesink;S. Sandbach;C. Simpson;R. Szupiany
中科院分区：
文献类型：
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作者：
A. Nicholas;Greg . Smith;M. Amsler;P. Ashworth;J. Best;R. Hardy;S. Lane;O. Orfeo;D. Parsons;A. Reesink;S. Sandbach;C. Simpson;R. Szupiany
我们说明了潜在的使用基于物理学的建模链接冲积层的大河形态和动力学。模型模拟，验证从里约巴拉那州，阿根廷，使用探地雷达数据，显示了强大的酒吧规模集厚度和通道深度之间的关系，适用于广泛的河流模式和酒吧类型。我们发现，水文制度，指标流量变化和洪水持续时间，施加一阶的影响，形态动力学，因此酒吧设置厚度，平面形态本身可能是一个误导性的变量解释存款。事实上，我们的研究结果表明，河流在对比水文制度的演变可能有非常相似的形态，但其特点是在地层的显着差异。这一认识代表了一个重要的限制，建立理论的应用，连接河流地形冲积矿床，并强调需要获得现场证据的流量变化时，开发古环境重建。模型模拟表明，潜在的古水流方差的指标，得出这样的证据。
We illustrate the potential for using physics-based modeling to link alluvial stratigraphy to large river morphology and dynamics. Model simulations, validated using ground penetrating radar data from the Rio Parana, Argentina, demonstrate a strong relationship between bar-scale set thickness and channel depth, which applies across a wide range of river patterns and bar types. We show that hydrologic regime, indexed by discharge variability and flood duration, exerts a first-order influence on morphodynamics and hence bar set thickness, and that planform morphology alone may be a misleading variable for interpreting deposits. Indeed, our results illustrate that rivers evolving under contrasting hydrologic regimes may have very similar morphology, yet be characterized by marked differences in stratigraphy. This realization represents an important limitation on the application of established theory that links river topography to alluvial deposits, and highlights the need to obtain field evidence of discharge variability when developing paleoenvironmental reconstructions. Model simulations demonstrate the potential for deriving such evidence using metrics of paleocurrent variance.