Morphological evolution of Cap Lopez Canyon (Gabon): Illustration of lateral migration processes of a submarine canyon

Biscara, Laurie; Mulder, Thierry; Hanquiez, Vincent; Marieu, Vincent; Crespin, Jean-Pierre; Braccini, E.; Garlan, Thierry

doi:10.1016/j.margeo.2013.04.014

Cited by 22 publications

(19 citation statements)

References 21 publications

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“…Submarine-channel initiation and incision is associated with periods of high sediment supply (Elliott, 2000;Smith et al, 2007;Conway et al, 2012;Biscara et al, 2013). The development of large entrenched submarine channel systems (i.e., valleys) like the Y channel system has been linked both to high sediment supply (Normark and Carlson, 2003) and to baselevel changes (McHargue et al, 2011;Sylvester et al, 2011Sylvester et al, , 2012.…”

Section: Architectural Response To Changing Sediment Supply and Calibermentioning

confidence: 99%

Rapid Adjustment of Submarine Channel Architecture To Changes In Sediment Supply

Jobe¹,

Sylvester²,

Parker³

et al. 2015

Journal of Sedimentary Research

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Changes in sediment supply and caliber during the last ~130 ka have resulted in a complex architectural evolution of the Y channel system on the western Niger Delta slope. This evolution consists of four phases, each with documented or inferred changes in sediment supply. Phase 1 flows created wide (1,000 m), low-sinuosity (1.1) channel forms with lateral migration and little to no aggradation. During Phase 2, the Y channel system began to aggrade, creating more narrow (300 m) and sinuous (1.4) channel forms with many meander cutoffs. This system was abandoned at ~ 130 ka, perhaps related to rapid relative sea-level rise during MIS (Marine Isotope Stage) 5. Phase 3 flows were mud-rich and deposited sediment on the outer bends of the channel form, resulting in the narrowing (to 250 m), straightening (to a sinuosity of 1.22), and aggradation of the Y channel system. Renewed influx of sand into the Y channel system occurred with Phase 4 at ~ 50 ka, during MIS 3 sea-level fall. The onset of Phase 4 is marked by the initiation of the Y′ tributary channel, which re-established sand deposition in the Y channel system. Flows entering the Y channel from the Y′ channel were underfit, resulting in inner levee deposition that is most prevalent on outer banks, acting to further straighten (1.21) and narrow (to 200 m wide) the Y channel. The inner levees accumulated quickly as the flows sought equilibrium, with deposition rates > 200 cm/ky. Marked by the presence of the last sand bed, abandonment occurred at ~19 ka in the Y channel and ~15 ka in the Y′ channel and is likely related to progressive abandonment due to shelf-edge delta avulsion and/or progressive sea level rise associated with Melt Water Pulse 1-A. The muddy, 5-meter-thick Holocene layer has thickness variations that mimic those seen in the sandy part of Phase 4, suggesting that dilute, muddy flows continue to affect the modern Y channel system. This unique dataset allows us to unequivocally link changes in submarine channel architecture to variations in sediment supply and caliber. Changes in the updip sediment routing system (i.e. the channel "plumbing") are shown to have profound implications for submarine channel architecture and reservoir connectivity.

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Section: Architectural Response To Changing Sediment Supply and Calibermentioning

confidence: 99%

Rapid Adjustment of Submarine Channel Architecture To Changes In Sediment Supply

Jobe¹,

Sylvester²,

Parker³

et al. 2015

Journal of Sedimentary Research

View full text Add to dashboard Cite

show abstract

“…The absence of a sediment source indicates that these submarine canyons are currently remobilizing sediments already present within them or originating from the erosion of the canyons themselves. There is no new sediment supplied to these systems from the shelf as generally observed in active submarine canyons (Kudrass et al, 1998;Lewis and Barnes, 1999;Kripounoff et al, 2009;Biscara et al, 2013). Non deposition explains the "washed-out" surface observed at the head of the canyons where sediments are constantly being remobilized downslope without further input (Fig.…”

Section: Source Of Sedimentsmentioning

confidence: 87%

“…In recent years, the advances in high-resolution multibeam bathymetric surveys have allowed to increase the detail of studies on sedimentary processes along submarine canyons (Lastras et al, 2009(Lastras et al, , 2011Babonneau et al, 2013;Biscara et al, 2013). In these systems, triggers of submarine gravity flows were identified based on morphological features observed and described at canyon heads (García-García et al, 2012;Hill, 2012;Hughes Clarke et al, 2014), while bedforms were imaged and associated with certain types of sediment gravity flows (Puig et al, 2008;Paull et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Morphodynamics in sediment-starved inner-shelf submarine canyons (Lower St. Lawrence Estuary, Eastern Canada)

et al. 2014

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“…We also need to consider that turbidity currents in submarine channels only last for a few hours or days; therefore, these estimates for erosion rates and shear stresses are long-term averages and erosion rates during individual events must be one or two orders of magnitude larger. Repeat bathymetric surveys of active systems suggest that channel erosion can be surprisingly extensive and fast and these long-term and short-term incision rates are not unreasonable (Conway et al, 2012;Biscara et al, 2013). Furthermore, the overall morphology and stratigraphy of the modeled channel system does not depend on the exact values of the erosion rates; instead, they are driven by the relative magnitudes of the lateral and vertical rates of movement.…”

Section: Description Of Numerical Modelmentioning

confidence: 99%

“…This results in actual migration rates of up to 2.7 m/year. These values are relatively large, but not uncommon in rivers (e.g., Nanson and Hickin, 1986;Constantine et al, 2014); and the few observations from modern submarine channels and canyons suggest that such high lateral migration rates may be characteristic of active deepwater systems (Conway et al, 2012;Biscara et al, 2013). For modeling vertical incision, we use the simplest erosion law that relates vertical incision rate to mean shear stress acting on the channel thalweg :…”

Section: Description Of Numerical Modelmentioning

confidence: 99%

Development of cutoff-related knickpoints during early evolution of submarine channels

Sylvester¹,

Covault²

2017

Preprint

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Submarine channels are often thought of as having relatively simple geometries, with significant alongchannel morphologic and stratigraphic continuity. Using high-resolution seismic reflection data from offshore Angola and a kinematic model of channel evolution, we present evidence that channels on the seafloor can develop slope variability as a result of meander cutoff events. When cutoffs develop, the shortened flow paths produce locally steep gradients, thus initiating knickpoints. Waves of knickpoint retreat and the related channel incision explain the occurrence of terraces and associated remnant channel deposits above the youngest channel thalweg. The simple processes of meander cutoff followed by knickpoint retreat are intrinsic to submarine channels and result in significant morphologic variability, erosion, and stratigraphic complexity, without any external forcing. These insights highlight the early evolution of submarine channels, a phase with a record that is commonly fragmented or completely absent as a result of subsequent erosion, and allow a better understanding of the autogenic controls on deep-marine stratigraphy.

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Morphological evolution of Cap Lopez Canyon (Gabon): Illustration of lateral migration processes of a submarine canyon

Cited by 22 publications

References 21 publications

Rapid Adjustment of Submarine Channel Architecture To Changes In Sediment Supply

Rapid Adjustment of Submarine Channel Architecture To Changes In Sediment Supply

Morphodynamics in sediment-starved inner-shelf submarine canyons (Lower St. Lawrence Estuary, Eastern Canada)

Development of cutoff-related knickpoints during early evolution of submarine channels

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