Morphology of a delta prograding by bulk sediment transport

Kenyon, P. M.; Turcotte, D. L.

doi:10.1130/0016-7606(1985)96<1457:moadpb>2.0.co;2

Cited by 177 publications

(116 citation statements)

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“…Diffusion-based models of clinoform formation assume that sediment transport is a function of topographic slope [Kenyon and Turcotte, 1985;Flemings and Jordan, 1989;Jordan and Flemings, 1991;Thorne, 1995]. These models result in a clinoform geometry that resembles that in natural systems, but implicit in these models is the interpretation that sediment transport is a function of slope-driven processes, such as creep, sliding, and slumping [e.g., Kenyon and Turcotte, 1985].…”

Section: Existing Modelsmentioning

confidence: 99%

Clinoform development by advection‐diffusion of suspended sediment: Modeling and comparison to natural systems

Pirmez¹,

Pratson²,

Steckler³

1998

J. Geophys. Res.

199

228

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Abstract. Clinoforms are the building blocks of prograding stratigraphic sequences. These sigmoid-shaped surfaces can be found forming today on modem deltas. Sedimentation rate profiles over the clinoform surface of these deltas show low rates of sediment accumulation on both topset and bottomset regions, with a maximum accumulation rate on the upper foreset region. We present a model for the formation of clinoforms that relies on the interpretation of modem clinoform sedimentation as a result of the distribution of shear stresses at the mouth of a river. Model clinoform surfaces are generated using an equation for the conservation of suspended sediment concentration, together with a conservation of fluid equation for simple time-averaged flow velocity fields. In the model, suspended sediment is advected horizontally into a basin, and gravitational settling of sediment particles is counteracted by vertical turbulent diffusion. In shallow water, shear stresses are too large to allow deposition, and sediment bypasses the topset region. With increasing water depth, near-bed shear stresses decrease, and sediment is allowed to deposit at the foreset region, with gradually decreasing rates toward deeper water. This sedimentation pattern leads to progradation of the clinoform surfaces through time. The clinoform surfaces produced by the model capture the fundamental morphological characteristics of natural clinoforms. These include the gradual slope rollover at the topset and bottomset, steeper foreset slopes with increased grain size, and an increase in foreset slope through time as clinoforms prograde into deeper water. Because the parameters controlling the model clinoforms have a direct relation to physical quantities that can be measured in natural systems, the model is an important step toward unraveling the physical processes associated with these deposits.

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Section: Existing Modelsmentioning

confidence: 99%

Clinoform development by advection‐diffusion of suspended sediment: Modeling and comparison to natural systems

Pirmez¹,

Pratson²,

Steckler³

1998

J. Geophys. Res.

199

228

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“…The poor sorting and weak clast imbrication within foreset beds reflect deposition through avalanching, highly concentrated debris flows and bedload deposition down the delta face [52,72]. The upward fining sequence recorded in LF3b from Tasiussaq is common sedimentological characteristics of delta foresets [20], representing retreat of the ice margin.…”

Section: Lfa3mentioning

confidence: 99%

“…The fine-grained planar-stratified deposits of LF3a are interpreted as bottomsets of a delta, representing low-energy fluviodeltaic sedimentation [38,61], deposited by suspended load sediment settling in front of an advancing delta [38,52,61]. The ubiquitous macroscopic plant remains are likely to have been introduced from upstream regions through reworking of pre-existing vegetation during glacial advance.…”

