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| 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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| 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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| 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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| 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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| Registros recuperados: 10 | |
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