Carbon isotope fluctuations in Precambrian carbonate sequences of several localities in Brazil

Detalhes bibliográficos
Autor(a) principal: Sial, Alcides N.
Data de Publicação: 2000
Outros Autores: Ferreira, Valderez P., Almeida, Afonso Rodrigues de, Romano, Antonio W., Parente, Clóvis Vaz, Costa, Marcondes L. da, Santos, Victor H.
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
Texto Completo: http://www.repositorio.ufc.br/handle/riufc/64128
Resumo: 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, state of Ceará, exhibit carbon isotope fluctuation within the range for carbonates deposited at 1.8 Ga. The C-isotope record of the Frecheirinha Formation, northwestern state of Ceará, shows negative delta13C values in its lower portion (-2 o/oo) and positive values up section (+1 to +3 o/oo), which suggests this sequence is a cap carbonate deposited after a glacial event around 0.95 Ga. The Jacoca and Acauã sedimentary carbonate Formations, state of Sergipe, NE Brazil, show carbon isotope fluctuations very similar to each other (average around -5 o/oo), compatible with a deposition around 0.76 Ga. The younger Olho D'Água carbonate Formation, however, also in the state of Sergipe, displays negative delta13C values at the lower portion of the Formation, changing dramatically up section to positive values as high as +10 o/oo, a characteristic compatible with a Sturtian cap carbonate deposited around 0.69 Ga. On the light of the C isotope data discussed in this study, it seems that delta13C fluctuations in Paleoproterozoic carbonates in Brazil are within the range found globally for metasedimentary carbonates of this age. Carbon isotope data proved to be very useful in establishing relative chronology of Neoproterozoic carbonate formations for which precise radiometric ages are not available.
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spelling Carbon isotope fluctuations in Precambrian carbonate sequences of several localities in BrazilCarbon isotopesCarbonatesChemostratigraphyArcheanPaleoproterozoicNeoproterozoicCarbon 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, state of Ceará, exhibit carbon isotope fluctuation within the range for carbonates deposited at 1.8 Ga. The C-isotope record of the Frecheirinha Formation, northwestern state of Ceará, shows negative delta13C values in its lower portion (-2 o/oo) and positive values up section (+1 to +3 o/oo), which suggests this sequence is a cap carbonate deposited after a glacial event around 0.95 Ga. The Jacoca and Acauã sedimentary carbonate Formations, state of Sergipe, NE Brazil, show carbon isotope fluctuations very similar to each other (average around -5 o/oo), compatible with a deposition around 0.76 Ga. The younger Olho D'Água carbonate Formation, however, also in the state of Sergipe, displays negative delta13C values at the lower portion of the Formation, changing dramatically up section to positive values as high as +10 o/oo, a characteristic compatible with a Sturtian cap carbonate deposited around 0.69 Ga. On the light of the C isotope data discussed in this study, it seems that delta13C fluctuations in Paleoproterozoic carbonates in Brazil are within the range found globally for metasedimentary carbonates of this age. Carbon isotope data proved to be very useful in establishing relative chronology of Neoproterozoic carbonate formations for which precise radiometric ages are not available.Anais da Academia Brasileira de Ciências2022-02-23T14:57:53Z2022-02-23T14:57:53Z2000info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfSIAL, Alcides N. et al. Carbon isotope fluctuations in Precambrian carbonate sequences of several localities in Brazil. Anais da Academia Brasileira de Ciências, Rio de Janeiro, v. 72, n. 4, p. 539-558, 2000.1678-2690http://www.repositorio.ufc.br/handle/riufc/64128Sial, Alcides N.Ferreira, Valderez P.Almeida, Afonso Rodrigues deRomano, Antonio W.Parente, Clóvis VazCosta, Marcondes L. daSantos, Victor H.info:eu-repo/semantics/openAccessengreponame:Repositório Institucional da Universidade Federal do Ceará (UFC)instname:Universidade Federal do Ceará (UFC)instacron:UFC2023-10-10T17:33:57Zoai:repositorio.ufc.br:riufc/64128Repositório InstitucionalPUBhttp://www.repositorio.ufc.br/ri-oai/requestbu@ufc.br || repositorio@ufc.bropendoar:2024-09-11T18:58:07.842452Repositório Institucional da Universidade Federal do Ceará (UFC) - Universidade Federal do Ceará (UFC)false
dc.title.none.fl_str_mv Carbon isotope fluctuations in Precambrian carbonate sequences of several localities in Brazil
title Carbon isotope fluctuations in Precambrian carbonate sequences of several localities in Brazil
spellingShingle Carbon isotope fluctuations in Precambrian carbonate sequences of several localities in Brazil
Sial, Alcides N.
