Early to late Ediacaran conglomeratic wedges from a complete foreland basin cycle in the southwest São Francisco Craton, Bambuí Group, Brazil

Uhlein, Gabriel Jubé; Uhlein, Alexandre; Stevenson, Ross; Halverson, Galen P.; Caxito, Fabrício de Andrade; Cox, Grant

doi:10.1016/j.precamres.2017.07.020

Cited by 47 publications

(41 citation statements)

References 75 publications

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“…Constitui, segundo Alkmim et al (1993), a principal unidade neoproterozoica de cobertura do Cráton do São Francisco. As rochas do Grupo Bambuí representam ciclos transgressivo-regressivos em uma bacia foreland, na transição entre o cráton e a faixa móvel Brasília, em decorrência da sobrecarga gerada pela edificação de tal orógeno (Alkmim e Martins-Neto, 2001Uhlein et al, 2017b).…”

Section: Contexto Geológicounclassified

“…Baseando-se em estratigrafia de sequências, Uhlein et al (2017b) reconhecem cinco sequências transgressivo-regressivas de segunda ordem para o Grupo Bambuí, e os autores observam que a Formação Lagoa do Jacaré teria sido depositada durante ciclo regressivo, em uma rampa carbonática, com depósitos tempestíticos e calcários oolíticos associados.…”

Section: Contexto Geológicounclassified

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Caracterização em multiescala de carbonatos neoproterozóicos da Pedreira GMD, Formação Lagoa do Jacaré, Grupo Bambuí, Paraopeba-MG

Freitas

Uhlein

Dantas

et al. 2021

Geol. USP. Sér. Cient.

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O método Caracterização Multiescalar de Reservatórios (Camures) vem se consolidando como uma importante ferramenta e que tem auxiliado na caracterização dos mais diferentes tipos de afloramentos e seções de rochas sedimentares. O objetivo deste trabalho compreende a aplicação desse método em um afloramento da Formação Lagoa do Jacaré, Grupo Bambuí, representado por uma pedreira desativada na região de Paraopeba, centro-norte de Minas Gerais. Para tanto, utilizaram-se diferentes ferramentas investigativas em macro, meso e microescalas de análise para caracterização dessa unidade nesse afloramento. A caracterização litofaciológica de detalhe na pedreira revelou cinco litofácies carbonáticas principais. Dados geofísicos de Ground Penetrating Radar (GPR) e raios gama foram levantados para auxiliar no reconhecimento das principais geometrias e litologias presentes na área, bem como na correlação lateral dos perfis levantados na pedreira. A análise petrográfica microscópica mostra a ocorrência de seis fácies. A análise das litofácies e estruturas sedimentares presentes apontam para deposição sob influência de ondas de tempestade em diversos ciclos tempestíticos em plataforma carbonática rasa. Essa sequência é definida na base por brechas intraclásticas, representando momentos de alta energia, passando a momentos de menor energia que favorecem a deposição carbonática fina com estratificações hummocky e plano-paralelas, marcas onduladas associadas, até raros momentos de calmaria com deposição de sedimentos carbonáticos finos na transição antepraia-plataforma (shoreface-offshore).

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Section: Contexto Geológicounclassified

Caracterização em multiescala de carbonatos neoproterozóicos da Pedreira GMD, Formação Lagoa do Jacaré, Grupo Bambuí, Paraopeba-MG

Freitas

Uhlein

Dantas

et al. 2021

Geol. USP. Sér. Cient.

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“…This simple lithostratigraphic arrangement is valid mainly for the eastern and northern sectors of the basin. The southwestern and southern sectors bear a different lithostratigraphy and evidence suggesting a foreland‐type basin evolution for the Bambuí Basin (Reis & Suss, 2016; Uhlein et al., 2016, 2017).…”

