An exhumed fine‐grained meandering channel in the lower Permian Clear Fork Formation, north‐central Texas

Simon, Sharane S.T.; Gibling, Martin R.; DiMichele, William A.; Chaney, Dan S.; Koll, Rebecca A.

doi:10.1002/9781119424437.ch6

Cited by 3 publications

(3 citation statements)

References 61 publications

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“…This element is interpreted as channel abandonment or channel thalweg fill based on the geometry, sedimentary facies assemblage and palaeocurrent data (cf. Durkin et al ., 2015; Simon et al ., 2018). The trough and planar cross‐stratified sandstone with convex‐up geometry reflects the deposition from bedload by migration of medium to small‐scale sinuous dunes at the channel floor.…”

Section: Resultsmentioning

confidence: 99%

Evolution of a gradually abandoned Oligocene fluvial palaeovalley fill: Abu‐Roash area, north Western Desert, Egypt

Selim

2021

Sedimentology

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Little is known about the evolution and gradual abandonment of the fluvial channel and associated sedimentary architecture preserved in the ancient sedimentary rock record. This research aims to analyze the changes and evolution of a gradually abandoned fluvial valley and associated within-channel deposits and architecture from the rock record. This is achieved through detailed photogrammetry, outcrop sedimentology and quantification of palaeochannel parameters for the Oligocene palaeovalley fill of the north Western Desert basin of Egypt. The three-dimensional vertical Oligocene outcrops and trenches of the study area provide the opportunity to analyze sedimentary facies, ichnology, architectural elements and evolution of the gradually abandoned fluvial channel belt. This paper presents a detailed model for the gradual abandonment and evolution of the fluvial palaeovalley through the stepwise transition from braided to meandering channel systems. This includes the transition from a bedload-dominated, low sinuosity, braided channel that prominently features downstream-accreted, mid-channel and compound bars, to a small, mixed and suspended load-dominated intermediate sinuosity (underfit) channel that is characterized by heterolithicdominated point bars, floodplain and mud-plugs via a large, sand-dominated, intermediate sinuosity channel with laterally accreted bars of transitional stage. The gradual abandonment of the fluvial palaeovalley is also associated with a successive decrease of the channel width and depth from >800 to 166 m and from 12 to 5 m, respectively. The successive abandonment is also associated with a gradual increase in the diversity and abundance of Scoyenia-Termitichnus ichnofacies groups, and vice versa in the Skolithos ichnofacies group. The successive decrease in channel width with gradual abandonment of the Oligocene palaeovalley is probably attributed to autogenic gradual avulsion, rather than allogenic. Comparison between the Oligocene palaeovalley fill and the modern analogues indicate the similarities in channel pattern changes and channel dimension through filling stages and differ from most modern counterparts because it is aggradational. This research enhances the understanding of the sedimentological characteristics and stratigraphic architecture of the gradually abandoned fluvial channels in the rock record and introduces insights for prediction of within-channel facies and architectural heterogeneities of the fluvial channel reservoirs.

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Section: Resultsmentioning

confidence: 99%

Evolution of a gradually abandoned Oligocene fluvial palaeovalley fill: Abu‐Roash area, north Western Desert, Egypt

Selim

2021

Sedimentology

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“…The collection of Δf values from the intermediate depth zones of bars (Fig. 2A) carries a representative signature of the main channel flow, since other effects are minimized at this depth, for example: (i) flow distortion induced by the interaction with bar-top topography (for example, scroll bars; Ielpi & Ghinassi, 2014); (ii) floodwater reentering the main channel in the recessive stages of exceptional discharge events (Loveless et al, 2000;Ghinassi et al, 2013;Simon et al, 2018); or (iii) by interactions with the channelbottom boundary layer. The high density of Δf values within the range of 90 to 120°in mid-channel and bank-attached bars demonstrates that dune migration transverse to the dip azimuth of bar-slope surfaces is a fundamental process of accretion for both types of bars.…”

Section: Significance Of Flow Variance In Riversmentioning

confidence: 99%

Distinguishing mid‐channel and bank‐attached fluvial bars by flow divergence: Implications for the interpretation of stratigraphic records

