The Hydraulic Autogenesis of Distinct Cyclicity In Delta Foreset Bedding: Flume Experiments

Muto, Tetsuji; Yamagishi, Chizuru; Sekiguchi, Takuya; Yokokawa, Miwa; Parker, Gary

doi:10.2110/jsr.2012.49

Cited by 29 publications

(49 citation statements)

References 41 publications

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“…These knickpoints take the form of cyclic steps, that is, trains of upstream-migrating bedforms, each bounded by hydraulic jumps and can form under conditions of constant stationary base level, with new steps forming at the downstream end of the reach as previously formed steps migrate out of the reach. Muto et al (2012) have observed similar quasi-equilibrium trains of cyclic steps on the alluvial top set of prograding deltas.…”

Section: Introductionmentioning

confidence: 65%

“…Froude-supercritical flow can generate a variety of bed states in alluvium, including plane beds, upstream-or downstreammigrating antidunes and cyclic steps. For a phase diagram of these bedforms see Muto et al (2012). Under the right conditions, upstream-migrating cyclic steps of permanent (rather than transient) form can manifest themselves in terms of trains of sharp knickpoints (Taki and Parker, 2005;Yokokawa et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

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Multiple knickpoints in an alluvial river generated by a single instantaneous drop in base level: experimental investigation

Cantelli

Muto

2014

Earth Surf. Dynam.

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Abstract. Knickpoints often form in bedrock rivers in response to base-level lowering. These knickpoints can migrate upstream without dissipating. In the case of alluvial rivers, an impulsive lowering of base level due to, for example, a fault associated with an earthquake or dam removal commonly produces smooth, upstreamprogressing degradation; the knickpoint associated with suddenly lowered base level quickly dissipates. Here, however, we use experiments to demonstrate that under conditions of Froude-supercritical flow over an alluvial bed, an instantaneous drop in base level can lead to the formation of upstream-migrating knickpoints that do not dissipate. The base-level fall can generate a single knickpoint, or multiple knickpoints. Multiple knickpoints take the form of cyclic steps, that is, trains of upstream-migrating bedforms, each bounded by a hydraulic jump upstream and downstream. In our experiments, trains of knickpoints were transient, eventually migrating out of the alluvial reach as the bed evolved to a new equilibrium state regulated with lowered base level. Thus the allogenic perturbation of base-level fall can trigger the autogenic generation of multiple knickpoints which are sustained until the alluvial reach recovers a graded state.

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Section: Introductionmentioning

confidence: 65%

Section: Discussionmentioning

confidence: 99%

Multiple knickpoints in an alluvial river generated by a single instantaneous drop in base level: experimental investigation

Cantelli

Muto

2014

Earth Surf. Dynam.

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“…However, the interpretation of gravity-flow deposits has considerably changed during recent years and recently the deposition by supercritical density flows has become a major focus of research, changing previous views (Postma et al 2009;. Fielding 2006;Muto et al 2012;Lang & Winsemann 2013;Cartigny et al 2014;Dietrich et al 2016;Massari 2017;Lang et al 2017a, b). Fielding 2006;Muto et al 2012;Lang & Winsemann 2013;Cartigny et al 2014;Dietrich et al 2016;Massari 2017;Lang et al 2017a, b).…”

Section: Delta Styles and Depositional Processesmentioning

confidence: 99%

“…Based on their wavelengths and asymmetry these deposits may represent either large antidunes or net-depositional cyclic steps (Kostic 2011;Winsemann et al 2011;Muto et al 2012;Cartigny et al 2014). Isolated scour fills with backsets are interpreted as the preserved hydraulic jump zone of cyclic steps (Muto et al 2012;Cartigny et al 2014) that probably formed on the delta plain during major meltwater discharges. 5B) indicates cyclic steps or chutes-and-pools with superimposed antidunes Zhong et al 2015;Lang et al 2017a).…”

Section: Gilbert-type Deltas (Fa1)mentioning

confidence: 99%

“…Initial mouthbars formed close to the channel axis, leading to flow splitting and the formation of new terminal distributary channels at different scales. The formation of V-shaped scours and intraclasts may be related to the formation of cyclic steps during supercritical flow conditions (Strong & Paola 2008;Muto et al 2012;. 10D, E) are interpreted as bases of distributary channels (Olariu & Bhattacharya 2006;Lee et al 2007).…”

Section: Shoal-water Deltas (Fa2)mentioning

confidence: 99%

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Ice‐marginal forced regressive deltas in glacial lake basins: geomorphology, facies variability and large‐scale depositional architecture

Winsemann

Lang

Polom

et al. 2018

Boreas

130

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Brandes, C. 2018 (October): Ice-marginal forced regressive deltas in glacial lake basins: geomorphology, facies variability and large-scale depositional architecture.This study presents a synthesis of the geomorphology, facies variability and depositional architecture of ice-marginal deltas affected by rapid lake-level change. The integration of digital elevation models, outcrop, borehole, groundpenetrating radar and high-resolution shear-wave seismic data allows for a comprehensive analysis of these delta systems and provides information about the distinct types of deltaic facies and geometries generated under different lake-level trends. The exposed delta sediments record mainly the phase of maximum lake level and subsequent lake drainage. The stair-stepped profiles of the delta systems reflect the progressive basinward lobe deposition during forced regression when the lakes successively drained. Depending on the rate and magnitude of lake-level fall, fanshaped, lobate or more digitate tongue-like delta morphologies developed. Deposits of the stair-stepped transgressive delta bodies are buried, downlapped and onlapped by the younger forced regressive deposits. The delta styles comprise both Gilbert-type deltas and shoal-water deltas. The sedimentary facies of the steep Gilberttype delta foresets include a wide range of gravity-flow deposits. Delta deposits of the forced-regressive phase are commonly dominated by coarse-grained debrisflow deposits, indicating strong upslope erosion and cannibalization of older delta deposits. Deposits of supercritical turbidity currents are particularly common in sand-rich Gilbert-type deltas that formed during slow rises in lake level and during highstands. Foreset beds consist typically of laterally and vertically stacked deposits of antidunes and cyclic steps. The trigger mechanisms for these supercritical turbidity currents were both hyperpycnal meltwater flows and slope-failure events. Shoal-water deltas formed at low water depths during both low rates of lake-level rise and forced regression. Deposition occurred from tractional flows. Transgressive mouthbars form laterally extensive sand-rich delta bodies with a digitate, multi-tongue morphology. In contrast, forced regressive gravelly shoal-water deltas show a high dispersion of flow directions and form laterally overlapping delta lobes. Deformation structures in the forced-regressive ice-marginal deltas are mainly extensional features, including normal faults, small graben or half-graben structures and shear-deformation bands, which are related to gravitational delta tectonics, postglacial faulting during glacial-isostatic adjustment, and crestal collapse above salt domes. A neotectonic component cannot be ruled out in some cases. facies and the larger-scale depositional architecture. The results are compared with other marine and lacustrine delta examples from the literature, and provide information about the distinct types

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2020

Rivers in the Landscape

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The Hydraulic Autogenesis of Distinct Cyclicity In Delta Foreset Bedding: Flume Experiments

Cited by 29 publications

References 41 publications

Multiple knickpoints in an alluvial river generated by a single instantaneous drop in base level: experimental investigation

Multiple knickpoints in an alluvial river generated by a single instantaneous drop in base level: experimental investigation

Ice‐marginal forced regressive deltas in glacial lake basins: geomorphology, facies variability and large‐scale depositional architecture

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