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Registros recuperados: 8
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Aliphatic hydrocarbons and triterpenes of the Congo deep sea fan 5
Mejanelle, Laurence; Riviere, Beatrice; Pinturier, Laurence; Khripounoff, Alexis; Baudin, Francois; Dachs, Jordi.
Hydrocarbons were analyzed in sediments from the Congo River deep-sea fan, from the Congo River, and in sinking particles collected by sediment traps 40 m above the sediment. Studied sites encompassed three lobes of decreasing age of formation along the canyon: sites A, F and C and a another lobe system, disconnected from the active channel since 4 ka, Site E. Terrestrial long-chain odd n-alkanes were dominant in all sediments of the lobe system. Unsaturated terpenoids sourced by higher plants, such as gammacerene, lupene, ursene and oleanene, were also detected. At site C, characterized by high accumulation rates (10–20 cm yr−1), the organic matter spends less time in the oxic layer than at other sites and high phytadiene concentrations (10 to 17 μg...
Tipo: Text Palavras-chave: Congo fan; Hydrocarbons; NAH; Hopanes; Hopenes; Sediments; Turbidite system.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00388/49902/50472.pdf
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Comparison of 240 ka long organic carbon and carbonate records along a depth transect in the Timor Sea: Primary signals versus preservation changes 5
Liu, Wei; Baudin, Francois; Moreno, Eva; Dewilde, Fabien; Caillon, Nicolas; Fang, Nianqiao; Bassinot, Franck.
Total organic carbon (TOC) and calcium carbonate (CaCO3) records from different water depths in the Timor Sea (NE Indian Ocean) are compared in order to better reconstruct past changes in pelagic productivity, highlight the impact of preservation at depth, and unravel the interplay of organic carbon and carbonate sedimentation. New data are presented for core MD01-2376 located at 2376 m depth. These results are compared, over the last 240 ka, with published data on two neighboring cores (MD01-2378, 1783 m and MD98-2166, 3875 m). TOC fluctuations show strong glacial/interglacial variations and Milankovitch-type oscillations (i.e., dominant frequencies centered on the 100, 41, and 23 ka bands), with an enrichment during cold periods that reflects an increase...
Tipo: Text
Ano: 2014 URL: https://archimer.ifremer.fr/doc/00290/40149/39258.pdf
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Distribution of the organic matter in the channel-levees systems of the Congo mud-rich deep-sea fan (West Africa). Implication for deep offshore petroleum source rocks and global carbon cycle 5
Baudin, Francois; Disnar, Jean-robert; Martinez, Philippe; Dennielou, Bernard.
The quantity and the source of organic matter preserved in the Recent turbiditic channel-levees systems around 4000 m-depth off the Congo River were determined using bulk geochemical approaches (Rock-Eval, elemental and isotopic analyses) as well as molecular and optical analyses on selected samples. These mud-rich sediments contain high amount of organic matter (3% Corg on average), the origin of which is a mixture of terrestrial higher-plant debris and deeply oxidized phytoplanktonic material. Although the relative contribution of continental source versus marine source of the organic matter cannot be precisely quantified, the continental fraction appears significant (at least 70-80%) especially for such depths and distances from the coast. The organic...
Tipo: Text Palavras-chave: South-East Atlantic; Turbidites; Carbon isotopes; Nitrogen isotopes; Biomarkers; Source rocks.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00006/11700/9285.pdf
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Evidence and age estimation of mass wasting at the distal lobe of the Congo deep-sea fan 5
Croguennec, Claire; Ruffine, Livio; Dennielou, Bernard; Baudin, Francois; Caprais, Jean-claude; Guyader, Vivien; Bayon, Germain; Brandily, Christophe; Le Bruchec, Julie; Bollinger, Claire; Germain, Yoan; Droz, Laurence; Babonneau, Nathalie; Rabouille, Christophe.
On continental margins, sulfate reduction occurs within the sedimentary column. It is coupled with the degradation of organic matter and the anaerobic oxidation of methane. These processes may be significantly disturbed by sedimentary events, leading to transient state profiles for the involved chemical species. Yet, little is known about the impact of turbidity currents and mass wasting on the migration of chemical species and the redox reactions in which they are involved. Due to its connection to the River, the Congo deep-sea fan continuously receives huge amount of organic matter-rich sediments primarily transported by turbidity currents, which impact on the development of the associated ecosystems (Rabouille et al., 2016). Thus, it is well suited to...
