Two fundamentally different types of submarine canyons along the continental margin of Equatorial Guinea

Jobe, Zane R.; Lowe, Donald R.; Uchytil, Steve

doi:10.1016/j.marpetgeo.2010.07.012

Cited by 163 publications

(88 citation statements)

References 98 publications

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“…Examples include potential economic deposits located off West Africa (Jobe et al, 2011) and the Campos Basin located on the continental slope of Brazil, which is currently under production by PETROBRAS and other companies (Gorini et al, 1998;Day, 2002). In Australia, an assessment was made by Harris et al (2007) of the seafloor features most characteristic of offshore oil and gas leases.…”

Section: Oil and Gas Exploitationmentioning

confidence: 99%

Ecological Role of Submarine Canyons and Need for Canyon Conservation: A Review

et al. 2017

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Submarine canyons are major geomorphic features of continental margins around the world. Several recent multidisciplinary projects focused on the study of canyons have considerably increased our understanding of their ecological role, the goods, and services they provide to human populations, and the impacts that human activities have on their overall ecological condition. Pressures from human activities include fishing, dumping of land-based mine tailings, and oil and gas extraction. Moreover, hydrodynamic processes of canyons enhance the down-canyon transport of litter. The effects of climate change may modify the intensity of currents. This potential hydrographic change is predicted to impact the structure and functioning of canyon communities as well as affect nutrient supply to the deep-ocean ecosystem. This review not only identifies the ecological status of canyons, and current and future issues for canyon conservation, but also highlights the need for a better understanding of anthropogenic impacts on canyon ecosystems and proposes other research required to inform management measures to protect canyon ecosystems.

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Section: Oil and Gas Exploitationmentioning

confidence: 99%

Ecological Role of Submarine Canyons and Need for Canyon Conservation: A Review

et al. 2017

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“…5), and were likely initiated during undercutting of the channel-margin substrate. These features are "rotated channel-margin slides" (Sawyer et al, 2007;Jobe et al, 2011) and show progressive rotation on a listric fault surface with up to 150 m of offset (see marker horizon in Fig. 5) that indicate synsedimentary deformation.…”

Section: Evolution Of the Y Channel Systemmentioning

confidence: 99%

“…15) and modified by fluid expulsion, creating pockmarks and ridges (cf. Jobe et al, 2011). Downstream of the Y′ junction, the Y channel was active until 19 ka, when the entire Y channel system was abandoned.…”

Section: Phasementioning

confidence: 99%

“…A more recent example from the Canadian Grand Banks highlights the difference between submarine canyons fed by sand-and gravel-rich glacial outwash and those fed solely by muddy slope failures (Armitage et al, 2010). Jobe et al (2011) demonstrate that variations in sediment supply and grain-size distribution over millions of years have a clear impact on submarine canyon and channel architecture. Sediment supply, as in subaerial systems, must play a key role as well in the architectural evolution of submarine depositional 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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“…This model has been shown to explain canyon evolution in many margins around the world, e.g. Angolan (Gee et al, 2007); South African (Green et al, 2007); Equatorial Guinean (Jobe et al, 2011); Chilean (Laursen and Normark, 2002);…”

Section: Accepted M Manuscriptmentioning

confidence: 98%

Space-for-time substitution and the evolution of a submarine canyon–channel system in a passive progradational margin

et al. 2014

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Please cite this article as: Micallef, Aaron, Ribó, Marta, Canals, Miquel, Puig, Pere, Lastras, Galderic, Tubau, Xavier, Space-for-time substitution and the evolution of a submarine canyon-channel system in a passive progradational margin, Geomorphology (2014), doi: 10.1016/j.geomorph.2014.06.008 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT1 Manuscript submitted to Geomorphology:Space-for-time substitution and the evolution of a submarine canyon-channel system in a passive progradational margin. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT2 AbstractSpace-for-time substitution is a concept that has been widely applied, but not thoroughly tested in some fields of geomorphology. The objective of this study is to test whether the concept of space-for-time substitution is valid in reconstructing the evolution of a submarine canyonchannel system in a passive progradational margin. We use multibeam echosounder data and in situ measurements from the south Ebro Margin to analyse the morphology and morphometry of a sequence of submarine valleys ordered in terms of increasing valley thalweg length. The morphological model of submarine valley evolution that we can propose from this analysis is very similar to established models in the literature, which leads us to conclude that time can be substituted by space when reconstructing the evolution of submarine canyon and channel systems in the south Ebro Margin. By extracting morphometric information from the application of the space-for-time substitution model to our data, we identify a series of morphological patterns as a submarine canyon evolves in a passive progradational margin. These include the geometric similarity of canyon planform shape, an increase in canyon draining efficiency and in the influence of flank slope failures, and an evolution towards equilibrium between canyon form and imposed water and sediment load without net erosion or deposition taking place. We also observe that canyon elongation is higher downslope and that the canyon undergoes an early stage of rapid incision similar to the process of "erosion narrowing" reported in terrestrial rivers. We demonstrate that the conclusions of our study are not limited to submarine valleys in the south Ebro Margin but are applicable to other margins around the world. A C C E P T E D M A N U S C R I P TACCEPTED MANUSCRIPT 3 IntroductionGeoscientists are generally unable to fully observe landscape-forming processes because the time-scale of the observer and the time-scale of many geomorphic phenomena are very different.One approach to...

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Two fundamentally different types of submarine canyons along the continental margin of Equatorial Guinea

Cited by 163 publications

References 98 publications

Ecological Role of Submarine Canyons and Need for Canyon Conservation: A Review

Ecological Role of Submarine Canyons and Need for Canyon Conservation: A Review

Rapid Adjustment of Submarine Channel Architecture To Changes In Sediment Supply

Space-for-time substitution and the evolution of a submarine canyon–channel system in a passive progradational margin

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