The Congolobe project, a multidisciplinary study of Congo deep-sea fan lobe complex: Overview of methods, strategies, observations and sampling

Abstract

International audienceThe presently active region of the Congo deep-sea fan (around 330 000 km2), called the terminal lobes or lobe complex, covers an area of 2500 km2 at 4700–5100 m water depth and 750–800 km offshore. It is a unique sedimentary area in the world ocean fed by a submarine canyon and a channel-levee system which presently deliver large amounts of organic carbon originating from the Congo River by turbidity currents. This particularity is due to the deep incision of the shelf by the Congo canyon, up to 30 km into the estuary, which funnels the Congo River sediments into the deep-sea. The connection between the river and the canyon is unique for major world rivers

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

“…Such flows could therefore be highly capable of transporting microplastics, being of similar densities to organic material, to the distal parts of the fan. This organic material, together with relatively oxygenated water, is important for benthic ecosystems at extremely deep water depths (Rabouille et al, 2017). Similar distributions of organic material are recorded in ancient submarine fan systems (e.g., Stanley, 1982;McArthur et al, 2017).…”

Morphology, structure, composition and build-up processes of the active channel-mouth lobe complex of the Congo deep-sea fan with inputs from remotely operated underwater vehicle (ROV) multibeam and video surveys

“…It is still presently active and receives sediments as evidenced by a current speed peak of 8.4 cm.s --1 and high input of sediment (Vangriesheim et al, 2009a) recorded on the 4 th February 2004 by current meters and sediment traps deployed 60 m above the sea floor on the lobe area. High sediment accumulation (~0.5 to 20 cm.y --1 , calculated by 210 Pb exc and 137 Cs analysis (Rabouille et al, 2009;Rabouille et al, this issue) indicates that the lobe complex has considerably grown over the last century. Based on AMS radiocarbon dating, Savoye et al (2009) have suggested that the onset of the lobe complex was between 6.7 and 5.1 ka BP.…”

“…earthquake) that can affect both the shear stress and sediment shear strength. The Congo lobe complex convenes several characteristics that may actually promote mass wasting, (1) the area records very--high accumulation rates (0.4 to 22 cm.yr --1 ,(Rabouille et al, 2009;Rabouille et al, this issue) that are in the order of those measured on shallow water muddy subaqueous delta(Cattaneo et al, 2003;Kuehl et al, 1997;Kuehl et al, 1982;Liu et al, 2004;Miralles et al, 2005). This rapid accumulation may lead to excess pore pressure, underconsolidation and low shear strength.…”

Energy transfer in the Congo deep-sea fan: From terrestrially-derived organic matter to chemosynthetic food webs

“…Moreover, the observation of faunal aggregations and microbial mats similar to those colonising cold-seeps (Rabouille et al, this volume; Sen et al, submitted, this volume) raised the question of the origin of the reduced compounds (hydrogen sulphide) required for their development and the link with the turbidites. We particularly focused the sampling in habitats created by vesicomyid bivalves, resembling those colonising cold-seeps on pockmarks of the same region (Olu et al, 2009;Olu-Le Roy et al, 2007), with high densities and shared species (Decker et al, in press, this volume;Rabouille et al, this volume;Teixeira et al, 2013).…”