U-Pb, Rb-Sr and Sm-Nd chronology of granitic basement, hydrothermal albitites and uranium mineralization (Lagoa Real, South-Bahia, Brazil)

Turpin, Laurent; Maruéjol, Patricia; Cuney, Michel

doi:10.1007/bf00402107

Cited by 104 publications

(110 citation statements)

References 22 publications

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“…This intrusive suite includes predominantly syenites, syenogranites and alkali-feldspar granites, which are leucocratic and mostly either porphyritic or medium phaneritic in their texture (Cruz et al 2007b). The crystallization age of these rocks is around 1.7 Ga (Turpin et al 1988, Cordani et al 1992, Cruz et al 2007b.…”

Section: Regional Geological Contextmentioning

confidence: 99%

Tectonic inversion of compressional structures in the Southern portion of the Paramirim Corridor, Bahia, Brazil

et al. 2015

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ABSTRACT:The Paramirim Corridor represents the maximum inversion zone of the Paramirim Aulacogen. Reverse-to-reverse dextral shear zones and various types of folds dominate such corridor. These structures reflect a stress field that is WSW-ENE oriented, developed in units of Aulacogen basement, as well as in the Lagoa Real Intrusive Suite, of Statherian age, in Espinhaço and São Francisco supergroups, of Statherian-Tonian and Cryogenian ages, respectively, and in the Macaúbas-Santo Onofre Group, of Tonian age at the most. A rich collection of extensional structures truncate compressional structures of the Paramirim Corridor, characterized by normal shear zones and foliation, which is sometimes mylonitic, down-dip stretching lineation, drag folds, traction fractures and S/C structures. In these shear zones, quartz occurs truncated by the foliation, while feldspars are fractured and altered to white mica. Distribution of the quartz c-axes is at a maximum of 14° from the Z-axis. Thus, it suggests that the deformation activated mainly the basal glide planes in the direction. The paleostress study using the Win-Tensor software demonstrated that the regimen ranged between radial and pure distention. The S 1 direction oscillated around a vertical trend, while s 3 was sub-horizontal, with a predominant N230-050° direction. Ar-Ar ages in biotite obtained from the extensional shear zones ranged from 480 and 490 Ma. Together, data obtained for the structures associated with the late extensional regimen described in the present study suggest that its nucleation is associated with distal and brittle-ductile sectors of the gravitational collapse zone of Araçuaí-West Congo Orogen.KEYWORDS: Shear Zone; Paramirim Corridor; Gravitational Collapse. RESUMO: O Corredor do Paramirim representa a zona de máxima inversão do Aulacógeno do Paramirim, no qual predominam zonas de cisalhamento reversas-reversas destrais e vários tipos de dobras. Essas estruturas refletem um campo de tensão segundo WSW-ENE, os quais se desenvolvem nas unidades de embasamento do Aulacógeno, assim como na Suíte Intrusiva Lagoa Real, de idade estateriana, nos supergrupos Espinhaço e São Francisco, de idades estateriana-toniana e criogeniana, respectivamente, bem como no grupo Macaúbas-Santo

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Section: Regional Geological Contextmentioning

confidence: 99%

Tectonic inversion of compressional structures in the Southern portion of the Paramirim Corridor, Bahia, Brazil

et al. 2015

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“…Lagoa Real (ca. 1.7 Ga, Turpin et al 1988, Cordani et al 1992, Lobato et al 2015 and Borrachudos (1.7 Ga, Dossin et al 1993) granitoids represents the associated plutonism. The Statherian magmatic rocks located in the Bahia State mentioned above are the most probable sources for the Late Paleoproterozoic zircons.…”

Section: Possible Source Areasmentioning

confidence: 99%

Stratigraphy, tectonics and detrital zircon U-Pb (LA-ICP-MS) geochronology of the Rio Preto Belt and northern Paramirim corridor, NE, Brazil