et al. 2021

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The characterization of ancient fluvial-channel bars informs predictions of sedimentary facies distribution, and hence they are critical for interpreting river morphodynamics through time. Within active fluvial channels, sediment storage occurs along the banks or along their axial portion, generating bank-attached or mid-channel bars, respectively. This study introduces the angle of flow divergence (Δf), measured as the angle between the azimuths of bar accretionary slopes and local dune migration, and quantitatively explores its distribution in 103 channel reaches that have a sandy bed load and clear water. This dataset includes both mid-channel and bank-attached bars from low-variable peak discharge rivers of Russia and Brazil. Remotely sensed evidence shows that dune migration transverse to the dip azimuth of bar slopes (Δf ≅ 90-110°) occurs both in mid-channel and bank-attached bars, contradicting the long-standing tenet that palaeoflows nearly orthogonal to the dip azimuth of large-scale inclined strata are indicative of sinuous, single-thread palaeochannels. Only Δf values significantly higher (>140°) or lower (<60°) than 90°discriminate mid-channel and bank-attached fluvial bars. Comparisons between Δf values and bar-accretionary styles suggest that mid-channel bars formed by high-peak and low-peak variable discharge rivers tend to preserve axially and laterally accreting deposits, respectively. Nearly orthogonal divergence angles are found in bank-attached bars irrespective of peak-discharge variability. While stressing that analyses akin to the one presented here are to be complemented with additional sedimentological information from high-quality outcrops, this study proposes a new, quantitative, approach to better distinguish fluvial bars, and hence possibly the planform pattern of associated channel bodies, from sedimentary successions. In particular, the data show that a reliable distinction between mid-channel and bank-attached bars should be based on comprehensive palaeocurrent and architectural information from various portions of preserved bar bodies, and that inferences based on limited datasets should be considered with caution.

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“…Although rivers with high suspended load and seasonal discharge can produce mud‐rich and cyclically‐organized deposits (Jablonski & Dalrymple, 2016; Johnston & Holbrook, 2019; Simon et al ., 2019), the abundance of mud and the rhythmic deposition are commonly considered as a signature of tidal processes (Bridges & Leeder, 1976; Barwis, 1978; Boersma & Terwindt, 1981; De Mowbray, 1983; Terwindt, 1988; Kvale et al ., 1989; Tessier & Gigot, 1989; Choi et al ., 2004; Pearson & Gingras, 2006; Santos & Rossetti, 2006; Dalrymple & Choi, 2007; Hubbard et al ., 2011; Fustic et al ., 2012; Kvale, 2012; Croix & Dashtgard, 2014, 2015; Rossi et al ., 2017). In tidal environments, mud can occur: (i) as laminae which define sedimentary structures (Van Straaten, 1954; Reineck, 1970; Dalrymple et al ., 1991; Tessier, 1993; Choi, 2010, 2011; Martinius & Van den Berg, 2011); (ii) as layers (for example, fluid mud Harris et al ., 2004; Ichaso & Dalrymple, 2009; Longhitano et al ., 2012; Chen et al ., 2015); and (iii) as intervals within the inclined heterolithic stratification (Bridges & Leeder, 1976; Barwis, 1978; De Mowbray, 1983; Thomas et al ., 1987; Choi et al ., 2004, 2013; Fagherazzi et al ., 2004; Rebata‐H.…”

Section: Introductionmentioning

confidence: 99%

Sedimentology of a hypertidal point bar (Mont‐Saint‐Michel Bay, north‐western France) revealed by combining lidar time‐series and sedimentary core data

et al. 2021

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Intertidal meanders developed on salt marshes are known to expand and produce inclined heterolithic stratification rich in fine‐grained sediments and to bear evidence for rhythmic deposition in the upper part of the inner meander bend (i.e. the upper part of the point bar). This occurs because the lower point‐bar deposits are washed by strong currents, which remove mud drapes and develop discontinuous record of tidal cycles. Although these criteria are widely accepted, facies models for tidal point bars still lack a three‐dimensional perspective and overlook the along‐bend variability of sediment distribution. The present study focuses on a hypertidal point bar belonging to the upper‐intertidal domain of the Mont‐Saint‐Michel Bay (France), and it analyses the sedimentology of a 3D time‐framed accretionary package formed between 28 March 2012 and 29 November 2012 by means of lidar topographic data, geomorphological field surveys and sedimentological core data. To define the 3D time‐framed accretionary package, data from thirteen lidar (light detection and ranging) topographic surveys were used to create the point‐bar synthetic stratigraphy. Data show that over the study period the point bar expanded alternating deposition along its seaward and landward sides, pointing out the occurrence of depositional patterns more complex than a simple progressive expansion of the bend. The thickest deposits were accumulated in the point‐bar‐apex zone, where the largest amount of mud was also stored. High sediment accretion in the bend‐apex zone is ascribed to the development of low‐energy conditions due to flow and bed configuration. High accretion rate of the point‐bar‐apex zone promoted also a better preservation of rhythmites, which are almost missing from deposits accumulated along the point‐bar sides. This study remarks that preservation of mud and tidal rhythmites within intertidal‐point‐bar deposits is controlled, not only by their elevation with respect to the tidal range, but also by their location along the point bar.

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An exhumed fine‐grained meandering channel in the lower Permian Clear Fork Formation, north‐central Texas

Cited by 3 publications

References 61 publications

Evolution of a gradually abandoned Oligocene fluvial palaeovalley fill: Abu‐Roash area, north Western Desert, Egypt

Evolution of a gradually abandoned Oligocene fluvial palaeovalley fill: Abu‐Roash area, north Western Desert, Egypt

Distinguishing mid‐channel and bank‐attached fluvial bars by flow divergence: Implications for the interpretation of stratigraphic records

Sedimentology of a hypertidal point bar (Mont‐Saint‐Michel Bay, north‐western France) revealed by combining lidar time‐series and sedimentary core data

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