Sticky stuff: Redefining bedform prediction in modern and ancient environments
Sticky stuff: Redefining bedform prediction in modern and ancient environments
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DOI：
10.1130/g36262.1
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发表时间：
2015-05
期刊：
影响因子：
5.8
通讯作者：
R. Schindler;D. Parsons;L. Ye;J. Hope;J. Baas;J. Peakall;A. Manning;Rebecca J. Aspden;J. Malarkey;S. Simmons;D. Paterson;I. D. Lichtman;A. Davies;P. Thorne;S. Bass
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文献类型：
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作者：
R. Schindler;D. Parsons;L. Ye;J. Hope;J. Baas;J. Peakall;A. Manning;Rebecca J. Aspden;J. Malarkey;S. Simmons;D. Paterson;I. D. Lichtman;A. Davies;P. Thorne;S. Bass
对于无粘性沉积物，水下底形的尺寸和动力学是众所周知的。然而，物理凝聚力的影响，赋予粘性粘土在混合砂泥基质尚未检查，尽管其公认的影响，沉积物的稳定性。在这里，我们提出了一系列的控制实验室实验，以建立底质粘土含量对水下底形动力学的影响内的砂和粘土的混合物暴露于单向流。结果表明，床形尺寸和陡度线性下降的粘土含量，并与现有的床形尺寸的预测，建立在无粘性沉积物的比较，揭示了显着的过度预测床形尺寸的所有，但最低的粘土含量检查。基底粘土含量对底形尺寸的深刻影响对现代和古代环境中的解释有许多重要的影响，包括河口系统的粗糙度和底形高度降低，以及经常引用的浊积岩中缺乏大沙丘交叉集。因此，这些结果提供了一个步骤的变化，我们的理解在这些，和许多其他的沉积环境中的底形形成和动力学。
The dimensions and dynamics of subaqueous bedforms are well known for cohesionless sediments. However, the effect of physical cohesion imparted by cohesive clay within mixed sand-mud substrates has not been examined, despite its recognized influence on sediment stability. Here we present a series of controlled laboratory experiments to establish the influence of substrate clay content on subaqueous bedform dynamics within mixtures of sand and clay exposed to unidirectional flow. The results show that bedform dimensions and steepness decrease linearly with clay content, and comparison with existing predictors of bedform dimensions, established within cohesionless sediments, reveals significant over-prediction of bedform size for all but the lowermost clay contents examined. The profound effect substrate clay content has on bedform dimensions has a number of important implications for interpretation in a range of modern and ancient environments, including reduced roughness and bedform heights in estuarine systems and the often cited lack of large dune cross-sets in turbidites. The results therefore offer a step change in our understanding of bedform formation and dynamics in these, and many other, sedimentary environments.