Section: Lfa3mentioning

confidence: 99%

The glacial history of the southern Svartenhuk Halvø, West Greenland

Lane

Roberts

Cofaigh

et al. 2015

Arktos

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This paper presents a new, detailed geomorphological and sedimentological appraisal of the southern Svartenhuk Halvø, a remote area of West Greenland that has only been subjected to limited geomorphological and sedimentological research. Despite this, it is of importance as several studies have suggested it remained an ice-free enclave during the Last Glacial Maximum. This previous work, based on biostratigraphic and chronological evidence, has provided evidence for the 'Svartenhuk Marine Event', a period of ice free conditions and marine deposition into a higher than present relative sea-level during the previous interglacial (MIS 5a-e). This has been correlated to other interglacial deposits in West Greenland. New geomorphological and sedimentological investigations from this study present compelling arguments for the glaciation of southern Svartenhuk Halvø by valley glaciers and mountain ice caps, questioning the status of this peninsula as an ice-free enclave. Ice directional indicators and clast lithological results suggest ice covering Svartenhuk Halvø was sourced from the higher altitude interior of the peninsula and expanded to the present coastline. In a number of valleys, sedimentological evidence points to at least two glacial advances with subglacial till production through the reworking of glaciomarine sediments, and ice contact and glacier-fed delta deposition during phases of ice retreat. The geomorphological and sedimentological context of the sediments (Gilbert type deltas), coupled with evidence for eskers and kettled/pitted delta surfaces, suggests these features formed under glacial and not interglacial conditions. This is supported by new radiocarbon dates which suggest outlet glacier advance and retreat across the area towards the end of MIS 3 and possibly into the Early Holocene. Svartenhuk Halvø was not overrun by the main Greenland Ice Sheet during the last glacial cycle, but the development of an independent ice cap and local outlet glaciers across this region may have been instrumental in determining the dynamic evolution of the Uummannaq ice stream onset zone during the last glacial cycle.

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“…Diffusion models have been used by many authors to simulate sediment erosion, transport, and deposition in deltaic environments. In such models the assumptions are made that the rate of sediment transport depends linearly on bathymetric slope and that the sediment transport is in the downslope direction [e.g., Kenyon and Turcotte, 1985;Driscoll and Karner, 1999]. This results in an increase in the height of a surface if more sediment is delivered to a certain location than is removed.…”

Section: Slope Failurementioning

confidence: 99%

Three‐dimensional numerical modeling of coarse‐grained clastic deposition in sedimentary basins

Ritchie¹,

Hardy²,

Gawthorpe³

1999

J. Geophys. Res.

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Abstract. A three-dimensional numerical model of clastic deposition in sedimentary basins is used to investigate the development of coarse-grained deltas in response to relative sea level changes. The model incorporates fully three-dimensional sediment delivery and deposition, together with incised channel formation and slope failure. A combined random-walk/steepestdescent algorithm is used to simulate sediment delivery from a drainage basin outlet to the depositional shoreline, together with a nonlinear three-dimensional diffusion equation for modeling slope-dependent sediment erosion, transport, and deposition. When sediment channels (transport pathways) are out of a specified grade, advective erosion occurs, thereby increasing the total sediment supply delivered to the basin. Multiple sediment sources into a basin can be simulated, together with tectonic subsidence and eustatic sea level changes. The model results presented display many of the key features observed in both modern and ancient coarse-grained deltas. During periods of slowly changing and high relative sea level (highstands), a broad delta front progrades approximately radially away from the sediment source. Conversely, incised channels are developed during rapid falls of relative sea level, leading to localized deposition of deltaic lobes at the mouths of these channels. The incised channels initiate at the exposed delta front and propagate backward toward the sediment source. The rate of growth of incised channels is shown to be an important control on delta morphology, sediment distribution, and lowstand lobe size and location. Lobes are particularly well developed during periods of slowly changing low relative sea level (lowstands). Periods of rapid rise of relative sea level lead to flooding and infilling of incised channel systems and a rapid landward shift in deposition (transgressions). Incised channels and delta lobes are best developed in a model where tectonic subsidence is similar to that expected for hanging-wall-sourced deltas in extensional half-graben settings. In contrast, both channels and lobes are less well developed in a model where tectonic subsidence is similar to that expected for footwall-sourced deltas in such settings. Many of the features developed in the models are, by their nature, three dimensional, and two-dimensional analysis of the model results can lead to erroneous interpretations of the causes of along-strike variability. These aspects of sequence variability have important implications for the application of the sequence stratigraphic methodology to many sedimentary basins.

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Morphology of a delta prograding by bulk sediment transport

Cited by 177 publications

References 0 publications

Clinoform development by advection‐diffusion of suspended sediment: Modeling and comparison to natural systems

Clinoform development by advection‐diffusion of suspended sediment: Modeling and comparison to natural systems

The glacial history of the southern Svartenhuk Halvø, West Greenland

Three‐dimensional numerical modeling of coarse‐grained clastic deposition in sedimentary basins

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