Monsoon control on channel avulsions in the Late Quaternary Congo Fan

Picot, M.; Marsset, Tania; Droz, Laurence; Dennielou, Bernard; Baudin, François; Hermoso, Michaël; Rafélis, Marc de; Sionneau, Thomas; Cremer, Michel; Laurent, Dimitri; Bez, M.

doi:10.1016/j.quascirev.2018.11.033

Cited by 37 publications

(63 citation statements)

References 103 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As an example, the lack of microplastic particles identified at the deepsea Congo Fan was viewed as anomalous due to the presence of major industrial cities on the Congo River (Van Cauwenberghe et al, 2013), but no information is provided about whether the part of the fan sampled was active (i.e., subject to recent turbidity current activity or near-bed oceanographic currents), nor regarding the grain size of the host sediment. Previous studies have demonstrated that, while much of the Congo canyon, deep-sea channel and fan system is a highly active conduit for sediment and organic carbon transport in the present day (Khripounoff et al, 2003;Azpiroz-Zabala et al, 2017), not all of the deep sea distributary networks are active (Picot et al, 2019). Thus, without any detailed information on the seafloor sediments and specific location within the submarine channelfan system, it is challenging to determine how representative one core location is for an entire system.…”

Section: In Which Physiographic Domains Have Microplastics Been Docummentioning

confidence: 99%

Dispersion, Accumulation, and the Ultimate Fate of Microplastics in Deep-Marine Environments: A Review and Future Directions

2019

View full text Add to dashboard Cite

Kane and Clare Microplastics in Deep-Marine Environments environments, their distribution and ultimate fate, and the implications that these have for benthic ecosystems. The dispersal of anthropogenic across the sedimentary systems that cover Earth's surface has important societal and economic implications. Sedimentologists have a key, but as-yet underplayed, role in addressing, and mitigating this globally significant issue.

show abstract

Section: In Which Physiographic Domains Have Microplastics Been Docummentioning

confidence: 99%

Dispersion, Accumulation, and the Ultimate Fate of Microplastics in Deep-Marine Environments: A Review and Future Directions

2019

View full text Add to dashboard Cite

show abstract

“…As observed in many turbidite systems, only one channellevees-lobe continuum is active at any given time (Droz et al, 1996;, the abandonment of the active channel is achieved through avulsion of the feeder channel that can be a gradual but generally non-reversible process (Droz et al, 2003;Picot et al, 2019). More than 80 inactive palaeo-channel-levees-lobe systems have been identified in the Quaternary Congo turbidite system (Picot et al, 2016;Savoye et al, , 2009.…”

Section: Submarine Turbidite Systemmentioning

confidence: 99%

“…Additionally, numerous sedimentological and organic geochemical data were obtained during the shore-based studies on the 145 sediment cores collected in different parts of the Congo turbidite system, from the canyon head to the terminal lobe complex, by ca. 5000 m of water depth (Droz et al, 1996(Droz et al, , 2003Gervais et al, 2001;Babonneau, 2002;Babonneau et al, 2002Babonneau et al, , 2004Babonneau et al, , 2010Ferry et al, 2004;Migeon et al, 2004;Bonnel, 2005;Treignier, 2005;Marsset et al, 2009;Rabouille et al, 2009Rabouille et al, , 2017aRabouille et al, , 2017bBaudin et al, 2010Baudin et al, , 2017aBaudin et al, , 2017bPicot, 2015;Stetten et al, 2015;Picot et al, 2016Picot et al, , 2019Croguennec et al, 2017;Méjanelle et al, 2017;Pastor et al, 2017;Pozzato et al, 2017;Schnyder et al, 2017;Taillefert et al, 2017). The resulting data allows a good description and understanding of the entire Congo turbidite system.…”

Section: Summary Of Recent Studies On the Congo Deep-sea Fanmentioning

confidence: 99%

“…The geochronologies and sediment accumulation rates of 43 cores were determined by a combination of 14 C, 210 Pb and/or 137 Cs (Savoye et al, 2009;Stetten et al, 2015;Rabouille et al, 2017b;Picot et al, 2019). These cores were collected at water depths ranging from 502 to 5178 m. These cores are located on continental slope adjacent to the canyon, on terraces inside the canyon, on Figure 3.…”

Section: Seabed Chronologies and Sedimentation Ratesmentioning

confidence: 99%

See 1 more Smart Citation

Routing of terrestrial organic matter from the Congo River to the ultimate sink in the abyss: a mass balance approach (André Dumont medallist lecture 2017)

Baudin

Dennielou

2020

Geol. Belg.

