Controls on turbidite sedimentation: Insights from a quantitative approach of submarine channel and lobe architecture (Late Quaternary Congo fan)

Type Article
Date 2016-04
Language English
Author(s) Picot M.1, Droz L.1, Marsset TaniaORCID2, Dennielou BernardORCID2, Bez M.3
Affiliation(s) 1 : Inst Univ Europeen Mer, Lab Domaines Ocean, UMR6538, Pl Nicolas Copernic, F-29280 Plouzane, France.
2 : IFREMER, UR GM, Lab Environm Sedimentaires, BP 70, F-29280 Plouzane, France.
3 : Total, Ctr Sci & Tech Jean Feger, Ave Larribau, F-64018 Pau, France.
Source Marine And Petroleum Geology (0264-8172) (Elsevier Sci Ltd), 2016-04 , Vol. 72 , P. 423-446
DOI 10.1016/j.marpetgeo.2016.02.004
WOS© Times Cited 80
Keyword(s) Turbidite system, Congo, Late Quaternary, Lobe complexes, Sedimentary cycles, Avulsion, Bathymetry, Seismic profiles
Abstract The role of internal and external forcing of sedimentation in turbidite systems remains a subject of debate. Here we propose new insights from the quantitative analysis of architectural parameters of the Congo Axial Fan.

Fifty-two channel-levee-lobe systems, spanning the last ca. 200 ka, are visible on the seafloor, most of them having slightly elongated lobe complexes at their termination. Volumes of lobe complexes (usually 3 to 196 km3) are highly variable in time and space. The cumulative volume of the lobe complexes represents approximately 30% of the volume of the Axial Fan.

The Axial Fan is sequentially divided into periods of increasing/decreasing channel lengths and basinward/landward migrations of avulsion points, representing successive prograding/retrograding architectural patterns called architectural cycles. These cycles are either symmetrical saw toothed and bell-shaped with progressive progradation and retrogradation phases, or asymmetrical, with long-lasting progradation phases and abrupt retrogradation phases that correspond to channel avulsions occurring high up on the fan.

Our study points to the interplay between internal and external factors controlling the architecture of the Congo Axial Fan. The local topographic constraint is a major factor in the fan’s stacking pattern. However, cyclic evolution of the architecture reveals major shifts in the deposition site that are linked to very upfan avulsion events. These events are interpreted to be driven by external factors (e.g. climate and/or eustatic sea-level change) that were able to drastically increase and/or coarsen the sediment supply to the fan.
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