Dados Isotópicos De Chumbo Em Sulfetos E a Evolução Metalogenética Dos Depósitos De Zinco E Chumbo Das Coberturas Neoproterozóicas Do Cráton Do São Francisco

Misi, Aroldo; Iyer, Brijesh; Tassinari, Colombo Celso Gaeta; Franca-Rocha, Washington; Coelho, Carlos Eduardo Silva; CUNHA, IONÁ DE ABREU; Gomes, Adriana S. Rocha

doi:10.25249/0375-7536.2004342263274

Cited by 10 publications

(6 citation statements)

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“…In fact, Pb-Pb isotope data of sulfides from these deposits either in South America or in Africa (Fig. 9), unambiguously indicate an upper crustal source for the metals (Burnard et al, 1993;Kamona et al, 1999;Misi et al, 2000Misi et al, , 2004Frimmel et al, 2004;Misi et al, 2005).…”

Section: Discussionmentioning

confidence: 72%

Supercontinent evolution and the Proterozoic metallogeny of South America

2007

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The cratonic blocks of South America have been accreted from 2.2 to 1.9 Ga, and all of these blocks have been previously involved in the assembly and breakup of the Paleoproterozoic Atlantica, the Mesoproterozoic to Neoproterozoic Rodinia, and the Neoproterozoic to Phanerozoic West Gondwana continents. Several mineralization phases have sequentially taken place during Atlantica evolution, involving Au, U, Cr, W, and Sn. During Rodinia assembly and breakup and Gondwana formation, the crust-dominated metallogenic processes have been overriding, responsible for several mineral deposits, including

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Section: Discussionmentioning

confidence: 72%

Supercontinent evolution and the Proterozoic metallogeny of South America

2007

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“…pointing to uplift-erosion of footwall and possibly hanging wall blocks twice in the evolution of the basin' (Dardenne 1978a(Dardenne , 1979(Dardenne , 1981D'el Rey Silva 1999, p. 463). Alkmim (1996) and Misi (1999) demonstrated the existence of widespread aligned structures with orientation 108N-208W intersecting both the older Proterozoic basement and the Neoproterozoic sedimentary cover (Fig. 48.1).…”

Section: Structural and Geotectonic Frameworkmentioning

confidence: 95%

Chapter 48 Neoproterozoic successions of the São Francisco Craton, Brazil: the Bambuí, Una, Vazante and Vaza Barris/Miaba groups and their glaciogenic deposits

Misi

Kaufman

Azmy

et al. 2011

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The Neoproterozoic successions of the São Francisco Craton are primarily represented by the Bambuí and Una groups, deposited in cratonic epicontinental basins, and by the Vazante and Vaza Barris/Miaba groups, which accumulated on passive margins on the edges of the craton. The epicontinental basins comprise three megasequences: glaciogenic, carbonate platform (marine) and dominantly continental siliciclastics. Possible correlative sequences are observed in the passive margin deposits. At least two major transgressive-regressive sea-level cycles occurred during the evolution of the carbonate megasequence, which lies above glaciomarine diamictites of probable early Cryogenian (i.e. Sturtian) age. C, O, Sr and S isotope trends from analyses of well-preserved samples, together with lithostratigraphic observations, provide reasonable correlations for most of the Neoproterozoic successions of the São Francisco Craton. The 87 Sr/ 86 Sr record of these successions, ranging from 0.70769 to 0.70780, supports the proposed correlation with the Bambuí, Una and Vaza/Barris successions, and with the basal units of the Vazante Group. In addition, C-isotope positive excursions ranging from þ8.7 to þ14‰ and negative excursions from -5.7 to -7‰ VPDB in the Bambuí, Una and Vaza-Barris successions provide key markers for correlations. The precise ages of the sedimentation in these successions remains a matter of debate, but organic shales of two units of the Vazante Group have been dated by Re-Os techniques in two different laboratories, both yielding Mesoproterozoic ages. The Neoproterozoic and Mesoproterozoic successions preserve significant glaciogenic deposits.

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“…Along the fault-bounded borders of the basin, oblique thrust faults acted as lateral ramps, with NW-SE trending dextral strike-slip faults on the western basin border and NE-SW trending sinistral strike-slip faults on the eastern basin border, thus suggesting a conjugate fault system. On the eastern basin border, oblique ramps contain Pb-and Zn-bearing minerals, barium and quartz veins (Cazarin et al, 2019(Cazarin et al, , 2021Kyle & Misi, 1997;Misi et al, 2004), which suggest external deeper hydrothermal fluid sources, possibly involving basement rocks.…”

Section: Geological Settingmentioning

confidence: 99%

Fault zone fluid pathways in the carbonate Irecê basin, NE Brazil

et al. 2022

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We applied field structural data and isotope geochemical (δ13C, δ18O and 87Sr/86Sr) analyses to understand the relationship among calcite veins, fault damage zones and carbonate host rocks in a thrust fault damage zone in the Achado quarry, Irecê Basin in the São Francisco Craton, NE Brazil. Our results reveal three hydrological packages with different rheological behaviours in a stratified carbonate succession. The upper package includes the Achado fault damage zone that is characterised by interlayered dolomitised grainstones and mudstones. These rocks display high positive δ13C values (10‰–13‰), negative δ18O values (mean −6.34‰) and radiogenic (87Sr/86Sr) isotope values (0.70885–0.71519). A second package is marked by a cataclastic brittle shear zone lateral parallel to dolograinstones bedding. These rocks show low to positive δ13C values (−3.41‰ to +8.85‰), more positive δ18O values (mean −3.73‰) and radiogenic (87Sr/86Sr) isotope values (0.71039–0.71373). The lower package is characterised by well‐preserved pristine limestone succession that shows δ13C values ranging between −0.46‰ and +3.17‰, mean δ18O = −5.41‰ and less radiogenic 87Sr/86Sr values (0.70762–0.70818). In contrast to the upper and intermediate packages, rocks from the lower one exhibit very low permeability and behaved as a seal for fluid migration. Fluid flow occurred several times during basin evolution, for example along syn‐rift fault damage zones, bedding‐parallel carbonate breccia, thrust faults, cataclastic shear zones, synorogenic conjugate shear fractures or joints and opening mode I fracture‐fill calcite veins. These fractures allowed pervasive fluid flow in the porous intermediate cataclastic shear zone where fluids flowed and formed veins, as diffuse fluid flow in randomly oriented fracture swarms, or channelised fluid flow in aligned fracture corridors. They record significant centimetre‐scale to km‐scale hydrological behaviour within carbonate layers. Most carbonates that are associated with veins, fault damage zones and hydraulic breccia were formed by fluids of the same origin with low δ13C (−6.0 to −2.0‰) and δ18O (−6.0 to −8.5‰) values, and more radiogenic 87Sr/86Sr values compared to the carbonate host rocks.

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Dados Isotópicos De Chumbo Em Sulfetos E a Evolução Metalogenética Dos Depósitos De Zinco E Chumbo Das Coberturas Neoproterozóicas Do Cráton Do São Francisco

Cited by 10 publications

References 0 publications

Supercontinent evolution and the Proterozoic metallogeny of South America

Supercontinent evolution and the Proterozoic metallogeny of South America

Chapter 48 Neoproterozoic successions of the São Francisco Craton, Brazil: the Bambuí, Una, Vazante and Vaza Barris/Miaba groups and their glaciogenic deposits

Fault zone fluid pathways in the carbonate Irecê basin, NE Brazil

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