Carbon isotopes of Mesoproterozoic–Neoproterozoic sequences from Southern São Francisco craton and Araçuaí Belt, Brazil: Paleographic implications

Santos, Roberto Ventura; Alvarenga, Carlos J. S.; Babinski, Marly; Ramos, Maria Luiza S.; Cukrov, Neven; Fonseca, Marco Antônio; Sial, Alcides da Nóbrega; Dardenne, Marcel Auguste; Noce, Carlos Maurício

doi:10.1016/j.jsames.2004.08.009

Cited by 51 publications

(46 citation statements)

References 32 publications

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“…These values are interpreted as representative of the depositional environment and can be correlated with those obtained by Santos et al (2004) and Vieira et al (2007b) in carbonates from the first depositional sequence of the Sete Lagoas Formation, which were above the cap carbonate with negative δ 13 C values around -4.5‰ and below the positive C isotopic shift (Fig. 5).…”

Section: And O Isotopic Variationssupporting

confidence: 79%

“…They confirm δ 13 C values as representative of the isotopic seawater composition at the time of deposition. These isotopic data correlate with the δ 13 C values obtained by Santos et al (2004), Vieira et al (2007b) and Paula-Santos et al (2015), which suggest that the SL and HV sections are positioned above the characteristic C isotopic shift from the upper Sete Lagoas Formation (Fig. 5).…”

Section: And O Isotopic Variationssupporting

confidence: 77%

“…These limestones are overlaid by carbonates with wavy and microbial structures deposited in coastal areas with very positive δ 13 C values that reach +16‰ (Iyer et al, 1995). This significant increase in the δ 13 C values from the base to the top of the Sete Lagoas Formation was also reported by Santos et al (2000Santos et al ( , 2004, Misi et al (2007), Alvarenga et al (2014) and Paula-Santos et al (2015).…”

Section: The Sete Lagoas Formationmentioning

confidence: 61%

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C, O, and Sr isotopic variations in Neoproterozoic-Cambrian carbonate rocks from Sete Lagoas Formation (Bambuí Group), in the Southern São Francisco Basin, Brazil

et al. 2017

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High-resolution chemostratigraphic data of carbonates from the Sete Lagoas Formation (Bambuí Group) show large variations on the C, O, and Sr isotope compositions. Impure limestones at the base show primal δ 13 C values between -1.0 and 0‰, and δ 18 O values between -12.0 and -8.0‰. However, some dolostones demonstrate δ 13 C values varying from +2.8 to -6.8‰, highly radiogenic 87 Sr/ 86 Sr ratios (>0.7111), and low Sr concentrations (<350 ppm) related to post-depositional processes. In contrast, pure limestones at the top show very positive δ 13 C values between +8.3 and +12.8‰, δ 18 O values between -10.0 to -6.0‰, and 87 Sr/ 86 Sr ratios from 0.7073 to 0.7086, with high Sr concentrations (>900 ppm). They are linked to depositional controls on the carbonate platform, such as fluvial and/or submarine water influx, in which carbonates deposited on the proximal sector exhibit significant Sr isotopic variations and those on the distal sector were not subject to such controls, resulting in very homogeneous Sr isotope profiles. However, 87 Sr/ 86 Sr ratios of the distal carbonates are less radiogenic than carbonates expected for late Ediacaran (~0.7085). This discrepancy suggests a restricted marine basin without Sr isotopic homogenization with contemporary oceans and, in this case, global correlations based on Sr isotope stratigraphy are not reliable. KEYWORDS:Isotopes; Carbonates; Bambuí Group; Ediacaran. RESUMO: Dados quimioestratigráficos de alta resolução em carbonatos da Formação Sete Lagoas (Grupo Bambuí) apresentam grandes variações nas composições isotópicas de C, O e Sr. Os calcários impuros na base da unidade mostram valores primários de