Carbon isotopes
Carbonates
Chemostratigraphy
Archean
Paleoproterozoic
Neoproterozoic
title_short Carbon isotope fluctuations in Precambrian carbonate sequences of several localities in Brazil
title_full Carbon isotope fluctuations in Precambrian carbonate sequences of several localities in Brazil
title_fullStr Carbon isotope fluctuations in Precambrian carbonate sequences of several localities in Brazil
title_full_unstemmed Carbon isotope fluctuations in Precambrian carbonate sequences of several localities in Brazil
title_sort Carbon isotope fluctuations in Precambrian carbonate sequences of several localities in Brazil
author Sial, Alcides N.
author_facet Sial, Alcides N.
Ferreira, Valderez P.
Almeida, Afonso Rodrigues de
Romano, Antonio W.
Parente, Clóvis Vaz
Costa, Marcondes L. da
Santos, Victor H.
author_role author
author2 Ferreira, Valderez P.
Almeida, Afonso Rodrigues de
Romano, Antonio W.
Parente, Clóvis Vaz
Costa, Marcondes L. da
Santos, Victor H.
author2_role author
author
author
author
author
author
dc.contributor.author.fl_str_mv Sial, Alcides N.
Ferreira, Valderez P.
Almeida, Afonso Rodrigues de
Romano, Antonio W.
Parente, Clóvis Vaz
Costa, Marcondes L. da
Santos, Victor H.
dc.subject.por.fl_str_mv Carbon isotopes
Carbonates
Chemostratigraphy
Archean
Paleoproterozoic
Neoproterozoic
topic Carbon isotopes
Carbonates
Chemostratigraphy
Archean
Paleoproterozoic
Neoproterozoic
description 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, state of Ceará, exhibit carbon isotope fluctuation within the range for carbonates deposited at 1.8 Ga. The C-isotope record of the Frecheirinha Formation, northwestern state of Ceará, shows negative delta13C values in its lower portion (-2 o/oo) and positive values up section (+1 to +3 o/oo), which suggests this sequence is a cap carbonate deposited after a glacial event around 0.95 Ga. The Jacoca and Acauã sedimentary carbonate Formations, state of Sergipe, NE Brazil, show carbon isotope fluctuations very similar to each other (average around -5 o/oo), compatible with a deposition around 0.76 Ga. The younger Olho D'Água carbonate Formation, however, also in the state of Sergipe, displays negative delta13C values at the lower portion of the Formation, changing dramatically up section to positive values as high as +10 o/oo, a characteristic compatible with a Sturtian cap carbonate deposited around 0.69 Ga. On the light of the C isotope data discussed in this study, it seems that delta13C fluctuations in Paleoproterozoic carbonates in Brazil are within the range found globally for metasedimentary carbonates of this age. Carbon isotope data proved to be very useful in establishing relative chronology of Neoproterozoic carbonate formations for which precise radiometric ages are not available.
publishDate 2000
dc.date.none.fl_str_mv 2000
2022-02-23T14:57:53Z
2022-02-23T14:57:53Z
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
format article
status_str publishedVersion
dc.identifier.uri.fl_str_mv SIAL, Alcides N. et al. Carbon isotope fluctuations in Precambrian carbonate sequences of several localities in Brazil. Anais da Academia Brasileira de Ciências, Rio de Janeiro, v. 72, n. 4, p. 539-558, 2000.
1678-2690
http://www.repositorio.ufc.br/handle/riufc/64128
identifier_str_mv SIAL, Alcides N. et al. Carbon isotope fluctuations in Precambrian carbonate sequences of several localities in Brazil. Anais da Academia Brasileira de Ciências, Rio de Janeiro, v. 72, n. 4, p. 539-558, 2000.
1678-2690
url http://www.repositorio.ufc.br/handle/riufc/64128
dc.language.iso.fl_str_mv eng
language eng
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Anais da Academia Brasileira de Ciências
publisher.none.fl_str_mv Anais da Academia Brasileira de Ciências
dc.source.none.fl_str_mv reponame:Repositório Institucional da Universidade Federal do Ceará (UFC)
instname:Universidade Federal do Ceará (UFC)
instacron:UFC
instname_str Universidade Federal do Ceará (UFC)
instacron_str UFC
institution UFC
reponame_str Repositório Institucional da Universidade Federal do Ceará (UFC)
collection Repositório Institucional da Universidade Federal do Ceará (UFC)
repository.name.fl_str_mv Repositório Institucional da Universidade Federal do Ceará (UFC) - Universidade Federal do Ceará (UFC)
repository.mail.fl_str_mv bu@ufc.br || repositorio@ufc.br
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