Preservation of meandering river channels in uniformly aggrading channel belts
| Autor: | van de Lageweg, W.I., Schuurman, F., Cohen, K.M., van Dijk, W. M., Shimizu, Y., Kleinhans, M.G., Coastal dynamics, Fluvial systems and Global change, Geomorfologie, Biogeomorphology of Rivers and Estuaries |
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| Rok vydání: | 2015 |
| Předmět: |
Bedform
010504 meteorology & atmospheric sciences preservation Stratigraphy Fluvial bed topography 010502 geochemistry & geophysics 01 natural sciences subaqueous dunes cross-strata Aggradation Taverne point-bar deposits Palaeochannel meandering river Sedimentology Geomorphology Meander scar Earth-Surface Processes 0105 earth and related environmental sciences Geology Point bar numerical simulation morphodynamic modelling Meander |
| Zdroj: | Sedimentology, 63(3), 586. Wiley Online Library |
| ISSN: | 0037-0746 |
| Popis: | 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. © 2015 The Authors. Sedimentology © 2015 International Association of Sedimentologists |
| Databáze: | OpenAIRE |
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