The long-term evolution of the Congo deep-sea fan: A basin-wide view of the interaction between a giant submarine fan and a mature passive margin (ZaiAngo project)
Type | Article | ||||||||
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Date | 2009-05 | ||||||||
Language | English | ||||||||
Author(s) | Anka Zahie1, 2, Seranne Michel2, Lopez Michel2, Scheck-Wenderoth Magdalena1, Savoye Bruno3 | ||||||||
Affiliation(s) | 1 : Geoforschungszentrum Potsdam, Sect 4 3, D-14473 Potsdam, Germany. 2 : Univ Montpellier 2, Case 060, Geosci Montpellier Umr 5243, F-34095 Montpellier 05, France. 3 : IFREMER, F-29280 Plouzane, France. |
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Source | Tectonophysics (0040-1951) (Elsevier), 2009-05 , Vol. 470 , N. 1-2 , P. 42-56 | ||||||||
DOI | 10.1016/j.tecto.2008.04.009 | ||||||||
WOS© Times Cited | 59 | ||||||||
Keyword(s) | Submarine fan, Lower Congo basin, Submarine canyon, Salt tectonics, Angola escarpment, West Africa Margin | ||||||||
Abstract | We have integrated the relatively unknown distal domains of the Lower Congo basin, where the main depocenters of the Congo submarine fan are located, with the better-constrained successions on the shelf and upper slope, through the analysis of thousands of km of 2D seismic reflection profiles off-shore the Congo-Angola passive margin. The basin architecture is depicted by two ca. 800-km-long regional cross sections through the northern (Congo) and southern (Angola) margin. A large unit deposited basinward of the Aptian salt limit is likely to be the abyssal-plain equivalent of the upper-Cretaceous carbonate shelf that characterized the first post-rift deposits in West-equatorial African margins. A latest-Turonian shelf-deepening event is recorded in the abyssal plain as a long period (Coniacian-Eocene) of condensed sedimentation and basin starvation. The onset of the giant Tertiary Congo deep-sea fan in early Oligocene following this event reactivates the abyssal plain as the main depocenter of the basin. The time-space partitioning of sedimentation within the deep-sea fan results from the interplay among increasing sediment supply, margin uplift, rise of the Angola salt ridge, and canyon incision throughout the Neogene. Oligocene-early Miocene turbidite sedimentation occurs mainly in NW-SE grabens and ponded inter-diapir basins on the southern margin (Angola). Seaward tilting of the margin and downslope salt withdrawal activates the up-building of the Angola escarpment, which leads to a northward (Congo) shift of the transfer zones during late Miocene. Around the Miocene-Pliocene boundary, the incision of the Congo submarine canyon confines the turbidite flows and drives a general basinward progradation of the submarine fan into the abyssal plain The slope deposition is dominated by fine-grained hemipelagic deposits ever since. Results from this work contribute to better understand the signature in the ultra-deep deposits of processes acting on the continental margin as well as the basin-wide sediment redistribution in areas of high river input. (C) 2008 Elsevier B.V. All rights reserved. | ||||||||
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