Sedimentary structures of combined flow deposits from the shoreface-connected ridges along the central Dutch coast

Meene, Jan W.H van de; Boersma, J. R.; Terwindt, Joost H. J.

doi:10.1016/0025-3227(95)00074-7

Cited by 51 publications

(27 citation statements)

References 25 publications

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“…Hence, the sandbank morphology evolved from a slightly arcuate shape in 1824 to a sigmoid shape in 2000. This evolution shows similarities with the first steps of the sandbank multiplication model proposed by Caston (1972) for some open shelf sand ridges of the North Sea (van de Meene et al, 1996). Century timescale changes in tidal channels flanking the Longe de Boyard Sandbank evidenced sediment filling of the Eastern Channel, which reached 6 m locally, and a northeastward lateral progradation of the sandbank, resulting in a reduction of the cross section area of about 15%.…”

Section: Bathymetric Resultsmentioning

confidence: 55%

Multi time-scale evolution of a wide estuary linear sandbank, the Longe de Boyard, on the French Atlantic coast

et al. 2008

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Section: Bathymetric Resultsmentioning

confidence: 55%

Multi time-scale evolution of a wide estuary linear sandbank, the Longe de Boyard, on the French Atlantic coast

et al. 2008

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“…The data reveal the mean grain size pattern is approximately 90° out of phase with topography, with the coarsest sand on the landward flank (upcurrent), and the finest sand on the seaward (downcurrent) flank. An exception to this very consistent pattern in the mean grain size, as observed on different shelves, concerns the shoreface‐connected ridges along the central Dutch coast (southern North Sea) [ Van de Meene et al , 1996]. No marked spatial variation in the mean grain size across the ridge topography is found, except for a weak tendency toward a better sorting (smaller standard deviations) at the crests of the ridges.…”

Section: Discussionmentioning

confidence: 96%

Effect of grain size sorting on the formation of shoreface‐connected sand ridges

Walgreen¹

2003

J. Geophys. Res.

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[1] Field data of shoreface-connected ridges show persistent spatial variations of mean grain size over the bed forms. In the shore-normal direction, the profiles of bottom topography and mean grain size are approximately 90°out of phase. To investigate the mechanisms responsible for the observed grain size distribution and the influence of sediment sorting on the temporal and spatial characteristics of shoreface-connected ridges, a model is developed and analyzed. A linear stability analysis of an alongshore uniform basic state (describing a storm-driven flow on a microtidal inner shelf) with respect to small bottom perturbations is carried out. The transport of nonuniform sediment is described by formulations for both bed load and suspended load, both of which account for dynamic hiding effects. A one-layer model for the bed evolution and a bottom friction term, which depends on the grain size, are used. The initial formation of the ridges is studied for a bimodal sediment mixture. The results of the model indicate that the phase shift between bed topography and mean grain size for shoreface-connected ridges is due to the selective transport via suspended load of grains with different sizes. A net stabilizing effect on the growth of bed forms and enhanced migration are predicted, caused by the bimodal character of the sediment. The wavelengths of the bed forms are only slightly affected. Including a tidal current or a grain size dependent formulation for the bottom friction has no effect on the results. A physical explanation for the model results is also given.

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“…Slump folds and syn-sedimentary faults, boudins are common. Interpretation: The cross-stratification style and their dimensions indicate a combined-flow origin (Arnott and Southard 1990;Van de Meene et al 1996;Myrow et al 2002), and the presence of hummocky cross-stratification and quasi-planar lamination suggests deposition from storm-generated flows under transitional upper-stage plane bed conditions (Arnott 1993). Superimposition of unidirectional currents on the storm-generated oscillatory flow resulted in a combined-flow structure that could sustain low-relief unidirectionally migrating bedforms superposed on asymmetric hummocky strata instead of typical, symmetrical, hummocky cross-stratification.…”

Section: 3a Facies-3a (Storm-induced Combined-flow Deposits)mentioning

confidence: 98%

Pattern of sedimentation during the Late Paleozoic, Gondwanaland glaciation: An example from the Talchir Formation, Satpura Gondwana basin, central India

Chakraborty

Ghosh

2008

J Earth Syst Sci

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The Talchir Formation of Permian age is the lowermost lithostratigraphic unit of the Indian Gondwana successions preserving a record of the Late Paleozoic glaciation that affected the whole Gondwanaland. The formation unconformably overlies the Precambrian basement in all the Gondwana basins of India, and marks initiation of sedimentation after a long hiatus since the Proterozoic. The Talchir Formation of the Satpura Gondwana basin of central India shows features diagnostic of deposition under glacial regime such as the presence of diamictites, boulder pavements, bedding plane striation, faceted/striated gravels, bullet-shaped clasts, dropstone, cryoturbation, etc. The Talchir strata of the Satpura basin, in addition to tidal signatures, contain marine bivalve and trace fossils. A proglacial marine environment is thus inferred for their deposition. The dominant lithologies are conglomerate, pebbly sandstone, sandstone and shale with little limestone, which can be classified into the following major facies:• matrix-supported conglomerate, • clast-supported conglomerate, • cross-stratified, channel form pebbly sandstone, • hummocky, swaley or low-angle cross-stratified pebbly and non-pebbly sandstone, • turbidite/tempestite sheet sandstone, • massive to fissile, green to black claystone with carbonate layers and nodules.The conglomerates are interpreted as deposits of a spectrum of sub-aqueous sediment gravity flows including debris flow, hyperconcentrated/concentrated density flow and grain flow. The crossstratified pebbly sandstone bodies, on the other hand, represent braidplain delta deposits of glacial outwash origin. Hummocky, swaley, low-angle cross-stratified sediment bodies were deposited by storm-generated combined flows in a shoreface setting. In contrast, the sheet sandstone bodies are products of turbidity currents and storm-induced density currents in an inner shelf setting below fair weather wave base. The claystone facies is interpreted as a product of suspension fallout from hypopycnal sediment plumes in the outer shelf domain below storm wave base. All the lithofacies described above occur repetitively in the succession. Three facies-associations have been recognized in the Talchir Formation, representing ice-contact fandelta, outwash braidplain delta and a virtually ice-free, non-deltaic open marine realm. The different marine facies of the Talchir Formation define a number of shallowing-upward packages, which are arranged in the succession with a retrogradational trend to result in an overall fining-and deepening-upward succession. The overlying coal-bearing Barakar Formation has been interpreted to have formed in a tide-wave influenced deltaic setting with a marine, prodeltaic part. The strata that are transitional between Talchir and Barakar Formations show preservation of abundant plant materials suggesting gradual warming. The three facies-associations of the Talchir Formation also point towards progressive decrease in the intensity of glacial activity, inducing changes in the paleogeography ...

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Sedimentary structures of combined flow deposits from the shoreface-connected ridges along the central Dutch coast

Cited by 51 publications

References 25 publications

Multi time-scale evolution of a wide estuary linear sandbank, the Longe de Boyard, on the French Atlantic coast

Multi time-scale evolution of a wide estuary linear sandbank, the Longe de Boyard, on the French Atlantic coast

Effect of grain size sorting on the formation of shoreface‐connected sand ridges

Pattern of sedimentation during the Late Paleozoic, Gondwanaland glaciation: An example from the Talchir Formation, Satpura Gondwana basin, central India

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