Preservation of meandering river channels in uniformly aggrading channel belts
Preservation of meandering river channels in uniformly aggrading channel belts
复制标题
均匀加积河道带中蜿蜒河道的保护
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
M. Kleinhans
中科院分区：
文献类型：
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作者：
W. Lageweg;F. Schuurman;K. Cohen;W. M. Dijk;Y. Shimizu;M. Kleinhans
蜿蜒河流系统的河道带沉积物通常表现出堆积沉积特征的内部结构，由于河道和河床形态在一定范围内的迁移而导致底部接触冲刷。这些边界表面的识别和正确解释对于古河道尺寸的重建和碳氢化合物勘探的流动建模至关重要。因此，了解形成这些表面并将其转移到河流沉积记录中的一系列过程至关重要。在这里，数值模型“NAYS2D”用于模拟一条高度蜿蜒的蜿蜒河流，其合成地层结构可以直接与沉积记录进行比较。模型结果强调了河道深度和迁移速率的时空变化对于河道和坝沉积物生成的重要性。添加净均匀床加积（由于过量的沉积物输入）可以量化各种沉积条件下曲流形态的保存。作者发现，河道迁移造成的冲刷垂直变化的影响通常比河床加积的影响大几个数量级，这解释了河床加积对保存曲流形态的影响有限。此外，曲流带内地层的横向差异远大于河床加积作用的地层印记。反复产生点坝生长的交替，然后截止，导致河道和冲刷特征堆叠的垂直趋势。重要的是，这种垂直堆积趋势在曲折带内横向不同。在蜿蜒带的中心，高返修强度导致产生许多边界表面和扰动的沉积物。靠近边缘的地方，返工很少，并且保留了有限数量边界表面的厚沉积物。因此，这些边缘地区对于完整的河道沉积物具有最高的保存潜力，因此最适合古河道重建。
Channel belt deposits from meandering river systems commonly display an internal architecture of stacked depositional features with scoured basal contacts due to channel and bedform migration across a range of scales. Recognition and correct interpretation of these bounding surfaces is essential to reconstruction of palaeochannel dimensions and to flow modelling for hydrocarbon exploration. It is therefore crucial to understand the suite of processes that form and transfer these surfaces into the fluvial sedimentary record. Here, the numerical model ‘NAYS2D’ is used to simulate a highly sinuous meandering river with synthetic stratigraphic architectures that can be compared directly to the sedimentary record. Model results highlight the importance of spatial and temporal variations in channel depth and migration rate to the generation of channel and bar deposits. Addition of net uniform bed aggradation (due to excess sediment input) allows quantification of the preservation of meander morphology for a wide range of depositional conditions. The authors find that the effect of vertical variation in scouring due to channel migration is generally orders of magnitude larger than the effect of bed aggradation, which explains the limited impact bed aggradation has on preservation of meander morphology. Moreover, lateral differences in stratigraphy within the meander belt are much larger than the stratigraphic imprint of bed aggradation. Repeatedly produced alternations of point bar growth followed by cut‐off result in a vertical trend in channel and scour feature stacking. Importantly, this vertical stacking trend differs laterally within the meander belt. In the centre of the meander belt, the high reworking intensity results in many bounding surfaces and disturbed deposits. Closer to the margins, reworking is infrequent and thick deposits with a limited number of bounding surfaces are preserved. These marginal areas therefore have the highest preservation potential for complete channel deposits and are thus best suited for palaeochannel reconstruction.
影响因子：
18.3
作者：
Constantine, Jose Antonio;Dunne, Thomas;Lazarus, Eli D.
通讯作者：
Lazarus, Eli D.