Reconstruction of a sandy point‐bar deposit: implications for fluvial facies analysis

Swan, Alistair; Hartley, Adrian J.; Owen, Amanda; Howell, John

doi:10.1002/9781119424437.ch17

Cited by 21 publications

(22 citation statements)

References 52 publications

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“…This idea is consistent with recent observations of a modern point-bar deposit along a highly mobile unvegetated river meander in the Toiyabe Basin, NV (Ielpi & Lapôtre, 2019b), which is dominated by sand-sized materials with little intercalated mud. If found to be representative of other unvegetated meandering streams, the observed stratigraphy in the Toiyabe Basin is inconsistent with heterolithic lateral accretion sets being diagnostic of river meandering (as also suggested by, e.g., Hartley et al, 2018;McMahon & Davies, 2018b;Swan et al, 2018).…”

Section: Journal Of Geophysical Research: Earth Surfacementioning

confidence: 85%

Model for the Formation of Single‐Thread Rivers in Barren Landscapes and Implications for Pre‐Silurian and Martian Fluvial Deposits

et al. 2019

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Flume experiments and field observations show that bank vegetation promotes the formation of narrow and deep single‐thread channels by strengthening riverbanks. Consistent with this idea, the pre‐Silurian fluvial record generally consists of wide monotonous sand bodies often interpreted as deposits of shallow braided rivers, whereas single‐thread rivers with muddy floodplains become more recognizable in Silurian and younger rocks. This shift in the architecture of fluvial deposits has been interpreted as reflecting the rise of single‐thread rivers enabled by plant life. The deposits of some single‐thread rivers, however, have been recognized in pre‐Silurian rocks, and recent field studies have identified meandering rivers in modern unvegetated environments. Furthermore, single‐thread‐river deposits have been identified on Mars, where macroscopic plants most likely never evolved. Here we seek to understand the formation of those rarely recognized and poorly characterized single‐thread rivers in unvegetated landscapes. Specifically, we quantitatively explore the hypothesis that cohesive muddy banks alone may enable the formation of single‐thread rivers in the absence of plants. We combine open‐channel hydraulics and a physics‐based erosion model applicable to a variety of bank sediments to predict the formation of unvegetated single‐thread rivers. Consistent with recent flume experiments and field observations, results indicate that single‐thread rivers may form readily within muddy banks. Our model has direct implications for the quantification of riverbank strengthening by vegetation, understanding the hydraulic geometry of modern and ancient unvegetated rivers, interpreting pre‐Silurian fluvial deposits, and unraveling the hydrologic and climate history of Mars.

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Section: Journal Of Geophysical Research: Earth Surfacementioning

confidence: 85%

Model for the Formation of Single‐Thread Rivers in Barren Landscapes and Implications for Pre‐Silurian and Martian Fluvial Deposits

et al. 2019

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“…Such an observation suggests that many sandy meander-belt deposits may not have been identified correctly in the fluvial rock record (e.g. Swan et al, 2019) and may also imply that amalgamated meandering sandy fluvial systems could be under-represented in pre-Devonian fluvial deposits. Our observations suggest that prevegetation meandering rivers may have been more common than previously envisaged, and the examples described here are potential analogues for prevegetation fluvial deposits (Santos and Owen, 2016).…”

Section: Implications For Rivers Developed Before Land Plant Evolutionmentioning

confidence: 99%

Meandering rivers in modern desert basins: Implications for channel planform controls and prevegetation rivers

Santos

Hartley

Mountney

et al. 2019

Sedimentary Geology

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“…Generally, floodplain deposits are fine grained, composed of horizontally bedded (or laminated) and/or massive fine sand, silt, and clay. Root traces and desiccation cracks are ubiquitous in floodplain deposits (e.g., Swan et al, 2018). Nanson and Croke (1992) and Miall (2014) suggested classifying floodplain facies into three broad classes: high-energy non-cohesive floodplain, medium-energy non-cohesive floodplain and low-energy cohesive floodplain.…”

Section: Introductionmentioning

confidence: 99%

“…Nanson and Croke (1992) and Miall (2014) suggested classifying floodplain facies into three broad classes: high-energy non-cohesive floodplain, medium-energy non-cohesive floodplain and low-energy cohesive floodplain. The reality is much more complex, however, because in some cases, floodplain deposits may be truncated by laterally migrating channel bars, resulting in stacked bar deposits and bedload sheets defined as multistory (Alexander, 1992;Gibling, 2006;Miall, 2014) or stacked deposits (Swan et al, 2018). In the East Asian monsoon area, the seasonal climate variation (warm and wet in summer, cold and dry in winter with aeolian activity) may result in specific changes in discharge and sediment and thus related fluvial process and sedimentary facies.…”

Section: Introductionmentioning

confidence: 99%

Diverse floodplain deposits of reworked loess in a monsoon climate (Hanzhong Basin, central China)

et al. 2021

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This paper describes an assemblage of diverse floodplain facies of reworked loess (facies b, c) in a Middle Pleistocene monsoonal setting of the Hanzhong Basin, central China. The vertical and lateral sedimentary sequences show changing energy conditions. Apart from the highest energy in the channel facies (facies a), a relatively high energy floodplain environment (facies b) prevailed in waterlogged conditions, with small, laterally migrating (sub)channels. Facies b generally interfingers with aggrading horizontal sheets of overbank deposits in alluvial pools and swamps in a floodplain with much lower energy (facies c), in which phases of stability (soil formation) occasionally interrupted overbank deposition. Reworked loess forms the main part of the floodplain deposits. The paleosols are considered to have been formed under low hydrodynamic conditions in an interglacial environment. These interglacial conditions follow the commonly assumed glacial conditions of channel facies a. The sedimentary successions in the floodplain show a recurrent composition and cyclicity between wet and dry floodplain sedimentation terminated by stability with soil formation. The cyclic rhythm of stacked high- and low-energy floodplain sediments is attributed to varied intensity of different hydrodynamic flooding events that may have been due to changing monsoonal rainfall or simple intrinsic fluvial behavior.

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Reconstruction of a sandy point‐bar deposit: implications for fluvial facies analysis

Cited by 21 publications

References 52 publications

Model for the Formation of Single‐Thread Rivers in Barren Landscapes and Implications for Pre‐Silurian and Martian Fluvial Deposits

Model for the Formation of Single‐Thread Rivers in Barren Landscapes and Implications for Pre‐Silurian and Martian Fluvial Deposits

Meandering rivers in modern desert basins: Implications for channel planform controls and prevegetation rivers

Diverse floodplain deposits of reworked loess in a monsoon climate (Hanzhong Basin, central China)

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