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Comparison of methods to estimate sediment flux in ancient sediment routing systems
Earth-Science Reviews ( IF 12.1 ) Pub Date : 2020-08-01 , DOI: 10.1016/j.earscirev.2020.103217
Christopher J. Brewer , Gary J. Hampson , Alexander C. Whittaker , Gareth G. Roberts , Stephen E. Watkins

Abstract The need to predict accurately the volume, timing and location of sediments that are transported from an erosional source region into a basin-depocentre sink is important for many aspects of pure and applied sedimentological research. In this study, the results of three widely used methods to estimate sediment flux in ancient sediment routing systems are compared, using rich input datasets from two systems (Eocene South Pyrenean Foreland Basin, Spain and late-Pleistocene-to-Holocene Gulf of Corinth Rift Basin, Greece) for which mapped, dated sediment volumes provide an independent reference value of sediment accumulation rates. The three methods are: (1) the empirical BQART model, which uses values of drainage basin area, relief, temperature, lithology and water discharge; (2) empirical scaling relationships between characteristic geomorphological parameters of sediment-routing-system segments; and (3) the “fulcrum” model, which uses the palaeohydrological parameters of trunk river channels to estimate downsystem sediment discharge. The BQART model and empirical geomorphological scaling relationships were originally developed using modern sediment routing systems, and have subsequently been applied to ancient systems. In contrast, the “fulcrum” model uses hydrological scaling relationships from modern systems, but was developed principally for application in ancient systems. Our comparative analysis quantifies the sensitivity of the three methods to their input parameters, and identifies the data required to make plausible estimates of sediment flux for ancient sediment routing systems. All three methods can generate estimates of sediment flux that are comparable with each other, and are accurate to at least one order of magnitude relative to independent reference values. The BQART model uses palaeoclimatic and palaeocatchment input data, which are accurate for sub-modern systems but may be highly uncertain in deep-time systems. Corresponding estimates of sediment flux are most sensitive to the accuracy with which the palaeocatchment area is constrained and to palaeoclimatic parameters that reflect temperature and precipitation. The “fulcrum” model uses palaeohydrological input data; its sediment-flux estimates are sensitive to palaeochannel dimensions and, in particular, the duration of bankfull discharge, which is invariably difficult to constrain accurately in deep-time sediment routing systems. This uncertainty can give rise to large potential ranges of sediment-flux estimates. Geomorphological scaling relationships offer comparable, order-of-magnitude accuracy for both sub-modern and deep-time sediment routing systems in which geomorphological segments can be identified, but when used on relatively small sediment routing systems the ranges of sediment volumes deposited can vary greatly, limiting the utility of the technique. We suggest that methods to estimate sediment flux should be chosen for a particular sediment routing system based on the types and uncertainty of available data. Where input parameter values are highly uncertain, such as in deep-time systems, Monte Carlo simulation is an effective tool to calculate probability distributions of estimated sediment flux.

中文翻译:

古代泥沙路径系统中泥沙通量估算方法的比较

摘要 准确预测从侵蚀源区输送到盆地-沉积中心汇的沉积物的体积、时间和位置的需求对于纯粹和应用沉积学研究的许多方面都很重要。在这项研究中,使用来自两个系统(始新世南比利牛斯前陆盆地,西班牙和晚更新世至全新世科林斯裂谷湾)的丰富输入数据集,比较了古代沉积物路径系统中三种广泛使用的估计沉积物通量的方法的结果Basin,Greece),其中测绘的、标注日期的沉积物体积提供了沉积物积累率的独立参考值。这三种方法是:(1)经验BQART模型,它使用流域面积、地势、温度、岩性和排水量的值;(2) 沉积物路径系统段特征地貌参数之间的经验标度关系;(3) “支点”模型,它利用干河道的古水文参数来估计下游系统的泥沙排放。BQART 模型和经验地貌比例关系最初是使用现代沉积物路径系统开发的,随后被应用于古代系统。相比之下,“支点”模型使用来自现代系统的水文比例关系,但主要是为了应用于古代系统而开发的。我们的比较分析量化了三种方法对其输入参数的敏感性,并确定了对古代沉积物路径系统的沉积物通量进行合理估计所需的数据。所有三种方法都可以生成彼此可比较的沉积物通量估计值,并且相对于独立参考值至少精确到一个数量级。BQART 模型使用古气候和古集水区输入数据,这些数据对于亚现代系统是准确的,但在深时系统中可能具有高度不确定性。相应的沉积物通量估计值对古汇水区限制的准确性和反映温度和降水的古气候参数最敏感。“支点”模型使用古水文输入数据;其沉积物通量估计对古河道尺寸很敏感,尤其是对岸边排放的持续时间,这在深时沉积物路径系统中总是难以准确约束。这种不确定性会导致沉积物通量估计的潜在范围很大。地貌比例关系为亚现代和深时沉积物路径系统提供了可比较的数量级精度,其中可以识别地貌段,但当用于相对较小的沉积物路径系统时,沉积物体积的范围可能会有很大差异,限制了该技术的实用性。我们建议,应根据可用数据的类型和不确定性,为特定的沉积物路径系统选择估算沉积物通量的方法。在输入参数值高度不确定的情况下,例如在深时系统中,蒙特卡罗模拟是计算估计沉积物通量概率分布的有效工具。地貌比例关系为亚现代和深时沉积物路径系统提供了可比较的数量级精度,其中可以识别地貌段,但当用于相对较小的沉积物路径系统时,沉积物体积的范围可能会有很大差异,限制了该技术的实用性。我们建议,应根据可用数据的类型和不确定性,为特定的沉积物路径系统选择估算沉积物通量的方法。在输入参数值高度不确定的情况下,例如在深时系统中,蒙特卡罗模拟是计算估计沉积物通量概率分布的有效工具。地貌比例关系为亚现代和深时沉积物路径系统提供了可比较的数量级精度,其中可以识别地貌段,但当用于相对较小的沉积物路径系统时,沉积物体积的范围可能会有很大差异,限制了该技术的实用性。我们建议,应根据可用数据的类型和不确定性,为特定的沉积物路径系统选择估算沉积物通量的方法。在输入参数值高度不确定的情况下,例如在深时系统中,蒙特卡罗模拟是计算估计沉积物通量概率分布的有效工具。可以识别地貌段的亚现代和深时沉积物路径系统的数量级精度,但当用于相对较小的沉积物路径系统时,沉积物体积的范围可能会有很大差异,限制了该系统的效用技术。我们建议,应根据可用数据的类型和不确定性,为特定的沉积物路径系统选择估算沉积物通量的方法。在输入参数值高度不确定的情况下,例如在深时系统中,蒙特卡罗模拟是计算估计沉积物通量概率分布的有效工具。可以识别地貌段的亚现代和深时沉积物路径系统的数量级精度,但是当在相对较小的沉积物路径系统上使用时,沉积的沉积物体积范围可能会有很大差异,限制了该系统的效用。 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?技术。我们建议,应根据可用数据的类型和不确定性,为特定的沉积物路径系统选择估算沉积物通量的方法。在输入参数值高度不确定的情况下,例如在深时系统中,蒙特卡罗模拟是计算估计沉积物通量概率分布的有效工具。我们建议,应根据可用数据的类型和不确定性,为特定的沉积物路径系统选择估算沉积物通量的方法。在输入参数值高度不确定的情况下,例如在深时系统中,蒙特卡罗模拟是计算估计沉积物通量概率分布的有效工具。我们建议,应根据可用数据的类型和不确定性,为特定的沉积物路径系统选择估算沉积物通量的方法。在输入参数值高度不确定的情况下,例如在深时系统中,蒙特卡罗模拟是计算估计沉积物通量概率分布的有效工具。
更新日期:2020-08-01
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