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Paleoenvironmental interpretation through the analysis of ostracodes and carbonate microfacies: study of the Jandaíra Formation, Upper Cretaceous, Potiguar Basin
Paleoecological analyses are important tools for the reconstruction of paleoenvironments. This paper had the objective of using analysis of ostracode assemblages and carbonate microfacies of a well (Carbomil) and an outcrop (Quixeré) from the Jandaíra Formation, Potiguar Basin, in order to verify ho...
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Published in: | Brazilian journal of geology 2015-03, Vol.45 (1), p.23-34 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Paleoecological analyses are important tools for the reconstruction of paleoenvironments. This paper had the objective of using analysis of ostracode assemblages and carbonate microfacies of a well (Carbomil) and an outcrop (Quixeré) from the Jandaíra Formation, Potiguar Basin, in order to verify how they corroborate and complement the other. Two paleoenvironments for Carbomil Well (assemblages 1 and 2, respectively marine and brackish to neritic environments) and one for Quixeré Outcrop (assemblage 3, marine environment) were identified through the ostracode assemblage analysis. Thin section analysis allowed the identification of two different facies for Carbomil Well, i.e. bioclastic packstones to wackstones, a marine brackish or restricted marine system; and bioclastic grainstones to packstones, a normal, shallow marine system. High levels of alteration on the samples prevented an adequate analysis of Quixeré Outcrop; however, it seems to point towards a low-energy environment. Overall, information provided by the thin sections corroborate and complement data of the ostracode assemblages, which allowed a higher degree of certainty for the paleoenvironmental analysis.
Análises paleoecológicas são ferramentas importantes para a reconstrução de paleoambientes. Este trabalho teve como objetivo utilizar análises de associação de ostracodes e microfácies carbonáticas de um poço (Carbomil) e um afloramento (Ponto Quixeré) da Formação Jandaíra, Bacia Potiguar, a fim de verificar como estes métodos corroboram e complementam um ao outro. Dois paleoambientes para o Poço Carbomil (associações 1 e 2, respectivamente, ambiente marinho e mixo-halino) e um para o Ponto Quixeré (associação 3, ambiente marinho) foram identificados por meio da análise das associações de ostracodes. O estudo das seções petrográficas permitiu a identificação de duas fácies diferentes para o Poço Carbomil, packstonesa wackstonesbioclásticas, representando um sistema marinho salobro ou marinho restrito; grainstonesa packstonesbioclásticas, indicando um sistema marinho raso normal). As amostras do Ponto Quixeré parecem apontar para um ambiente de pouca energia. Em geral, as informações provenientes da análise das microfácies carbonáticas corroboram e complementam os dados fornecidos pelas assembleias de ostracodes, o que permitiu um maior grau de precisão na análise paleoambiental. |
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ISSN: | 2317-4889 2317-4692 2317-4889 |
DOI: | 10.1590/23174889201500010002 |