Transport of terrestrial organic matter in the Ogooué deep sea turbidite system (Gabon)

Biscara, Laurie; Mulder, Thierry; Martinez, Philippe; Baudin, François; Etcheber, Henri; Jouanneau, J. M.; Garlan, Thierry

doi:10.1016/j.marpetgeo.2010.12.002

Cited by 57 publications

(25 citation statements)

References 53 publications

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“…Turbiditic deposits (characterized by sharp variations in grain size) could also explain the variability in the quality and quantity of OM in cores, as shown in the Ogooué deep-sea turbiditic system (Biscara et al, 2011). However, in the active Congo deep-sea fan area, it is unlikely that the OM distribution in sediments would be controlled by grain Fig.…”

Section: Organic Matter Deposition and Distribution In Lobe Sedimentsmentioning

confidence: 99%

“…The marine limit for δ 13 C is also shown (gray bar on right). The marine OM δ 13 C org end-member was selected based on the range of data reported from the Gulf of Guinea (Fischer et al, 1998;Baudin et al, 2010;Biscara et al, 2011). size, considering that all sediments cored are already very fine, indicating particle segregation is more important upstream than on the distal lobe.…”

Section: Organic Matter Deposition and Distribution In Lobe Sedimentsmentioning

confidence: 99%

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Organic matter characterization and distribution in sediments of the terminal lobes of the Congo deep-sea fan: Evidence for the direct influence of the Congo River

et al. 2015

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International audienceThe terminal lobe complex of the Congo River submarine fan sits on the abyssal Atlantic plain, at 5000 m water depth, 760 km offshore from the river mouth estuarine area. While most rivers deliver particulate material to the continental shelf, particulate matter from the Congo River largely bypasses the shelf and is transported by turbidity currents through the Congo submarine canyon system. We determined the quantity and quality of the organic matter reaching the terminal lobe complex at five sites with marked morphological differences that may influence the distribution of organic matter. A suite of bulk geochemical (% OC, δ13Corg, δ15N, C: N), 137Cs and palynofacies analyses were done on cores collected from the terminal lobe area. These results were also compared to the composition of sediments collected upstream at the Malebo Pool (Congo River).Distal lobe complex sediments contain high amounts of terrestrial organic carbon (3–5 wt.%) that is homogeneously distributed in surficial (22 cm) and deeper sediments (580 cm) silty–clay facies. Strongly altered soil-derived organic matter with well-preserved land plant detritus from the Congo River predominates. A terrestrial soil origin for the particulate load was confirmed by the elevated 137Cs activity in lobe sediments. The vertical distribution of the 137Cs signal suggests that there has been a massive arrival of terrestrial sediments since 1963, consistent with a turbiditic origin. From the locations surveyed, we estimate a maximum accumulation of terrestrial organic carbon of ca. 1 kg OC m− 2 y− 1 for the distal lobe. However, transport modifies the organic matter both in terms of quantity and quality. Observed differences were attributed to preferential degradation of nitrogenous matter during diagenesis and to the addition of highly remineralized marine organic matter.Results from our temporal reference site (E) suggest that organic matter may be preserved in turbidite facies for thousands of years. The good preservation state of the accumulated organic matter shows that turbiditic lobe complexes should be considered as a sink for terrestrial organic carbon in the deep ocean

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Section: Organic Matter Deposition and Distribution In Lobe Sedimentsmentioning

confidence: 99%

Section: Organic Matter Deposition and Distribution In Lobe Sedimentsmentioning

confidence: 99%

Organic matter characterization and distribution in sediments of the terminal lobes of the Congo deep-sea fan: Evidence for the direct influence of the Congo River

