Fluvial floodplains prior to greening of the continents: Stratigraphic record, geodynamic setting, and modern analogues

Ielpi, Alessandro; Fralick, Philip; Ventra, Dario; Ghinassi, Massimiliano; Lebeau, Lorraine E.; Marconato, André; Meek, Robert David; Rainbird, R H

doi:10.1016/j.sedgeo.2018.05.009

Cited by 37 publications

(47 citation statements)

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“…Grain sizes in riverbanks of the Amargosa River, Bonneville Basin, and Toiyabe Basin were qualitatively constrained by Ielpi et al () and Ielpi and Lapôtre (, ) and consist of clay and silt with lenses of very fine to fine sand, similar to Lake Lahontan sediments forming the banks of the Quinn River, NV (Matsubara et al, ). The model correctly predicts that the Quinn River, NV, should be single threaded.…”

Section: Model Resultsmentioning

confidence: 99%

“…Whereas global compilations show that the rise of land plants brought about a sharp increase in mud content within preserved fluvial deposits (McMahon & Davies, ), endorheic basins capable of retaining mud fractions from oceanward transport (e.g., Dott, ) should also have formed before the rise of land plants and provided favorable geodynamic and paleoclimatic settings for the accumulation of mud (Nichols, ). In a compilation of prevegetation fluvial floodplain deposits, Ielpi et al () envisaged a causal link between the rise of supercontinental assemblages, the thorough chemical weathering of large orogenic belts therein, and the deposition of mud‐rich strata in low‐gradient, endorheic‐prone terrestrial basins. Moreover, analyses of fine‐grained Proterozoic sedimentary rocks show that both detrital and pedogenic clays were produced abundantly more than a billion years before the rise of land plants (Tosca et al, ).…”

Section: Discussionmentioning

confidence: 99%

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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: Model Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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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“…As a case in point, Ielpi et al . 's () review of pre‐vegetation floodplains included extensive reference to modern non‐vegetated fluvial systems, with examples drawn both from humid exorheic systems (Icelandic coastal plains) and dryland endorheic systems (Death Valley in California, USA and Salar de Uyuni, Bolivia). Salar de Uyuni is the world's largest salt lake, and is periodically supplied with water and sediment by low‐gradient, ephemeral rivers such as the Río Colorado.…”

Section: Introductionmentioning

confidence: 99%

“…Ielpi et al . 's () review made reference to much of this previous work, highlighting how the Río Colorado provides a modern analogue for pre‐vegetation floodplains that were variably composed of features such as floodbasins, splay complexes, and minor levees. Significantly, however, Ielpi et al .…”

Section: Introductionmentioning

confidence: 99%

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Cascades of sub‐decadal, channel‐floodplain changes in low‐gradient, non‐vegetated reaches near a dryland river terminus: Salar de Uyuni, Bolivia

Tooth

Yao

2018

Earth Surf Processes Landf

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The terminus of the ephemeral Río Colorado is located at the margins of Salar de Uyuni, Bolivia, the world's largest salt lake. The low‐gradient (<0.0006 m m‐1), non‐vegetated reaches approaching the terminus provide an excellent natural laboratory for investigating cascades of channel‐floodplain changes that occur in response to quasi‐regular flows (at least once annually) and fine‐grained sediment supply (dominantly silt and clay). High‐resolution satellite imagery (<0.65 m, various dates from 2004 onwards) and field data reveal widespread, pronounced and rapid morphodynamics on sub‐decadal timescales, including channel erosion and chute cutoff formation, and development of crevasse channels and splays, floodouts (unchannelled surfaces at channel termini), and erosion cells (floodplain scour‐transport‐fill features). In particular, following high annual precipitation (>400 mm) in 2004–2005 and two subsequent high magnitude daily precipitation events (~40 mm), all of which led to widespread flooding, numerous crevasse splays formed between 2004 and 2016, avulsions occurred at nearby floodouts, and erosion cells downstream of the splays and floodouts underwent striking morphological changes. High‐precision GPS data reveal two preferential localities for erosion cell development: partially or fully abandoned channels with crevasse splay remnants, and topographic lows between channels. In this overall low‐gradient setting, comparatively high gradients (up to ~0.0006 m m‐1) at the edge of splay deposits and topography created by crevasses and abandoned channels may initiate knickpoint retreat and thereafter erosion cell development. Abandoned channels with splays tend to give rise to narrow, deep erosion cells, while topographic lows promote relatively shallow, wide erosion cells. In both situations, erosion cells may extend upslope and downslope, and eventually connect to form straight channels. The channel‐floodplain morphodynamics near the Río Colorado terminus extend previous analyses of low‐gradient, dryland river systems, particularly because the lack of vegetation and quasi‐regular floods drive cascades of rapid changes on sub‐decadal timescales. © 2018 John Wiley & Sons, Ltd.

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Channel mobility drives a diverse stratigraphic architecture in the dryland Mojave River (California, USA)

Ielpi

Lapôtre

Finotello

et al. 2020

Earth Surf Processes Landf

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The links between flood frequency and rates of channel migration are poorly defined in the ephemeral rivers typical of arid regions. Exploring these links in desert fluvial landscapes would augment our understanding of watershed biogeochemistry and river morphogenesis on early Earth (i.e. prior to the greening of landmasses). Accordingly, we analyse the Mojave River (California), one of the largest watercourses in the Great Basin of the western United States. We integrate discharge records with channel‐migration rates derived from dynamic time‐warping analysis and chronologically calibrated subsidence rates, thereby constraining the river's formative conditions. Our results reveal a slight downstream decrease in bankfull discharge on the Mojave River, rather than the downstream increase typically exhibited by perennial streams. Yet, the number of days per year during which the channel experiences bankfull or higher stages is roughly maintained along the river's length. Analysis of historical peak flood records suggests that the incidence of channel‐formative events responds to modulation in watershed runoff due to the precipitation in the river's headwaters over decades to centuries. Our integrated analysis finally suggests that, while maintaining hydraulic geometries that are fully comparable with many other rivers worldwide, ephemeral desert rivers akin to the Mojave are capable of generating a surprisingly wide range of depositional geometries in the stratigraphic record. © 2020 John Wiley & Sons, Ltd.

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Fluvial floodplains prior to greening of the continents: Stratigraphic record, geodynamic setting, and modern analogues

Cited by 37 publications

References 233 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

Cascades of sub‐decadal, channel‐floodplain changes in low‐gradient, non‐vegetated reaches near a dryland river terminus: Salar de Uyuni, Bolivia

Channel mobility drives a diverse stratigraphic architecture in the dryland Mojave River (California, USA)

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