Pseudosection modeling and U-Pb geochronology on Piranga schists: role of Brasiliano Orogeny in the Southeastern Quadrilátero Ferrífero, Minas Gerais, Brazil

Queiroz, Yanne da Silva; Queiroga, Gláucia Nascimento; Moraes, Renato; Fernandes, Victor Matheus Tavares; Medeiros‐Junior, Edgar; Jordt-Evangelista, Hanna; Schulz, Bernhard; Schmiedel, Julia; Martins, Maximiliano; Castro, Marco Paulo de; Lana, Cristiano

doi:10.1590/2317-4889201920180136

Cited by 2 publications

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References 80 publications

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“…The QF is located in the Southeastern edge of the São Francisco Craton (SFC), bordering the Araçuaí orogen (Fig. 1A), (Almeida 1977, Alkmim and Marshak 1998, Alkmim and Martins-Neto 2012, Queiroz et al 2019. The QF was affected by two superimposed orogens: • Paleoproterozoic Minas orogeny (2100( -1900Teixeira et al 2015), also known as Transamazonian orogeny (Alkmim and Marshak 1998), which resulted from the collisional events between the cores of both Congo and São Francisco cratons (Fig.…”

Section: Geological Settingmentioning

confidence: 99%

Depositional setting and U-Pb detrital record of rift-related deposits in the Moeda Formation (Minas Supergroup) at the Gandarela and Ouro Fino synclines, Quadrilátero Ferrífero, Brazil

et al. 2021

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The Moeda Formation (Caraça Group, base of Minas Supergroup) registers the initial rift stages of the Minas Basin in the Quadrilátero Ferrífero, Southern São Francisco craton, SE-Brazil. We present stratigraphic and U-Pb detrital zircon dating analyses of the Moeda Formation that contribute to the comprehension of its sedimentary evolution in the southernmost Gandarela and Ouro Fino synclines (Central-Eastern Quadrilátero Ferrifero). The Moeda Formation sequence consists of a basal proximal alluvial fan with clast-supported conglomerates, grading upward into an alluvial floodplain with quartz arenites, and upper massive sandstones from distal fluvial fans. Because the Moeda Formation is normally limited by similar lithologies at both its base (Nova Lima Group, Rio das Velhas Supergroup) and top (Batatal Formation, uppermost Caraça Group) and stratigraphic inversion has occurred in the study area, U-Pb detrital zircon dating was also extended to these units to differentiate them stratigraphically. The youngest clusters of detrital zircon ages in the Nova Lima Group and Moeda and Batatal formations were 2716, 2777 and 2786 Ma, respectively. Based on our data and relevant literature, the depositional age of the Moeda Formation was interpreted as between 2716 and 2520 Ma with the Mesoarchean continental crust, the Rio das Velhas Supergroup and the Archean TTG complexes as its main source areas.

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Section: Geological Settingmentioning

confidence: 99%

Depositional setting and U-Pb detrital record of rift-related deposits in the Moeda Formation (Minas Supergroup) at the Gandarela and Ouro Fino synclines, Quadrilátero Ferrífero, Brazil

et al. 2021

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Fluid flow and syntectonic veining in an Ediacaran-Cambrian foreland fold–thrust zone, western margin of the São Francisco Craton, Brazil

Esteves

Faleiros

2021

JGS

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The western margin of the São Francisco Craton, central Brazil presents a 1300 km-long foreland fold-thrust belt where Ediacaran (560–520 Ma) metasedimentary rocks from the Bambuí Group were subsequently deformed during post-collisional stages (520–495 Ma) related to Gondwana assembly. This scenario provides an opportunity to quantify fluid flow regimes and fault-related processes that were active in exhumed foreland fold-thrust zones, which were estimated based on structural, microstructural, and fluid inclusion studies of syntectonic veins and host rocks. Kaolinite-bearing synkinematic mineral assemblages from metasedimentary rocks, thermodynamic models and grain-scale deformation accommodated by dissolution-precipitation creep and intracrystalline deformation indicate metamorphic and deformational conditions of 250–270°C. Subhorizontal extensional veins formed under subhorizontal shortening and subvertical extension, supporting vein development under a fold-thrust regime that formed regional NW-trending thrust fault zones and megafolds with NW-trending axes. Orientation and growth microstructures indicate that NW-trending subvertical cleavage-parallel veins formed under subhorizontal NE-SW extension, compatible with those inferred to produce mapped kilometric-scale, gentle folds with NE-trending traces. Two primary aqueous fluid inclusion assemblages (FIA) are distinguished by salinity variation: 2-21 wt.% NaCleq. in subhorizontal veins and 6–0 wt.% NaCleq. in cleavage-parallel subvertical veins. Fluid inclusion thermometry and microstructural analysis suggest that veins crystallized between 250–270 °C under fluid pressure fluctuating within 50–500 MPa (subhorizontal veins) and 80–320 MPa (cleavage-parallel subvertical veins), evidencing fault-valve behavior. Trends of coupled decreases in salinity and homogenization temperatures in both FIA indicate downward mixing of meteoric fluids, which was more effective in subvertical veins, and in both cases enhanced by fault-valve behavior. Dominance of moderate-salinity and absence of CO2 and CH4 indicate the fluids are dominated by formation waters. The salinity signature is similar to those of formation waters and metamorphic fluids derived from rocks of shallow marine environments worldwide.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5275031

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Pseudosection modeling and U-Pb geochronology on Piranga schists: role of Brasiliano Orogeny in the Southeastern Quadrilátero Ferrífero, Minas Gerais, Brazil

Cited by 2 publications

References 80 publications

Depositional setting and U-Pb detrital record of rift-related deposits in the Moeda Formation (Minas Supergroup) at the Gandarela and Ouro Fino synclines, Quadrilátero Ferrífero, Brazil

Depositional setting and U-Pb detrital record of rift-related deposits in the Moeda Formation (Minas Supergroup) at the Gandarela and Ouro Fino synclines, Quadrilátero Ferrífero, Brazil

Fluid flow and syntectonic veining in an Ediacaran-Cambrian foreland fold–thrust zone, western margin of the São Francisco Craton, Brazil

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