et al. 2015

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“…It has been increasingly applied to the characterization of organic matter (OM) in soils (Di Giovanni et al, 2000;Disnar et al, 2003;Hetényi et al, 2005;Sebag et al, 2006;Graz et al, 2012;Saenger et al, 2013;Hétényi and Nyilas, 2014), the detection of black carbon (Copard et al, 2006;Poot et al, 2009) and even the analysis of pure organic products (Carrie et al, 2012). It has also been applied for several decades to the study of recent lacustrine sediments (Campy et al, 1994;Di Giovanni et al, 1998;Meyers and Lallier-Vergès, 1999;Ariztegui et al, 2001;Steinmann et al, 2003;Sanei et al, 2005;Jacob et al, 2004;Boussafir et al, 2012;Zocatelli et al, 2012;Lavrieux et al, 2013;Sebag et al, 2013, amongst others) or recent marine sediments (Peters and Simoneit, 1982;Hussain and Warren, 1991;Calvert et al, 1992;Combourieu et al, 1999;Ganeshram et al, 1999;Ozcelik and Altunsoy, 2000;Holtvoeth et al, 2001Holtvoeth et al, , 2003Holtvoeth et al, , 2005Tamburini et al, 2003;Baudin et al, 2007Baudin et al, , 2010Kim et al, 2007;Marchand et al, 2008;Tribovillard et al, 2008Tribovillard et al, , 2009Biscara et al, 2011;…”

Section: Introductionmentioning

confidence: 99%

Guidelines for Rock–Eval analysis of recent marine sediments

Baudin

Disnar

Aboussou

et al. 2015

Organic Geochemistry

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“…Turbidite emplacement is by nature discontinuous and generates layers of sediment in which organic matter quantity, type and state of preservation are usually heterogeneous (Biscara et al, 2011;Caja and Permanyer, 2008;McArthur et al, 2016aMcArthur et al, , 2016bMeyers et al, 1996;Saller et al, 2006;Watanabe and Akiyama, 1998). This is not the case in the Congo mud-rich turbidite system, in which the organic matter distribution appears very homogeneous.…”

Section: Processes Responsible For Homogeneous Distribution Of Organimentioning

confidence: 99%

Origin and distribution of the organic matter in the distal lobe of the Congo deep-sea fan – A Rock-Eval survey

Baudin

Stetten

Schnyder

et al. 2017

Deep Sea Research Part II: Topical Studies in Oceanography

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International audienceThe Congo River, the second largest river in the world, is a major source of organic matter for the deep Atlantic Ocean because of the connection of its estuary to the deep offshore area by a submarine canyon which feeds a vast deep-sea fan. The lobe zone of this deep-sea fan is the final receptacle of the sedimentary inputs presently channelled by the canyon and covers an area of ~2500 km². The quantity and the source of organic matter preserved in recent turbiditic sediments from the distal lobe of the Congo deep-sea fan were assessed using Rock-Eval pyrolysis analyses. Six sites, located at approximately 5000 m water-depth, were investigated. The mud-rich sediments of the distal lobe contain high amounts of organic matter (~3.5 to 4% Corg), the origin of which is a mixture of terrestrial higher-plant debris, soil organic matter and deeply oxidized phytoplanktonic material. Although the respective contribution of terrestrial and marine sources of organic matter cannot be precisely quantified using Rock-Eval analyses, the terrestrial fraction is dominant according to similar hydrogen and oxygen indices of both suspended and bedload sediments from the Congo River and that deposited in the lobe complex. The Rock-Eval signature supports the 70% to 80% of the terrestrial fraction previously estimated using C/N and δ13Corg data. In the background sediment, the organic matter distribution is homogeneous at different scales, from a single turbiditic event to the entire lobe, and changes in accumulation rates only have a limited effect on the quantity and quality of the preserved organic matter. Peculiar areas with chemosynthetic bivalves and/or bacterial mats, explored using ROV Victor 6000, show a Rock-Eval signature more or less similar to background sediment. This high organic carbon content associated to high sedimentation rates (> 2 to 20 mm.yr−1) in the Congo distal lobe complex implies a high burial rate for organic carbon. Consequently, the Congo deep-sea fan represents an enormous sink of terrestrial organic matter when compared to other turbiditic systems over the world

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Transport of terrestrial organic matter in the Ogooué deep sea turbidite system (Gabon)

Cited by 57 publications

References 53 publications

Organic matter characterization and distribution in sediments of the terminal lobes of the Congo deep-sea fan: Evidence for the direct influence of the Congo River

Organic matter characterization and distribution in sediments of the terminal lobes of the Congo deep-sea fan: Evidence for the direct influence of the Congo River

Guidelines for Rock–Eval analysis of recent marine sediments

Origin and distribution of the organic matter in the distal lobe of the Congo deep-sea fan – A Rock-Eval survey

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