Tipo: Text
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00363/47410/47403.pdf
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High-resolution vegetation history of West Africa during the last 145 ka 5
Dalibard, Mathieu; Popescu, Speranta-maria; Maley, Jean; Baudin, Francois; Melinte-dobrinescu, Mihaela-carmen; Pittet, Bernard; Marsset, Tania; Dennielou, Bernard; Droz, Laurence; Suc, Jean-pierre.
The essential characteristics of the vegetation dynamics of tropical Africa remain only partially known. This study assesses the succession of vegetation-types over Central Africa during the last two glacial/interglacial cycles. Analysis of core KZai 02, which contains pollen from the Zaire River watershed (latitudes 9°N-13°S), allows the investigation of long-term patterns of plant ecosystem development and their climatic causes. Core KZai 02 (18.20 m long) was recovered from 6°24.20′S/9°54.10′E in the uppermost axial edifice of the Zaire deep sea fan. The chronology of this sedimentary archive was established using nannofossils and correlations of pollen and total organic carbon signals with the nearby core GeoB1008. The pollen record indicates that: (i)...
Tipo: Text Palavras-chave: Central Africa; Climate; Environmental parameters; Late Pleistocene; Pollen; Vegetation dynamics.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00199/31031/29436.pdf
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Influence of orbital forcing and sea level changes on sedimentation patterns in the Timor Sea during the last 260 ka 5
Moreno, Eva; Bassinot, Franck; Baudin, Francois; Venec-peyre, Marie-therese.
[1] A multiproxy study of core MD98-2166 makes it possible to investigate the influence of orbital forcing and sea level changes on Timor Sea sedimentation during the last 260 ka. Spectral analysis reveals a strong imprint of obliquity in all proxies. This is particularly puzzling for the CaCO(3) and total organic carbon (TOC) records since recent data obtained on nearby core MD01-2378, collected at a shallower water depth, showed a concentration of spectral power in the eccentricity and precession bands. Our results suggest that while sedimentary record in shallower core MD01-2378 shows a clear low-latitude response, that of core MD98-2166 reflects a stronger influence of high-latitude forcing through deepwater changes. In addition, Rock-Eval analyses...
Tipo: Text
Ano: 2008 URL: https://archimer.ifremer.fr/doc/00238/34885/33152.pdf
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Organic carbon accumulation in modern sediments of the Angola basin influenced by the Congo deep sea fan 5
Baudin, Francois; Martinez, Philippe; Dennielou, Bernard; Charlier, Karine; Marsset, Tania; Droz, Laurence; Rabouille, Christophe.
Geochemical data (total organic carbon-TOC content, δ13Corg, C:N, Rock-Eval analyses) were obtained on 150 core tops from the Angola basin, with a special focus on the Congo deep sea fan. Combined with the previously published data, the resulting dataset (322 stations) shows a good spatial and bathymetric representativeness. TOC content and δ13Corg maps of the Angola basin were generated using this enhanced dataset. The main difference in our map with previously published ones is the high terrestrial organic matter content observed downslope along the active turbidite channel of the Congo deep sea fan till the distal lobe complex near 5,000 m of water-depth. Interpretation of downslope trends in TOC content and organic matter composition indicates that...
Tipo: Text Palavras-chave: Organic matter; Recent sediments; South Atlantic Ocean; Turbidites.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00369/47974/47999.pdf
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Origin and distribution of the organic matter in the distal lobe of the Congo deep-sea fan – A Rock-Eval survey 5
Baudin, Francois; Stetten, Elsa; Schnyder, Johann; Charlier, Karine; Martinez, Philippe; Dennielou, Bernard; Droz, Laurence.
The 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...
Tipo: Text Palavras-chave: Recent sediments; Congo turbidite system; Organic matter; Rock-Eval pyrolysis.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00369/48018/48095.pdf
Registros recuperados: 8
Primeira ... 1 ... Última
 

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