Zircon U–Pb ages and Hf isotope compositions of Açucena Granite (Borrachudos Suite): Implications for Statherian-Cambrian tectono-magmatic evolution of the southern border of the São Francisco Craton, Brazil

Gomes, Sylvio Dutra; Silva, Rosaline Cristina Figueiredo e; Kemp, Anthony I.S.; Santos, João Orestes Schneider; Hagemann, Steffen; Lobato, Lydia Maria; Rosière, Carlos Alberto; Novo, Tiago Amâncio

doi:10.1016/j.jsames.2020.102543

Cited by 12 publications

(2 citation statements)

References 63 publications

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“…8B) is associated with the late-and post-collisional phases (560 -~530 Ma). Hot hydrothermal fluids from anatectic pegmatites promoted quartz leaching and crystallization of magnetite (Kmag) crystallization leading to irregular orebodies of oxides with granoblastic fabric as seen in the Horto-Baratinha deposit (Gomes et al, 2018(Gomes et al, , 2020Silveira Braga et al, 2020;Silveira Braga, Rosière, Santos, Hagemann, McNaughton, et al, 2019). In this deposit the magnetite grains from high-grade ore bodies (0.5 to 0.7‰) exhibit an enrichment of Mg, V, Cr, Mn, Co, Ni, Zn, and Ga compared to the hematite from IFhosted rock (Silveira Braga et al, 2021) and the δ 18 O mineral values of magnetite are heavier than the usual iron formation-hosted deposits worldwide (fig.…”

Section: From Iron Formation To Ore -The Evolution Of the δ 18 O Sign...mentioning

confidence: 99%

Oxygen Isotopes of Iron Oxides as a Diagnostic Tool for Iron Formation-Hosted High-Grade Magnetite-Hematite Deposits

Silveira Braga,

Rosière,

Pack

et al. 2023

American Journal of Science

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Coarse-grained granoblastic magnetite-hematite and sheared platy hematite iron orebodies comprise several small deposits (5 to 30 Mt each) on the eastern margin of the São Francisco Craton, bordering the Ediacaran–Cambrian Brasiliano Orogenic belt. Three main mineralization stages are associated with the Brasiliano Orogeny: (1) syn- to the late-collisional stage (ca. 580–560 Ma) with development of lens-shaped schistose orebodies along thrust planes. (2) late- to the post-collisional stage (ca. 560–530 Ma) with the formation of massive magnetite bodies by contact metamorphic-metasomatism with pegmatite. (3) Post-tectonic stage with crystallization of granular hematite associated with late pegmatite (ca. 530–490 Ma). In order to better evaluate the fluid oxygen signature of each mineralization stage, new oxygen isotopes measurements were performed on ore bodies associated with the three stages. These stages are followed by changes in the oxygen isotope signature, with a progressive decrease of the δ18O from the iron formation (1.7 to 8.1‰) to high-grade ore (-1.6 to 2.6‰) that appears to be a common aspect of the mineralization of iron formations. In the present cases, magmatic fluids (δ18O from 4.6 to 13.1‰) have imprinted a relatively “heavier” signature than the most hypogene iron formation high-grade ores worldwide that was progressively modified by meteoric water percolated along extensional fractures. The iron oxides from the contact zones of pegmatitic yielded intermediate δ18O values (1.8 to 5.0‰), indicating a higher magmatic fluid/rock ratio.

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Section: From Iron Formation To Ore -The Evolution Of the δ 18 O Sign...mentioning

confidence: 99%

Oxygen Isotopes of Iron Oxides as a Diagnostic Tool for Iron Formation-Hosted High-Grade Magnetite-Hematite Deposits

Silveira Braga,

Rosière,

Pack

et al. 2023

American Journal of Science

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“…Crystallization was dated between 1.75 and 1.69 Ga (Brito-Neves et al, 1979;Machado et al, 1989; HENRIQUE C. JONCEW -2024 Fernandes, 2001;Gomes et al, 2020), an age considered to be the maximum, for the Espinhaço system. A hematitic phyllite, first described by Moraes and Guimarães (1930), dated at ca.…”

Section: Statherian and Calymmian Riftings The Serra De São José Grou...mentioning

confidence: 99%

Tectonic evolution of the Southern Espinhaço Front in Serra do Cipó-MG

Joncew

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Implications of the dominant LP–HT deformation in the Guanhães Block for the Araçuaí West-Congo Orogen evolution

et al. 2022

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Zircon U–Pb ages and Hf isotope compositions of Açucena Granite (Borrachudos Suite): Implications for Statherian-Cambrian tectono-magmatic evolution of the southern border of the São Francisco Craton, Brazil

Cited by 12 publications

References 63 publications

Oxygen Isotopes of Iron Oxides as a Diagnostic Tool for Iron Formation-Hosted High-Grade Magnetite-Hematite Deposits

Oxygen Isotopes of Iron Oxides as a Diagnostic Tool for Iron Formation-Hosted High-Grade Magnetite-Hematite Deposits

Tectonic evolution of the Southern Espinhaço Front in Serra do Cipó-MG

Implications of the dominant LP–HT deformation in the Guanhães Block for the Araçuaí West-Congo Orogen evolution

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