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Authigenic carbonate mounds from active methane seeps on the southern Aquitaine Shelf (Bay of Biscay, France): evidence for anaerobic oxidation of biogenic methane and submarine groundwater discharge during formation ArchiMer
Pierre, Catherine; Demange, Jerome; Blanc-valleron, Marie-madeleine; Dupre, Stephanie.
The widespread methane emissions that were discovered in 2013 on the Aquitaine Shelf at water depth between 140 and 220 m are associated with authigenic carbonate crusts that cover meter-high subcircular reliefs of 10 to 100 m in diameter. These authigenic carbonates are primarily aragonite plus calcite and dolomite, which cement the fine- to medium-grained sandy sediment. The carbonate cement is often pierced by numerous circular cavities of 5 to 10 µm in diameter that are considered to be moulds of gas bubbles. Conversely, micron-sized cavities in the aragonite crystals are attributed to dissolution features, in relation to the production of CO2 during the aerobic oxidation of methane. The oxygen isotopic compositions of bulk carbonate (+1.7 to +3.7‰)...
Tipo: Text Palavras-chave: Aquitaine Shelf; Methane-derived authigenic carbonates; Oxygen isotopes; Carbon isotopes; Submarine groundwater discharge; Anaerobic oxidation of methane; Aerobic oxidation of methane.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00361/47209/47164.pdf
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Authigenic carbonates from methane seeps of the Congo deep-sea fan ArchiMer
Pierre, Catherine; Fouquet, Yves.
Submersible investigations with the ROV Victor 6000 of some pockmark structures on the seafloor of the Congo deep-sea fan have shown that they are active venting sites of methane-rich fluids, associated with abundant fauna and carbonate crusts. Moreover, methane hydrates have been observed both outcropping and deep in the sediments in the centre of the "Regab" giant pockmark. Authigenic carbonates, mostly calcite sometimes mixed with aragonite, are cementing the sedimentary matrix components and fauna; diatoms are abundant but only as moulds, indicating that biogenic silica dissolution occurred in situ synchronous with carbonate precipitation. The occurrence of diagenetic barite and pyrite in some carbonate crusts demonstrates that they can be formed...
Tipo: Text Palavras-chave: Oxygen isotopes; Carbon isotopes; Congo deep sea fan; Gas hydrate; Methane seep; Authigenic carbonate.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2608.pdf
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Carbon and Nitrogen Acquisition in Shallow and Deep Holobionts of the Scleractinian Coral S. pistillata ArchiMer
Ezzat, Leila; Fine, Maoz; Maguer, Jean-francois; Grover, Renaud; Ferrier-pages, Christine.
Reef building corals can host different symbiont genotypes (clades), and form distinct holobionts in response to environmental changes. Studies on the functional significance of genetically different symbionts have focused on the thermal tolerance rather than on the nutritional significance. Here, we characterized the nitrogen and carbon assimilation rates, the allocation patterns of these nutrients within the symbiosis, and the trophic condition of two distinct holobionts of Stylophora pistillata: one associated with Symbiodinium Glade A in shallow reefs and the other one associated with Glade C in mesophotic reefs. The main findings are that: (1) Glade C-symbionts have a competitive advantage for the acquisition of carbon at low irradiance compared to...
Tipo: Text Palavras-chave: Light acclimation; Carbon isotopes; Nitrogen isotopes; Clades; Nitrate; Ammonium; Scleractinian coral; Mesophotic coral.
Ano: 2017 URL: https://archimer.ifremer.fr/doc/00602/71414/69897.pdf
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Carbon isotope fluctuations in Precambrian carbonate sequences of several localities in Brazil Anais da ABC (AABC)
SIAL,ALCIDES N.; FERREIRA,VALDEREZ P.; DEALMEIDA,AFONSO R.; ROMANO,ANTONIO W.; PARENTE,CLOVIS V.; DACOSTA,MARCONDES L.; SANTOS,VICTOR H..
Carbon isotope fluctuations in Precambrian sedimentary carbonates between 2.8 Ga and 0.60 Ga in Brazil are examined in this study. The carbonate facies of the BIF of the 2.8 Ga-old Carajás Formation, state of Pará in northern Brazil, has rather homogeneous delta13C (-5 o/ooPDB), compatible with carbonatization of a silicate protolith by a CO2-rich fluid from mantle degassing. The Paleoproterozoic Gandarela Formation, state of Minas Gerais, displays a narrow delta13C variation (-1.5 to +0.5 o/oo) compatible with carbon isotope signatures of carbonates deposited around 2.4 Ga worldwide. The Fecho do Funil Formation has probably recorded the Lomagundi delta13C positive anomaly (+6.4 to +7.1 o/ooPDB). The magnesite-bearing carbonates of the Orós mobile belt,...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Carbon isotopes; Carbonates; Chemostratigraphy; Archean; Paleoproterozoic; Neoproterozoic.
Ano: 2000 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652000000400006
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CHARACTERIZATION OF HEADWATERS PEATS OF THE RIO ARAÇUAÍ, MINAS GERAIS STATE, BRAZIL Rev. Bras. Ciênc. Solo
Bispo,Diêgo Faustolo Alves; Silva,Alexandre Christofaro; Christofaro,Cristiano; Silva,Max Leandro Naves; Barbosa,Maurício Soares; Silva,Bárbara Pereira Christofaro; Barral,Uidemar Moraes.
