Multiple terraces within the deep incised Zaire Valley (ZaïAngo Project): are they confined levees?

Babonneau, Nathalie; Savoye, Bruno; Cremer, Michel; Bez, M.

doi:10.1144/gsl.sp.2004.222.01.06

Cited by 62 publications

(85 citation statements)

References 30 publications

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“…Because the geometries and facies architecture at Bonga are similar to the Y channel system, invoking a similar style of evolution at Bonga is tempting. However, the creation of inner levees or terraces can be achieved by multiple processes, including sediment supply variations (this study), channel-form migration (Deptuck et al, 2007;Sylvester et al, 2011), thalweg incision (Babonneau et al, 2004), and channel-bank slumping (Kenyon et al, 1995). The data are not of sufficient resolution to determine which process is dominant at Bonga.…”

Section: Application To Prediction and Characterization Of Hydrocarbomentioning

confidence: 87%

“…This is especially difficult to do in outcrop and core studies, where shale drapes and erosional surfaces are often interpreted as signs of channel abandonment and reoccupation, but, due to the lack of three-dimensionality and fine-scale age control, it is impossible to verify whether that is indeed the case. The integration of high-resolution bathymetry, high-resolution "chirp" seismic reflection surveys, and core data has provided new insights into the architecture and evolution of submarine channel systems (Pirmez et al, 1997;Gervais, 2002;Babonneau et al, 2002Babonneau et al, , 2004Babonneau et al, , 2010Paull et al, 2011). The absence, however, of three-dimensional (3D) seismic reflection data often hampers the understanding of the 3D complexity of these systems.…”

Section: Introductionmentioning

confidence: 99%

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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: Application To Prediction and Characterization Of Hydrocarbomentioning

confidence: 87%

Section: Introductionmentioning

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

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“…2d). A terrace is defined as a topographic flat bordering a channel within the channel belt (Babonneau et al, 2004). Terraces are generated by multiple mechanisms such as entrenchment, bank failure, deposition of inner/internal levees, lateral channel migration, and meander cut-offs (Babonneau et al, 2004;Deptuck et al, 2003;Hansen et al, 2015).…”

Section: Terminologymentioning

confidence: 99%

“…A terrace is defined as a topographic flat bordering a channel within the channel belt (Babonneau et al, 2004). Terraces are generated by multiple mechanisms such as entrenchment, bank failure, deposition of inner/internal levees, lateral channel migration, and meander cut-offs (Babonneau et al, 2004;Deptuck et al, 2003;Hansen et al, 2015). The term channel belt is used in multiple studies (Deptuck et al, 2003;Posamentier, 2003;Catterall et al, 2010;Kane and Hodgson, 2011;Gamberi et al, 2013;Hansen et al, 2015).…”

Section: Terminologymentioning

confidence: 99%

“…The valley is formed by lateral migration and vertical stacking of a single channel element (e.g. Samuel et al, 2003;Deptuck et al, 2003;Babonneau et al, 2004;Kolla, 2007;Janocko et al, 2013), and has a composite erosional surface consisting of a valley base and adjacent valley walls (erosional fairway sensu Deptuck et al, 2003;Catterall et al, 2010; master erosion/incision surface sensu Gee et al, 2007; channel-belt erosion surface sensu Kane and Hodgson, 2011; bounding erosion surface sensu Hansen et al, 2015) (Fig. 2e).…”

Section: Terminologymentioning

confidence: 99%

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Quantitative seismic geomorphology of a submarine channel system in SE Brazil (Espírito Santo Basin): Scale comparison with other submarine channel systems

Qin

Alves

Constantine

et al. 2016

Marine and Petroleum Geology

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Detailed morphological analyses of a Pleistocene-Holocene submarine channel system in terms of its hierarchical framework, were carried out using a 3D seismic volume from offshore Espírito Santo, SE Brazil. The channel morphology shows marked variations, with five segments (Segments a to e) being identified along its full length. For example, the cross-sectional area of the channel decreases by a factor of 70 from Segment a to Segment c, and is then followed by a nearly four-fold increase from Segment c to Segment d. The significant changes in channel morphology relate to temporal and spatial variations in flow volume within the channel. In the same channel system, the valley reveals three distinct segments (Segments A to C), with similar aspect ratios but marked variations in morphology along the valley distance. Valley morphological changes are chiefly affected by erosional processes. Segment B is characterised by the largest valley-base width, valley width, and cross-sectional area compared to the other two segments. Valley enlargement in Segment B results from relatively high degrees of lateral channel migration and associated cut bank erosion, leading to the widening of the valley, especially the valley base. In Segment C, the valley is characterised by inner bank erosion in the form of shallow-seated mass failures, which only enlarged the upper part of the valley wall. The spatial variations in both channel and valley morphology documented here suggest an important role of local factors (e.g. salt diapirs, tributaries, overbank collapse) in the development of channel systems. Hence, the morphological analyses developed in this work provide an effective tool for studying channels and valleys on continental slopes around the world.

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Channel incision into a submarine landslide on a Carboniferous basin margin, San Juan, Argentina: Evidence for the role of knickpoints

Allen

Gomis‐Cartesio

Hodgson

et al. 2022

The Depositional Record

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Emplacement of submarine landslides, or mass-transport deposits, can radically reshape the physiography of continental margins, and strongly influence subsequent sedimentary processes and dispersal patterns. Typically, progressive healing of the complicated relief generated by the submarine landslide occurs prior to progradation of sedimentary systems. However, subsurface and seabed examples show that submarine channels can incise directly into submarine landslides.Here, the evolution of a unique exhumed example of two adjacent, and partially contemporaneous, submarine channel-fills is documented. The channels show deep incision (>75 m), and steep lateral margins (up to 70°), cut into a >200 m thick submarine landslide. The stepped basal erosion surface, and multiple terrace surfaces, are mantled by clasts (gravels to cobbles) reflecting periods of bedloadderived sedimentation, punctuated by phases of downcutting and sediment bypass. The formation of multiple terrace surfaces in a low aspect ratio confinement is consistent with the episodic migration of knickpoints during entrenchment on the dip slope of the underlying submarine landslide. Overlying sandstone-rich channel-fills mark a change to aggradation. Laterally stacked channel bodies coincide with steps in the original large-scale erosion surface, recording widening of the conduit; this is followed by tabular, highly aggradational fill. The upper fill, above a younger erosional surface, shows an abrupt change to partially confined tabular sandstones with normally graded caps, interpreted as lobe fringe deposits, which formed due to down-dip confinement, followed by prograding lobe deposits. Overlying this, an up-dip avulsion induced lobe switching and back-stepping, and subsequent failure of a sandstone body up-dip led to emplacement of a sandstone-rich submarine landslide within the conduit. Collectively, this outcrop represents episodic knickpoint-generated incision, and later infill, of a slope adjusting to equilibrium. The depositional signature of knickpoints is very

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Multiple terraces within the deep incised Zaire Valley (ZaïAngo Project): are they confined levees?

Cited by 62 publications

References 30 publications

Rapid Adjustment of Submarine Channel Architecture To Changes In Sediment Supply

Rapid Adjustment of Submarine Channel Architecture To Changes In Sediment Supply

Quantitative seismic geomorphology of a submarine channel system in SE Brazil (Espírito Santo Basin): Scale comparison with other submarine channel systems

Channel incision into a submarine landslide on a Carboniferous basin margin, San Juan, Argentina: Evidence for the role of knickpoints

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