Variations in natural levee morphology in anastomosed channel flood plain complexes

Adams, P. N.; Slingerland, Rudy; Smith, Norman D.

doi:10.1016/j.geomorph.2003.10.005

Cited by 106 publications

(129 citation statements)

References 34 publications

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Section: The Channel Fill and Sheet Splay Depositsmentioning

confidence: 99%

“…The lateral stability of these channels (absence of point bar accretion and limited cross-bedding and lenticular shape) in the Iharkút open-pit shows the typical characteristics of an anastomosing system (e.g. Smith, 1976;Smith and Smith, 1980;Gibling and Rust, 1990;Eberth and Miall, 1991;Kirschbaum and McCabe, 1992;Makaske, 2001;Gradźinski et al, 2003;Adams et al, 2004;Horiuchi et al, 2012). Such fluvial systems are generally characterised by lateral stability of the channels, which is due to the very low channel gradients (e.g.…”

Section: The Channel Fill and Sheet Splay Depositsmentioning

confidence: 99%

“…Makaske, 2001), the cohesive bank sediments (e.g. Nadon, 1994;Adams et al, 2004) and/or the vegetation controls (e.g. Smith, 1976;Smith and Smith, 1980;Gradźinski et al, 2003).…”

Section: The Channel Fill and Sheet Splay Depositsmentioning

confidence: 99%

“…Such fluvial systems are generally characterised by lateral stability of the channels, which is due to the very low Smith, 1976; Gradźinski et al, 2003). On the other hand, the resistant levee deposits also had important role in the lateral stability of the channel, because the levees aggrade faster than any other part of the anastomosed system due to their rapid depositional rates and coarser material (Nadon, 1994;Adams et al, 2004).However, the levee deposits (yellowish red, coarser particle sized paleosols with tiny irregular root traces) are subordinate in the Iharkút open-pit, which emphasizes the role of the vegetation in the lateral stability of the channels.The other frequent sandstone bodies are splay sandstones interpreted as crevasse splay deposits having typically flat, non-erosional base ( Fig 4F) and a width/ thickness ratio of >15.The grain size is usually medium to fine sandstone, coarser sediments are completely absent near the erosional surface. These channels and sheet splays had a significant role in the transportation of sediments and bones from the background area and they pumped finer axes oriented sub-vertically, the bone material was not sorted by shape (Botfalvai et al, 2015), and the channel-fill comprises several stacked deposits.…”

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confidence: 99%

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Facies architecture and palaeoenvironmental implications of the upper Cretaceous (Santonian) Csehbánya formation at the Iharkút vertebrate locality (Bakony Mountains, Northwestern Hungary)

Botfalvai

Haas

Bodor

et al. 2016

Palaeogeography, Palaeoclimatology, Palaeoecology

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The Csehbánya Formation (Santonian), exposed in the Iharkút open-pit, BakonyMountains, Hungary, is made up of a cyclic alternation of conglomerate, sandstone, and variegated siltstone and clay deposited in a fluviolacustrine environment. As a result of continuous excavation since 2002 it has yielded rich and diverse continental vertebrate and plant assemblages. A facies and architectural analysis of the Csehbánya Formation at this location identified four main lithofacies associations with eight subtypes consisting of (1) lenticular sandstones representing river channels, (2) conglomerates with sandstone (coarse grained likewise representing channel deposits), (3) heterolithic-channel fill (high density flash flow deposits) (4) splay sandstones produced by crevasse splays, (5) dark sandy siltstone (small-scale stagnant pool deposits with high organic content), (6) greenish-grey claystone (deposits of shallow lakes and ponds), (7) reddish (moderately drained) paleosols, (7) yellowish, mottled (hydromorphic) paleosols.The sedimentological investigations revealed that the terrestrial deposits exposed by the Iharkút open-pit were formed in an anastomosing fluvial system because: (i) the alluvial architecture is characterized by large proportion of overbank deposits encasing the channel sandstone bodies, (ii) the ribbon shaped sandstone bodies are dominant, (iii) cross-bedding and lateral accretion are almost completely absent in the channel fill deposits and (iv) the sandstone bodies are clearly isolated from each other, embedded in floodplain sediments, suggesting multiple co-existing channels.The most important vertebrate fossil site (SZ-6) was examined in special detail because it shows peculiar lithological features. The layers richest in fossils (Unit 1) of site is interpreted as a lag deposit formed during an episodic high density flash flood event representing a relatively short time interval, i.e., probably within a single rainy season. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 1 1. INTRODUCTIONA significant part of continental vertebrate fossils is found in alluvial deposits thus the reconstruction of the depositional history of alluvial sequences is the main goal of any sedimentological, paleontological and taphonomical examination of vertebrate sites (Behrensmeyer, 1982(Behrensmeyer, , 1988Retallack, 1984; Badgley, 1986a,b;Eberth and Miall, 1991;Nadon, 1993;Therrien, 2005;Roberts, 2007). One of the reasons for the accumulation of rich vertebrate fossil-bearing strata is that a relatively high number of animals are attracted to the floodplain due to abundant water and food supply (different plants or prey), which can result in a rich accumulation of bones (Behrensmeyer, 1988;Nadon, 1993;Andersson and Kaakinen, 2004). Furthermore, certain floodplain environments are favourable for bone preservation because of the relatively high depositional rate, post-mortem transportation, and reworking of animal remains by various fluvial processes (Behrensmeyer, 1988;Aslan and Behrensmeyer, 1996)....