Peatlands are soil environments that accumulate water and organic carbon and function as records of paleo-environmental changes. The variability in the composition of organic matter is reflected in their morphological, physical, and chemical properties. The aim of this study was to characterize these properties in peatlands from the headwaters of the Rio Araçuaí (Araçuaí River) in different stages of preservation. Two cores from peatlands with different vegetation types (moist grassland and semideciduous seasonal forest) from the Rio Preto [Preto River] headwaters (conservation area) and the Córrego Cachoeira dos Borges [Cachoeira dos Borges stream] (disturbed area) were sampled. Both are tributaries of the Rio Araçuaí. Samples were taken from layers of 15...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Histosol; Soil organic matter; Carbon isotopes.
Ano: 2015 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832015000200475
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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 ArchiMer
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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Experimental shift in diet Delta13C: A potential tool for ecophysiological studies in marine bivalves ArchiMer
Paulet, Yves-marie; Lorrain, Anne; Richard, Joëlle; Pouvreau, Stephane.
To test the potential of diet switching experiments in ecophysiological studies of marine invertebrates, stable carbon isotope ratios were measured at different seasons in the gonad, adductor muscle, digestive gland and gills of scallops (Pecten maximus) and oysters (Crassostrea gigas) held for 15 days on a constant diet of phytoplankton depleted in 13C. The aim of this study was to determine if differences in carbon incorporation could be detected among species, seasons and organs, and if so, whether it was consistent with their known energy-allocation patterns. After offering the new diet, isotope values of the different organs gradually shifted and significant differences among organs, seasons and species were found. A carbon incorporation index (CII)...
Tipo: Text Palavras-chave: Crassostrea gigas; Pecten maximus; Carbon isotopes; Metabolism; Energy allocation.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-1202.pdf
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Interdisciplinary paleovegetation study in the Fernando de Noronha Island (Pernambuco State), northeastern Brazil Anais da ABC (AABC)
Pessenda,Luiz C.R.; Gouveia,Susy E.M.; Ledru,Marie-Pierre; Aravena,Ramon; Ricardi-Branco,Fresia S.; Bendassolli,José A.; Ribeiro,Adauto de S.; Saia,Soraya E.M.G.; Sifeddine,Abdelfettah; Menor,Eldemar de A.; Oliveira,Sônia M.B. de; Cordeiro,Renato C.; Freitas,Ângela M. de M.; Boulet,René; Filizola,Heloisa F..
The aim of this research was to reconstruct vegetation changes (with climate inferences) that occurred during the Holocene in the Fernando de Noronha Island, Pernambuco State, northeastern Brazil. The research approach included the use of geochemical (mineralogy, elemental), carbon isotopes (δ13C, 14C) and pollen analyses in soil organic matter (SOM) and sediments collected in Lagoa da Viração and Manguezal do Sueste. The carbon isotopes data of SOM indicated that there was no significant vegetation changes during the last 7400 BP, suggesting that the climate was not the determinant factor for the vegetation dynamics. The pollen analysis of the sediment of a core collected in the Lagoa da Viração showed the absence of Quaternary material in the period...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Pollen; Carbon isotopes; Paleovegetation; Fernando de Noronha; Holocene.
Ano: 2008 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652008000400009
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The Late Holocene upper montane cloud forest and high altitude grassland mosaic in the Serra da Igreja, Southern Brazil Anais da ABC (AABC)
SCHEER,MAURICIO B.; CURCIO,GUSTAVO R.; RODERJAN,CARLOS V..
Many soils of the highlands of Serra do Mar, as in other mountain ranges, have thick histic horizons that preserve high amounts of carbon. However, the age and constitution of the organic matter of these soils remain doubtful, with possible late Pleistocene or Holocene ages. This study was conducted in three profiles (two in grassland and one in forest) in Serra da Igreja highlands in the state of Paraná. We performed δ13C isotope analysis of organic matter in soil horizons to detect whether C3 or C4 plants dominated the past communities and 14C dating of the humin fraction to obtain the age of the studied horizons. C3 plants seem to have dominated the mountain ridges of Serra da Igreja since at least 3,000 years BP. Even though the Serra da Igreja may...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Atlantic Rain Forest; Carbon isotopes; Humin fraction; Radiocarbon dating; Sea Mountain Range; Upper montane vegetation.
Ano: 2013 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652013000200769
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Tramas tróficas en sistemas frontales del Mar Argentino: estructura, dinámica y complejidad analizada mediante isótopos estables OceanDocs
Gaitán, E.N..
Two of the most important frontal systems of the Argentine Sea (SW Atlantic Ocean) were compared to obtain evidences on the regulatory mechanisms of food web length, incorporating both spatial (areas within fronts) and temporal (presence or absence of frontal structure) variability. The stable isotopes of Carbon and Nitrogen were used to evaluate the origin and composition of the organic matter used by primary consumers, the structure of food webs, the trophic levels of several taxa and the benthic-pelagic coupling within each system. In the Río de la Plata estuarine front, different sources of organic matter would support the food webs occurring in the three areas of the system. The particulate organic material (POM) would be the main resource supporting...
Tipo: Theses and Dissertations Palavras-chave: Food webs; Trophic relationships; Trophic levels; Saline fronts; Estuarine front; Carbon isotopes; Nitrogen isotopes; Plankton; Benthos; Brackishwater fish; Marine fish; Brackishwater environment; Marine environment.
Ano: 2012 URL: http://hdl.handle.net/1834/4523
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