Artigo

Carbon and oxygen isotope geochemistry of Ediacaran outer platform carbonates, Paraguay Belt, central Brazil

After the late Cryogenian glaciation the central region of Brazil was the site of extensive deposition of platformal carbonates of the Araras Group. This group includes a basal cap carbonate sequence succeeded by transgressive, deep platform deposits of bituminous lime mudstone and shale. Facies and...

ver descrição completa

Autor principal: RICCOMINI, Claudio
Outros Autores: NOGUEIRA, Afonso César Rodrigues, SIAL, Alcides Nóbrega
Grau: Artigo
Idioma: eng
Publicado em: 2011
Assuntos:
Oxigênio
Glaciação
Amazônia brasileira
Carbono
Isótopos
Geoquímica
Grupo Araras
Crátons
Acesso em linha: http://www.repositorio.ufpa.br:8080/jspui/handle/2011/2368
id ir-2011-2368
recordtype dspace
spelling ir-2011-23682019-05-23T13:25:53Z Carbon and oxygen isotope geochemistry of Ediacaran outer platform carbonates, Paraguay Belt, central Brazil RICCOMINI, Claudio NOGUEIRA, Afonso César Rodrigues SIAL, Alcides Nóbrega Oxigênio Glaciação Amazônia brasileira Carbono Isótopos Geoquímica Grupo Araras Crátons After the late Cryogenian glaciation the central region of Brazil was the site of extensive deposition of platformal carbonates of the Araras Group. This group includes a basal cap carbonate sequence succeeded by transgressive, deep platform deposits of bituminous lime mudstone and shale. Facies and stratigraphic data combined with carbon and oxygen isotopic analyses of the most complete section of the transgressive deposits, exposed in the Guia syncline, were used to evaluate the depositional paleoenvironment and to test the correlation of these deposits along the belt and with other units worldwide. The studied succession consists of 150 m thick tabular beds of black to grey lime mudstone and shale with predominantly negative d13CPDB values around –2.5 to -1 . The d13CPDB profile of Guia syncline shows a clear correlation with the upper portion of Guia Formation in the Cáceres region, about 200 km to the southwest. The d13CPDB profile of the Araras Group is comparable with d13CPDB profiles of Ediacaran units of the southern Paraguay Belt, western Canada, and the Congo and Kalahari cratons. Moreover, facies distribution, stratigraphy and the carbon isotopic profile of the Araras Group match the middle Tsumeb Subgroup in Namibia, which reinforces the Ediacaran age assigned to the Araras Group. Após a glaciação do final do Criogeniano, a região central do Brasil foi palco de extensa deposição de carbonatos plataformais do Grupo Araras. Este grupo inclui na sua base uma seqüência de capa carbonática sucedida por depósitos transgressivos de calcilutitos betuminosos e folhelhos de plataforma profunda. Dados de fácies e estratigráficos combinados com análises isotópicas de carbono e oxigênio da seção mais completa desses depósitos transgressivos, expostos no sinclinal da Guia, foram empregados para avaliar o paleambiente deposicional e para testar a correlação desses depósitos ao longo da faixa e também com outras unidades de outros continentes. A sucessão estudada consiste de 150 m de espessura de camadas tabulares de calcilutitos e folhelhos cinza a pretos com valores de d13CPDB negativos, entre -2,5 e -1 . O perfil de d13CPDB do sinclinal da Guia mostra clara correlação com a porção superior da Formação Guia da região de Cáceres, 200 km a sudoeste. O perfil de d13CPDB do Grupo Araras é comparável aos perfis de d13CPDB de outras unidades ediacaranas da parte sul da Faixa Paraguai, oeste do Canadá, e crátons do Congo e do Kalahari. Além disso, a distribuição de fácies, estratigrafia e o perfil isotópico do Grupo Araras são equiparáveis à porção média do Subgrupo Tsumeb na Namíbia, o que reforça a atribuição de idade Ediacarana para o Grupo Araras. 