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Section: The Channel Fill and Sheet Splay Depositsmentioning

confidence: 99%

Section: The Channel Fill and Sheet Splay Depositsmentioning

confidence: 99%

“…Makaske, 2001), the cohesive bank sediments (e.g. Nadon, 1994;Adams et al, 2004) and/or the vegetation controls (e.g. Smith, 1976;Smith and Smith, 1980;Gradźinski et al, 2003).…”

Section: The Channel Fill and Sheet Splay Depositsmentioning

confidence: 99%

mentioning

confidence: 99%

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Facies architecture and palaeoenvironmental implications of the upper Cretaceous (Santonian) Csehbánya formation at the Iharkút vertebrate locality (Bakony Mountains, Northwestern Hungary)

Botfalvai

Haas

Bodor

et al. 2016

Palaeogeography, Palaeoclimatology, Palaeoecology

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“…Levees Smith, 1986;Cazanacli and Smith, 1998;Brierley et al, 1997;Ferguson and Brierley, 1999;Saucier, 1994;Adams et al, 2004;Klasz et al, 2014;Aalto et al, 2008;Park andLatrubesse, 2015 b. Bank-top splays Coleman, 1969;Alexander et al, 1999;Van de Lagerweg et al, 2013;Shen et al, 2015 c. Channel bars and islands Bristow, 1987;Gurnell et al, 2001;Mardhiah et al 2015;Rozo et al, 2014;Wintenberger et al, 2015 SL Secondary linear systems d. Accessory channels Dunne et al, 1998;Lewin and Ashworth, 2014a;Lewin and Ashworth, 2014b;Latrubesse, 2015 e. Crevasse splays O'Brien andWells, 1986;Smith et al, 1989;Smith and Pérez-Arlucea, 1994;Bristow et al, 1999;Farrell, 2001;Toonen et al, 2016 f. Crevasses with deltas Bogen, 1982;Tye and Coleman, 1989;Latrubesse and Franzinelli, 2002;Rowland et al, 2010;Olariu et al, 2012g.…”

Section: Spillagesmentioning

confidence: 99%

Spillage sedimentation on large river floodplains

Lewin

Ashworth

Strick

2016

Earth Surf Processes Landf

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Active deposition across the floodplains of large rivers arises through a variety of processes; collectively these are here termed 'spillage sedimentation'. Three groups of 11 spillage sedimentation styles are identified and their formative processes described. Form presences on large river floodplains show different combinations of active spillage styles. Only some large floodplains have prominent levees; some have coarse splays; many have accessory channel dispersion and reworking, while still-water sedimentation in lacustrine environments dominates some lower reaches. Infills are also commonly funnelled into prior, and often linear, negative relief forms relating to former migration within the mainstream channel belt.Shuttle Radar Topography Mission (SRTM) and Landsat 8 data are used to map spillage form types and coverage along a 1700 km reach of the Amazon that has an active floodplain width of up to 110 km with a systematic character transformation down-valley. Spillage forms associated directly with mainstream processes rarely account for more than 5% of the floodplain deposits. There is a marked decrease in floodplain point bar complexes (PBC) over 1700 km downstream (from 34% to 5%), and an increase in the prevalence of large water bodies (2% to 37%) and accompanying internal crevasses and deltas (0% to 5%). Spillage sedimentation is likely within the negative relief associated with these forms, depending on mainstream sediment-laden floodwater inputs.Spillage style dominance depends on the balance between sediment loadings, hydrological sequencing, and morphological opportunity. Down-river form sequences are likely to follow gradient change, prior up-river sediment sequestration and the altered nature of spilled loads, but also crucially, local floodplain relief and incident water levels and velocities at spillage times. Considering style distribution quantitatively, as a spatially distributed set of identifiable forms, emphasizes the global variety to spillage phenomena along and between large rivers.

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Processes governing decadal-scale depositional narrowing of the major tidal channel in San Pablo Bay, California, USA

Wegen

Jaffe

2014

J. Geophys. Res. Earth Surf.

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Bathymetric measurements show that a deep, subtidal channel in San Pablo Bay, California, has consistently narrowed during the past 150 years. This raises general questions on the seasonal and intertidal morphodynamic processes acting at the subtidal channel-shoal interface. The current work addresses these questions using a process-based morphodynamic model (Delft3D). Model results reveal considerable morphodynamic activity during a tidal cycle. Deposition on the channel margin is largest during flooding of the shoals. Erosion rates (mainly occuring during ebb) remain relatively small, so that net accretion occurs on much of the channel margin. A remarkable finding is that locally generated wind waves are responsible for shoal extension and depositional channel narrowing. High suspended sediment concentration (SSC) in the channel is a critical factor. Apart from sediment supply during high river flow, wind waves suspending sediment on the shoals cause high SSC levels in the channel at ebb. Sensitivity analysis shows that wind direction even determines the location of channel margin accretion. Fluvial sediment supply is another cause of high SSC in the channel. Density currents, 3-D circulation flows, sea level rise, or varied sediment characteristics only have a limited effect on the erosion and sedimentation patterns. A 30 year forecast shows that deeper shoals and decreasing fluvial sediment supply lower SSC levels in the channel, limit channel margin accretion, and even lead to net channel margin erosion in some areas. Channel shape thus remains subject to dynamic processes related to local variations in sediment supply, albeit to a more limited extent than in earlier decades.

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Variations in natural levee morphology in anastomosed channel flood plain complexes

Cited by 106 publications

References 34 publications

Facies architecture and palaeoenvironmental implications of the upper Cretaceous (Santonian) Csehbánya formation at the Iharkút vertebrate locality (Bakony Mountains, Northwestern Hungary)

Facies architecture and palaeoenvironmental implications of the upper Cretaceous (Santonian) Csehbánya formation at the Iharkút vertebrate locality (Bakony Mountains, Northwestern Hungary)

Spillage sedimentation on large river floodplains

Processes governing decadal-scale depositional narrowing of the major tidal channel in San Pablo Bay, California, USA

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