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	Provedor de dados Anais da ABC (AABC) (2) Autor DACOSTA,MARCONDES L. (1) DEALMEIDA,AFONSO R. (1) FERREIRA,VALDEREZ P. (1) Ferreira,Valderez P. (1) PARENTE,CLOVIS V. (1) Pimentel,Márcio M. (1) ROMANO,ANTONIO W. (1) SANTOS,VICTOR H. (1) SIAL,ALCIDES N. (1) Sial,Alcides N. (1) Silva,Juan C. (1) Mais... Palavra-chave Chemostratigraphy (2) Archean (1) Borborema Province (1) C-isotopes (1) Carbon isotopes (1) Carbonates (1) Meso-Neoproterozoic (1) Neoproterozoic (1) Northeastern Brazil (1) Paleoproterozoic (1) Mais... Tipo do documento Info:eu-repo/semantics/article (2) Ano 2005 (1) 2000 (1) País Brazil (2) Idioma Inglês (2)		Ordenar por:  Relevância Autor Título Ano Registros recuperados: 2 Primeira ... 1 ... Última C- and Sr-isotope stratigraphy of the São Caetano complex, Northeastern Brazil: a contribution to the study of the Meso-Neoproterozoic seawater geochemistry Anais da ABC (AABC) Silva,Juan C.; Sial,Alcides N.; Ferreira,Valderez P.; Pimentel,Márcio M.. C-isotope and 87Sr/86Sr values for five carbonate successions from the São Caetano Complex, northeastern Brazil, were used to constrain their depositional age and to determine large variations in the C- and Sr-isotopic composition of seawater under the framework of global tectonic events. Three C-isotope stages were identified from base to top in a composed chemostratigraphic section: (1) stage in which delta13C values vary from +2 to +3.7‰ PDB and average 3‰ PDB, (2) stage with delta13C values displaying stronger oscillations (from -2‰ to +‰ PDB), and (3) stage with an isotopic plateau with values around +3.7‰ PDB. Constant 87Sr/86Sr values (~ 0.70600) characterize C-isotope stage 1, whereas slightly fluctuating values (from 0.70600 to 0.70700)... Tipo: Info:eu-repo/semantics/article Palavras-chave: C-isotopes; Meso-Neoproterozoic; Chemostratigraphy; Borborema Province; Northeastern Brazil. Ano: 2005 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652005000100011 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 Registros recuperados: 2 Primeira ... 1 ... Última

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