2011-11-10T17:03:57Z 2011-11-10T17:03:57Z 2007-09 Artigo de Periódico RICCOMINI, Claudio; NOGUEIRA, Afonso C.R.; SIAL, Alcides N. Carbon and oxygen isotope geochemistry of Ediacaran outer platform carbonates, Paraguay Belt, central Brazil. Anais da Academia Brasileira de Ciências, Rio de Janeiro, v. 79, n. 3, p. 519-527, set. 2007. Disponível em: <http://www.scielo.br/pdf/aabc/v79n3/a12v79n3.pdf>. Acesso em: 10 nov. 2011. http://dx.doi.org/10.1590/S0001-37652007000300012. 0001-3765 http://www.repositorio.ufpa.br:8080/jspui/handle/2011/2368 eng Acesso Aberto application/pdf
institution Repositório Institucional - Universidade Federal do Pará
collection RI-UFPA
language eng
topic Oxigênio
Glaciação
Amazônia brasileira
Carbono
Isótopos
Geoquímica
Grupo Araras
Crátons
spellingShingle Oxigênio
Glaciação
Amazônia brasileira
Carbono
Isótopos
Geoquímica
Grupo Araras
Crátons
RICCOMINI, Claudio
Carbon and oxygen isotope geochemistry of Ediacaran outer platform carbonates, Paraguay Belt, central Brazil
topic_facet Oxigênio
Glaciação
Amazônia brasileira
Carbono
Isótopos
Geoquímica
Grupo Araras
Crátons
description After the late Cryogenian glaciation the central region of Brazil was the site of extensive deposition of platformal carbonates of the Araras Group. This group includes a basal cap carbonate sequence succeeded by transgressive, deep platform deposits of bituminous lime mudstone and shale. Facies and stratigraphic data combined with carbon and oxygen isotopic analyses of the most complete section of the transgressive deposits, exposed in the Guia syncline, were used to evaluate the depositional paleoenvironment and to test the correlation of these deposits along the belt and with other units worldwide. The studied succession consists of 150 m thick tabular beds of black to grey lime mudstone and shale with predominantly negative d13CPDB values around –2.5 to -1 . The d13CPDB profile of Guia syncline shows a clear correlation with the upper portion of Guia Formation in the Cáceres region, about 200 km to the southwest. The d13CPDB profile of the Araras Group is comparable with d13CPDB profiles of Ediacaran units of the southern Paraguay Belt, western Canada, and the Congo and Kalahari cratons. Moreover, facies distribution, stratigraphy and the carbon isotopic profile of the Araras Group match the middle Tsumeb Subgroup in Namibia, which reinforces the Ediacaran age assigned to the Araras Group.
format Artigo
author RICCOMINI, Claudio
author2 NOGUEIRA, Afonso César Rodrigues
SIAL, Alcides Nóbrega
author2Str NOGUEIRA, Afonso César Rodrigues
SIAL, Alcides Nóbrega
title Carbon and oxygen isotope geochemistry of Ediacaran outer platform carbonates, Paraguay Belt, central Brazil
title_short Carbon and oxygen isotope geochemistry of Ediacaran outer platform carbonates, Paraguay Belt, central Brazil
title_full Carbon and oxygen isotope geochemistry of Ediacaran outer platform carbonates, Paraguay Belt, central Brazil
title_fullStr Carbon and oxygen isotope geochemistry of Ediacaran outer platform carbonates, Paraguay Belt, central Brazil
title_full_unstemmed Carbon and oxygen isotope geochemistry of Ediacaran outer platform carbonates, Paraguay Belt, central Brazil
title_sort carbon and oxygen isotope geochemistry of ediacaran outer platform carbonates, paraguay belt, central brazil
publishDate 2011
url http://www.repositorio.ufpa.br:8080/jspui/handle/2011/2368
_version_ 1832602980912726016
score 11.755432

Registros relacionados