et al. 2017

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Two important Proterozoic metasedimentary sequences, the Rio Preto and Santo Onofre Groups, crop out along the northwestern margin of the São Francisco craton and in northern Paramirim corridor, respectively. The Rio Preto Group, involved in the eponymous fold-thrust belt along the northwestern cratonic boundary, comprises the Formosa (garnet schist, quartz-mica schist, quartzite, chlorite-sericite schist and ferriferous quartz schist) and Canabravinha (quartzite, micaceous quartzite, metarhytmite, phylite, schist and metaturbidite) formations. The Santo Onofre Group occurs exclusively in the Paramirim corridor, and is composed of quartzite and minor carbonaceous or Mn-rich phylite. These units record sedimentation in shallow to deep-water marine settings related to rift basins, and were deformed and metamorphosed under greenschist facies conditions during the Brasiliano orogeny. Here we present 427 new detrital zircon U-Pb ages, which constrain the maximum depositional ages of ca. 971 Ma for the Santo Onofre Group, ca. 912 Ma for the Canabravinha Formation, and ca. 965 Ma for the Formosa Formation of the Rio Preto Group. Our data suggests that the Santo Onofre and the Rio Preto Groups accumulated in two distinct basin settings. The latter, composed mostly of sandy rocks, would represent a relatively stable, shallow-marine shelf environment. The Rio Preto Group, with metadiamictite, quartzite, pelitic and rhythmitic rocks, represents a shallow to deep marine environment influenced by gravity flows. Both groups were probably deposited in the Late Tonian, and are potential correlatives of the lower (pre-glacial) units of the Macaú-bas Group of the Araçuaí belt. KEYWORDS:Detrital zircon U-Pb geochronology, Brasiliano orogeny, sedimentary provenance, Rio Preto Belt, Paramirim corridor. RESUMO: Duas importantes sequências metassedimentares proterozoicas ocorrem ao longo da margem noroeste do Cráton do

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“…Uranium mineralization at Lagoa Real is found as finely disseminated (micro-to milimeter size) uraninite associated with discontinuous tabular bodies of albitites located along shear zones [1,4,7,9,13,22]. Most bodies trend N40E to N30W and dip 30°to 90°to the southwest or northwest, with the exception of the northernmost deposits, which dip to the east, and those situated in the central part of the region, which are almost vertical.…”

Section: Figure 1 Geological Map Of the Lagoa Real Uraniferous Albitmentioning

confidence: 99%

“…The Lagoa Real Uraniferous Province and its surroundings have been the subject of * E-mail: alex2010@ufmg.br geological and aerogeophysical surveys [1][2][3] and of various studies of the origin and control of uranium deposits, including those of [4][5][6][7][8][9][10][11][12]. Some of these studies disagree about the age of the Lagoa Real uraniferous mineralization, but usually its genesis is attributed to uranium and sodium-bearing hydrothermal fluids, which metasomatised the 1.75 Ga anorogenic Săo Timóteo granite (granite age by [7,10,13]) to yield U-rich albitites. [14] show?…”

Section: Introductionmentioning

confidence: 99%

New geological model of the Lagoa Real uraniferous albitites from Bahia (Brazil)

Chaves

2013

Open Geosciences

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New evidence supported by petrography (including mineral chemistry), lithogeochemistry, U-Pb geochronology by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), and physicochemical study of fluid and melt inclusions by LA-ICP-MS and microthermometry, point to an orogenic setting of Lagoa Real (BahiaBrazil) involving uraniferous mineralization . Unlike the previous models in which uraniferous albitites represent Na-metasomatised 1.75 Ga anorogenic granitic rocks, it is understood here that they correspond to metamorphosed sodium-rich and quartz-free 1.9 Ga late-orogenic syenitic rocks (Na-metasyenites). These syenitic rocks are rich not only in albite, but also in U-rich titanite (source of uranium). The interpretation of geochemical data points to a petrogenetic connection between alkali-diorite (local amphibolite protolith) and sodic syenite by fractional crystallization through a transalkaline series. This magmatic differentiation occurred either before or during shear processes, which in turn led to albitite and amphibolite formation. The metamorphic reactions, which include intense recrystallization of magmatic minerals, led uraninite to precipitate at 1.87 Ga under Oxidation/Reduction control. A second population of uraninites was also generated by the reactivation of shear zones during the 0.6 Ga Brasiliano Orogeny. The geotectonic implications include the importance of the Orosirian event in the Paramirim Block during paleoproterozoic Sȃo Francisco Craton edification and the influence of the Brasiliano event in the Paramirim Block during the West-Gondwana assembly processes. The regional microcline-gneiss, whose protolith is a 2.0 Ga syn-collisional potassic granite, represents the albitite host rock. The microcilne-gneiss has no petrogenetic association to the syenite (albitite protolith) in magmatic evolutionary terms. Keywords

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U-Pb, Rb-Sr and Sm-Nd chronology of granitic basement, hydrothermal albitites and uranium mineralization (Lagoa Real, South-Bahia, Brazil)

Cited by 104 publications

References 22 publications

Tectonic inversion of compressional structures in the Southern portion of the Paramirim Corridor, Bahia, Brazil

Tectonic inversion of compressional structures in the Southern portion of the Paramirim Corridor, Bahia, Brazil

Stratigraphy, tectonics and detrital zircon U-Pb (LA-ICP-MS) geochronology of the Rio Preto Belt and northern Paramirim corridor, NE, Brazil

New geological model of the Lagoa Real uraniferous albitites from Bahia (Brazil)

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