Section: Geological Frameworkmentioning

confidence: 99%

Microbially induced chromium isotope fractionation and trace elements behavior in lower Cambrian microbialites from the Jaíba Member, Bambuí Basin, Brazil

et al. 2020

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In east‐central Brazil, the Ediacaran‐Cambrian Bambuí Basin has the potential to provide a record of unique geochemical responses of Earth's ocean and atmosphere evolution during this key time interval. From this perspective, we studied an interval of the upper Bambuí Basin using sedimentologic, stratigraphic, and chemostratigraphic tools. The lower Cambrian Jaíba Member of the uppermost Serra da Saudade Formation is an interval of up to 60 m‐thick of carbonate rocks disposed into two shallowing upward trends. Inner to outer ramp and high‐energy shoal deposits are described, in which laminated microbialites are the prevailing sedimentary facies. REE + Y data suggest contamination by iron (oxy)hydroxides that are dissociated from the riverine detritic flux. Sedimentary iron enrichment may be related to the settling of iron nanoparticles in coastal environments, diagenetic iron mobilization, or both. MREE enrichment is caused by microbial degradation of organic matter in the iron reduction zone during the anoxic early‐diagenetic stage. Chromium isotopes yielded negatively fractionated values (δ53Cr = −0.69 to −0.27‰), probably resulting from biotic and abiotic reduction of dissolved Cr(VI) to light and less toxic Cr(III) within pores of microbial mats. The δ53Cr data of the Jaíba microbialite are thus a product of metabolic reactions in microbial mats and do not reflect seawater signal. The isotopic offset from seawater is feasible from molecular diffusion of Cr into pore water and reduction reactions occurring deep inside the mat, although the exact mechanism and consequences are not yet fully understood due to the poor preservation of metabolic reactions in the geological record. Our study suggests that Cr isotopes can be used to reconstruct Cr and other metals cycling within ancient microbial mats, and that caution should be taken when using past microbialites to infer seawater Cr records and redox state of the atmosphere and ocean.

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“…The Bambuí Group corresponds to a siliciclastic and carbonate succession, deposited over three transgressiveregressive megacycles, in a basin that developed as a response to the Brasiliano orogenic cycle and the rise of the Brasília Fold Belt (Martins-Neto, 2007;Sial et al, 2009;Pimentel et al, 2011;Uhlein et al, 2017). The group covers vast areas of the São Francisco Craton and the Brasília Fold Belt, being present in over five Brazilian states, including Minas Gerais, Bahia, Goiás, Tocantins, and the Federal District territory (Dardenne, 2000).…”

Section: Introductionmentioning

confidence: 99%

Morphological and petrographic analysis of newly identified stromatolitic occurrences in the Lagoa do Jacaré Formation, Bambuí Group, State of Minas Gerais, Brazil

Santos¹,

Sanchez²,

Santucci³

2018

Rev. bras. paleontol

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Here we catalog, for the first time, the known stromatolite-containing localities and morphologies found in outcrops previously attributed, by past mapping efforts, to the Lagoa do Jacaré Formation, Bambuí Group. Unlike the Sete Lagoas Formation, which has already provided several crucial samples containing a substantial variety of microbialitic forms and microfossils, the fossiliferous potential of the Lagoa do Jacaré Formation has not been properly assessed. Surprisingly, a relatively diverse variety of forms was found, including domal, various columnar, laminites and columnar-layered stromatolites. Morphological and petrographical descriptions were made and six microfabrics were unveiled, shedding light into the environmental conditions likely to have been involved in their formation.

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Early to late Ediacaran conglomeratic wedges from a complete foreland basin cycle in the southwest São Francisco Craton, Bambuí Group, Brazil

Cited by 47 publications

References 75 publications

Caracterização em multiescala de carbonatos neoproterozóicos da Pedreira GMD, Formação Lagoa do Jacaré, Grupo Bambuí, Paraopeba-MG

Caracterização em multiescala de carbonatos neoproterozóicos da Pedreira GMD, Formação Lagoa do Jacaré, Grupo Bambuí, Paraopeba-MG

Microbially induced chromium isotope fractionation and trace elements behavior in lower Cambrian microbialites from the Jaíba Member, Bambuí Basin, Brazil

Morphological and petrographic analysis of newly identified stromatolitic occurrences in the Lagoa do Jacaré Formation, Bambuí Group, State of Minas Gerais, Brazil

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