Meso-Neoproterozoic isotope stratigraphy on carbonates platforms in the Brasilia Belt of Brazil

Alvarenga, Carlos J. S.; Santos, Roberto Ventura; Vieira, Lucieth Cruz; Lima, Bárbara; Mancini, L.

doi:10.1016/j.precamres.2014.06.011

Cited by 67 publications

(69 citation statements)

References 51 publications

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“…values are correlated with those obtained by Kuchenbecker (2011), Alvarenga et al (2014), Warren et al (2014) and Paula Santos et al (2015) at the unit base. These carbonates are characterized by sedimentary structures as rhythmic lamination interlayered with pelites, clays and truncated irregular laminations, possibly associated with tidal shallow marine environment, typically attributed to Pedro Leopoldo Member described by Schöll (1976), Ribeiro et al (2003), Vieira et al (2007a, b) and Paula- Santos et al (2015), corresponding to the lower Sete Lagoas Formation.…”

Section: And O Isotopic Variationssupporting

confidence: 81%

“…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: 62%

“…The 87 Sr/ 86 Sr ratios between 0.7074 and 0.7080 indicate ambiguity in the age of the Bambuí Group (Misi et al, 2007;Babinski et al, 2007;Kuchenbecker, 2011;Alvarenga et al, 2014;Paula-Santos et al, 2015) in comparison with the seawater Sr isotope evolution curves proposed in literature (Jacobsen & Kaufman, 1999;Melezhik et al, 2001;Halverson et al, 2010;Kuznetsov et al, 2013). Considering the maximum depositional age of 560 Ma, such Sr isotope ratios are lower than the ones expected for the terminal Ediacaran.…”

Section: Introductionmentioning

confidence: 62%

“…Low radiogenic 87 Sr/ 86 Sr ratios between 0.7074 and 0.7080 have been reported for the Sete Lagoas Formation (Misi & Veizer 1998;Misi et al, 2007;Babinski et al, 2007;Kuchenbecker, 2011;Alvarenga et al, 2014, Paula-Santos et al, 2015. The latter authors suggest that the difference between the low radiogenic 87 Sr/ 86 Sr ratios commonly obtained for Bambuí Group and the ratios presented for the late Neoproterozoic (Melezhik et al, 2001;Halverson et al, 2010;Kuznetsov et al, 2013) may be due to the fact that carbonates of the Sete Lagoas Formation have been deposited in a restricted epi-continental sea, and its isotopic composition was not homogenized with contemporary global oceans (Paula- Santos et al, 2015).…”

Section: The Sete Lagoas Formationmentioning

confidence: 94%

“…However, some authors propose that the Sete Lagoas Formation represents a cap carbonate sequence of early Ediacaran age deposited after the Marinoan glaciation, based on global correlations via isotope chemostratigraphy (i.e. Caxito et al, 2012;Alvarenga et al, 2014;Uhlein et al, 2016). To add more pieces to the puzzle, recent biostratigraphic data indicate ages of 553-542 Ma in the middle part of the sequence based on Cloudina fossil (Warren et al, 2014), which suggest a late Ediacaran age for the Sete Lagoas Formation.…”

Section: Introductionmentioning

confidence: 99%

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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: 81%

Section: The Sete Lagoas Formationmentioning

confidence: 62%

Section: Introductionmentioning

confidence: 62%

Section: The Sete Lagoas Formationmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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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Chemostratigraphy of the Mesoproterozoic‐Neoproterozoic Transition

Silva-Tamayo

Nova

Dussan-Tapias

2018

Chemostratigraphy Across Major Chronological Boundaries

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Mineralogical and geochemical constraints on the provenance and depositional setting of Sri Lankan marbles

Madugalla

Pitawala

2021

Geological Journal

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Proterozoic high‐grade marbles cover a significant portion of the Highland Complex (HC) of Sri Lanka. Although many studies on metamorphic silicate rocks of the country have been carried out, marbles, which can be used as a tool to interpret the evolution history of the crust, has been paid little attention. The present study aims to understand the genesis and characteristics of protolith of these marbles by investigating their mineralogy and geochemistry. The studied marbles occur as bands intercalated with pelitic gneisses and quartzites of the HC, indicating the pre‐existing sandstone‐shale‐carbonate sedimentary sequence. Except along the lithological contacts, the studied marbles contain low amounts of silicate minerals (<5%) and are dominated by dolomites (>90%) with minor calcites. Calcites occur as inclusions within dolomites or as fine grains along the grain boundaries of dolomites. Silicate minerals always occur as lensoid or layered aggregations. Dolomites are related to the protolith composition, while most of the calcites are metamorphic products formed due to the reaction of silicate minerals with dolomite. Silicate mineralogical zones suggest the inherited compositional variations of the protolith. Although the marbles have undergone granulite‐grade metamorphism, their trace elemental contents have been well preserved. Concentrations of Fe, Mn, Sr, Na, and K as well as rare earth element (REE) contents of the marbles are comparable to those of marine origin carbonates. Hence, marine dolostone can be proposed as the protolith for Sri Lankan marbles. The distinct mineralogy as well as elevated trace element and REE concentrations of marble in the lithological contact zones are evidenced for prevailed syn‐ to post‐metamorphic fluid activities in the HC. Mineralogical and trace elemental composition of Sri Lankan marbles are correlated well with the marbles from other East‐Gondwanaland crustal units.

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Meso-Neoproterozoic isotope stratigraphy on carbonates platforms in the Brasilia Belt of Brazil

Cited by 67 publications

References 51 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

Chemostratigraphy of the Mesoproterozoic‐Neoproterozoic Transition

Mineralogical and geochemical constraints on the provenance and depositional setting of Sri Lankan marbles

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