Superposed deformation straddling the continental-oceanic transition in deep-water Angola

Cramez, Carlos; Jackson, Martin P. A.

doi:10.1016/s0264-8172(00)00053-2

Cited by 109 publications

(80 citation statements)

References 10 publications

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“…The maximum thickness of the Congo Tertiary deep-sea fan is estimated at about 5 km, based on the interpretation of regional seismic profiles (Anderson et al, 2000;Cramez and Jackson, 2000;Marton et al, 2000). Oligocene and Miocene turbidite systems have been particularly studied by the oil industry, due to the discovery of oil and gas reservoirs in the Tertiary series.…”

Section: 32 the Congo Deep-sea Fanmentioning

confidence: 99%

Geological overview of the Angola–Congo margin, the Congo deep-sea fan and its submarine valleys

Savoye

Babonneau

Dennielou

et al. 2009

Deep Sea Research Part II: Topical Studies in Oceanography

132

155

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The Congo deep-sea fan is one of the largest fans in the world still affected by presently active turbidity currents. The present activity of deep-sea sedimentary processes is linked to the existence of a direct connection between the Congo River estuary and the Congo canyon head that allows relatively continuous sediment feeding of the deep-sea environment, in spite of a wide continental shelf (150 km). Because of this important activity in terms of sedimentary processes, the deep-sea environment of the Congo-Angola margin presents major interests concerning physical, chemical and biological studies near the sea floor. The main aim of this paper is to present the initial geological context of the BioZaire Program, showing a synthesis of the major results of the ZaïAngo Project including (1) the brief geological setting of the Congo-Angola margin, (2) the structure of the modern Congo deep-sea fan, (3) the sedimentary architecture of the recent Congo turbidite system (from the canyon to the distal lobes), and (4) the recent and present turbidite sedimentation. In order to provide useful information and advice relevant to biological and geochemical studies across the Congo sedimentary system, this article focuses on the present sedimentary processes and the present activity of turbidity current along the Congo canyon and channel.Keywords : Congo-Angola margin, Congo channel, sedimentary deposits, turbidite .1 IntroductionThe accumulation of marine sediment seaward of the Congo River estuary is probably one of the greatest in the world for a submarine system that is still active today. In the continental domain, the Congo sedimentary system is composed by a wide drainage basin, the river and its tributaries. In the nearshore and marine domain: it consists of the estuary, the canyon, which acts mainly as a by-pass zone, and finally an area of preferential sedimentation at the foot of the continental slope and in the deep basin. The Congo submarine system has been geologically studied since Buchanan in 1887 (submarine cable survey) and was the focus of the ZaïAngo project team from 1998 to 2005. Several types of evidence of Holocene and very recent activity in the canyon have been described and linked to sedimentary processes such as turbidity currents, river floods, slides, gas hydrate formation and fluid escape. The aim of this paper is to synthesize the geological knowledge of the area and in particular the results of the ZaïAngo project in order to provide useful information and advice relevant to biological and geochemical studies across the Congo sedimentary system. Marine biologists and oceanographers are usually not familiar with turbidite deposits. These sedimentary deposits were first recognised and described in outcrops of ancient sedimentary series (Bouma, 1962;Walker, 1978;Mutti, 1992). They are generated by submarine gravity processes and they build large sedimentary systems in deep-water environments, termed deep-sea fans. Deep-sea fans are well developed from the foot of the continental slope...

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Section: 32 the Congo Deep-sea Fanmentioning

confidence: 99%

Geological overview of the Angola–Congo margin, the Congo deep-sea fan and its submarine valleys

Savoye

Babonneau

Dennielou

et al. 2009

Deep Sea Research Part II: Topical Studies in Oceanography

132

155

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“…Cramez & Jackson 2000;Mohriak et al 1998Mohriak et al , 2002. Lacking a basinward regional dip, a sedimentary succession above a mechanically weak layer can still be induced to extend by asymmetric loading, such as from a prograding shelf.…”

Section: Gravity Loading Spreading and Slidingmentioning

confidence: 99%

Potential mechanisms for the genesis of Cenozoic domal structures on the NE Atlantic margin: pros, cons and some new ideas

Doré¹,

Lundin

Kusznir

et al. 2008

100

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“…Early growth structures within the Albian carbonate witness the onset of extensional deformation, that is sealed by Senonian deposits on the shelf Marton et al, 2000;Valle et al, 2001), while extension continues until Campanian on the upper slope (Spathopoulos, 1996;Cramez and Jackson, 2000). A second major phase of extension occurred on the slope during the Oligocene: reactivation of faults resulted in the formation of the rafts (Duval et al, 1992;Cramez and Jackson, 2000;Marton et al, 2000;Valle et al, 2001). A further reactivation occurred in the late Miocene and Pliocene (Spathopoulos, 1996;Nzé Abeigne, 1997;Marton et al, 2000).…”

Section: Gravitational Tectonicsmentioning

confidence: 99%

South Atlantic continental margins of Africa: A comparison of the tectonic vs climate interplay on the evolution of equatorial west Africa and SW Africa margins

Séranne¹,

Anka²

2005

Journal of African Earth Sciences

135

106

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Africa displays a variety of continental margin structures, tectonic styles and sedimentary records. The comparative review of two representative segments: the equatorial western Africa and the SW Africa margins, helps in analysing the main controlling factors on the development of these margins. Early Cretaceous active rifting south of the Walvis Ridge resulted in the formation of the SW Africa volcanic margin that displays thick and wide intermediate igneous crust, adjacent to a thick unstretched continental crust. The non-volcanic mode of rifting north of the Walvis ridge, led to the formation of the equatorial western Africa margin, characterised by a wide zone of crustal stretching and thinning, and thick, extensive, synrift basins. Contrasting lithologies of the early post-rift (salt vs shale) determined the style of gravitational deformation, whilst periods of activity of the decollements were controlled by sedimentation rates. Regressive erosion across the prominent shoulder uplift of SW Africa accounts for high clastic sedimentation rate during Late Cretaceous to Eocene, while dominant carbonate production on equatorial western Africa shelf suggests very little erosion of a low hinterland. The early Oligocene long-term climate change had contrasted response in both margins. Emplacement of the voluminous terrigenous Congo deep-sea fan reflects increased erosion in equatorial Africa, under the influence of wet climate, whereas establishment of an arid climate over SW Africa induced a drastic decrease of denudation rate, and thus reduced sedimentation on the margin. Neogene emplacement of the African superswell beneath southern Africa was responsible for renewed onshore uplift on both margins, but it accelerated erosion only in the Congo catchment, due to wetter climatic conditions. Neogene high sedimentation rate reactivated gravitational tectonics that had remained quiescent since late Cretaceous.

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Superposed deformation straddling the continental-oceanic transition in deep-water Angola

Cited by 109 publications

References 10 publications

Geological overview of the Angola–Congo margin, the Congo deep-sea fan and its submarine valleys

Geological overview of the Angola–Congo margin, the Congo deep-sea fan and its submarine valleys

Potential mechanisms for the genesis of Cenozoic domal structures on the NE Atlantic margin: pros, cons and some new ideas

South Atlantic continental margins of Africa: A comparison of the tectonic vs climate interplay on the evolution of equatorial west Africa and SW Africa margins

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