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Section: And O Isotopic Variationssupporting

confidence: 79%

Section: And O Isotopic Variationssupporting

confidence: 77%

Section: The Sete Lagoas Formationmentioning

confidence: 61%

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C, O, and Sr isotopic variations in Neoproterozoic-Cambrian carbonate rocks from Sete Lagoas Formation (Bambuí Group), in the Southern São Francisco Basin, Brazil

et al. 2017

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“…C between -5 and +5‰ in gray limestones or dolostone of the Sete Lagoas Formation, Bambuí Group, jump to 10‰ towards the upper part of this stratigraphic unit (Ramos 2000, Santos et al 2004, Vieira et al 2007, Martins and Lemos 2007. C-isotope values observed in laminated limestones of the Rodeador quarry suggest that these rocks belong to the middle portion of the Sete Lagoas Formation, prior to the positive isotopic excursion characteristic of the top of this formation (Fig.…”

mentioning

confidence: 94%

C-, Sr-isotope stratigraphy of carbonate rocks from the Southern Espinhaço Ridge, Minas Gerais, southeastern Brazil

Fraga

Neves

Uhlein

et al. 2014

An. Acad. Bras. Ciênc.

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Neoproterozoic carbonate rocks comprise different stratigraphic units in the southern part of the Espinhaço Ridge, Minas Gerais, Brazil. C, O-and Sr-isotope analyses were carried out along four selected stratigraphic sections across these formations. Sr observed in carbonate samples from the Macaúbas Group are similar to those observed in the Sr-isotope secular curve for the Neoproterozoic. Carbonate samples from the base of the Bambuí Group correlate with Ediacaran fingerprints, after the Marinoan (ca. 635 Ma) glaciation.

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“…Other pioneer chemostratigraphic investigations in Brazil were performed by Torquato (1980), Zaine (1991), Sial et al (1992), Chang et al (1994), Misi & Kyle (1994), Kawashita (1996), Boggiani et al (1996), Chang (1997), Santos et al (2000Santos et al ( , 2004, and Sial et al (2000). Zaine (1991) has measured C and O isotope ratios in carbonates of the Tamengo Formation, Corumbá Group, and Boggiani et al (1996) have identified an upper Ediacaran positive δ 13 C excursion, associated to the occurrence of Cloudina, which was correlated with the Arroyo del Soldado Group in Uruguay (Gaucher 1999).…”

mentioning

confidence: 99%

Correlations of some Neoproterozoic carbonate-dominated successions in South America based on high-resolution chemostratigraphy

Sial

Gaucher²,

Misi

et al. 2016

Braz. J. Geol.

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This report reviews and incorporates new elemental and isotope chemostratigraphic data for correlation of Neoproterozoic carbonate-dominated successions in South America (Argentina, Bolivia, Brazil, Paraguay and Uruguay). These thick mixed carbonate/siliciclastic successions were largely deposited in epicontinental basins or accumulated on passive margins on the edges of cratons (e.g. São Francisco, Amazonia, Rio Apa Block, Pampia and Río de la Plata paleocontinents) during extensional events related to the rifting of the Rodinia Supercontinent. From the stratigraphic point of view, these successions occur as three mega-sequences: glaciogenic, marine carbonate platform (above glaciomarine diamictites or rift successions), and dominantly continental to transitional siliciclastics. In the orogenic belts surrounding cratons, carbonate-dominated successions with important volcanoclastic/siliciclastic contribution have been, in most cases, strongly deformed. The precise ages of these successions remain a matter of debate, but recently new paleontological and geochronological data have considerably constrained depositional intervals. Here, we report high-resolution C, O, Sr, and S isotope trends measured in well-preserved sample sets and mainly use Sr and C isotopes RESUMO: Esta revisão incorpora novos dados isotópicos e quími-cos para correlação quimioestratigráfica de sucessões

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Carbon isotopes of Mesoproterozoic–Neoproterozoic sequences from Southern São Francisco craton and Araçuaí Belt, Brazil: Paleographic implications

Cited by 51 publications

References 32 publications

C, O, and Sr isotopic variations in Neoproterozoic-Cambrian carbonate rocks from Sete Lagoas Formation (Bambuí Group), in the Southern São Francisco Basin, Brazil

C, O, and Sr isotopic variations in Neoproterozoic-Cambrian carbonate rocks from Sete Lagoas Formation (Bambuí Group), in the Southern São Francisco Basin, Brazil

C-, Sr-isotope stratigraphy of carbonate rocks from the Southern Espinhaço Ridge, Minas Gerais, southeastern Brazil

Correlations of some Neoproterozoic carbonate-dominated successions in South America based on high-resolution chemostratigraphy

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