Self Cite

View full text Add to dashboard Cite

We address the role of the Congo River sediment dispersal in exporting and trapping organic carbon into deep offshore sediments. Of particular interest is the Congo submarine canyon, which constitutes a permanent link between the terrestrial sediment sources and the marine sink. The Congo River delivers an annual sediment load of ~40 Tg (including 2 Tg of C) that feed a mud-rich turbidite system. Previous estimates of carbon storage capacity in the Congo turbidite system suggest that the terminal lobe complex accounts for ~12% of the surface area of the active turbidite system and accumulates ~18% of the annual input of terrestrial particulate organic carbon exiting the Congo River. In this paper, we extend the approach to the whole active turbidite depositional system by calculating an average burial of terrestrial organic matter in the different environments: canyon, channel, and levees. We estimate that between 33 and 69% of terrestrial carbon exported by the Congo River is ultimately trapped in the different parts of turbidite system and we evaluate their relative efficiency using a source to sink approach. Our carbon budget approach, which consider annual river discharge versus offshore centennial accumulation rates, indicates that about half of the total particulate organic matter delivered yearly by the Congo River watershed escapes the study area or is not correctly estimated by our deep offshore dataset and calculations.

show abstract

“…In submarine channel settings, no historical avulsions have been observed or documented, and both the setup and triggering mechanisms are poorly constrained. Most work has focused not on the setup, but instead on interpreting triggers, which include flow-overspill and flow-stripping (Piper and Normark, 1983;Fildani et al, 2006), channel-floor aggradation (Kolla, 2007;Armitage et al, 2012), levee failure by mass-wasting (Flood et al, 1991;Brunt et al, 2013), mass-transport deposition/erosion (Ortiz-Karpf et al, 2015), and climate cyclicity (Picot et al, 2019). Avulsion triggers are difficult to predict due to their dependence on local factors and their opportunistic nature (Slingerland and Smith, 2004); however, the setup can easily be measured and constrained using the abundant seafloor, seismic reflection, and core data that documents Quaternary submarine channel avulsions (e.g., Pirmez and Flood, 1995;Manson, 2009 for the Amazon, Torres et al, 1997 for the Rhone).…”

Section: Introductionmentioning

confidence: 99%

Comparing Aggradation, Superelevation, and Avulsion Frequency of Submarine and Fluvial Channels

et al. 2020

View full text Add to dashboard Cite

Constraining the avulsion dynamics of rivers and submarine channels is essential for predicting the distribution of sediment, organic matter, and pollutants in alluvial, deltaic, and submarine settings. We create a geometric channel-belt framework relating channel, levee, and floodplain stratigraphy that allows comparative analysis of avulsion dynamics for rivers and submarine channels. We utilize 52 channel-overbank crosssections within this framework to provide avulsion criteria for submarine channels, and how they differ from rivers. Superelevation and a new channel-floodplain coupling metric are two key parameters that control channel-belt thickness in both rivers and submarine channels. While rivers only superelevate 1 channel depth above the floodplain prior to avulsion, submarine channels are more stable during aggradation, with superelevation values commonly > 3 channel depths. Additionally, channel-floodplain coupling in rivers is often weak, with floodplain aggradation negligible compared to channel aggradation, making rivers avulsion-prone. However, floodplain aggradation is more significant for submarine channels, resulting in stronger channel-floodplain coupling and thus a decreased potential for avulsion. The combination of enhanced superelevation and strong channel-floodplain coupling results in submarine channel-belts that can be as thick as ∼10 channel depths, while fluvial channel belts are limited to 2 channel depths. Submarine channels are more stable because turbidity currents have ∼50x lower density contrast between flow and ambient fluid as compared to rivers. This density contrast creates far less potential energy for avulsion, despite the much greater relief of submarine levees compared to fluvial levees. The modern Amazon submarine channel showcases this stability, with a channel belt that is ∼5 channel-depths thick for more than 400 streamwise km, which is more than twice the superelevation that a river is capable of. We interpret that enhanced floodplain aggradation and levee aggradation (and thus superelevation) in submarine channel belts are promoted by unique submarine flow characteristics, including turbidity current overspill, flow-stripping, and hemipelagic processes. We emphasize that rivers and submarine channels display very different avulsion dynamics and frequencies, profoundly affecting the stratigraphic architecture of channel-belt and downstream distributary deposits.

show abstract

Monsoon control on channel avulsions in the Late Quaternary Congo Fan

Cited by 37 publications

References 103 publications

Dispersion, Accumulation, and the Ultimate Fate of Microplastics in Deep-Marine Environments: A Review and Future Directions

Dispersion, Accumulation, and the Ultimate Fate of Microplastics in Deep-Marine Environments: A Review and Future Directions

Routing of terrestrial organic matter from the Congo River to the ultimate sink in the abyss: a mass balance approach (André Dumont medallist lecture 2017)

Comparing Aggradation, Superelevation, and Avulsion Frequency of Submarine and Fluvial Channels

Contact Info

Product

Resources

About