The Horto-Baratinha itabirite-hosted iron ore: A basal fragment of the Espinhaço basin in the eastern São Francisco Craton

Braga, Flávia Cristina Silveira; Rosière, Carlos Alberto; Santos, João Orestes Schneider; Hagemann, Steffen; McNaughton, Neal J.; Salles, Pedro Valle

doi:10.1016/j.jsames.2018.11.013

Cited by 17 publications

(7 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The layering is defined by the alternation of millimeter wide bands of quartz and iron oxides (fig. 3A, D, 4A-B), comprised of strongly oriented platy hematite crystals and subordinate granoblastic domains (Gomes et al, 2018;Silveira Braga et al, 2015;Silveira Braga, Rosière, Santos, Hagemann, McNaughton, et al, 2019). The grain size noticeably increases eastwards from sub-millimeter to millimeter.…”

Section: Geological Settingmentioning

confidence: 98%

“…The GB represents the deeper crustal roots of the Southern Espinhaço fold-thrust belt upthrusted on the thinskinned Espinhaço Supergroup during the Ediacaran-Cambrian Brasiliano orogeny. It comprises Archean TTG (tonalite-trondhjemite-granodiorite) terranes with magmatic U-Pb SHRIMP ages between 2867 ± 10 Ma to 2713± 7 Ma (L. C. da Silva et al, 2002), tectonic outliers of metamorphic Orosirian-Statherian iron formation-bearing supracrustal units (Carvalho et al, 2014;Rolim et al, 2016;Silveira Braga et al, 2015;Silveira Braga, Rosière, Santos, Hagemann, McNaughton, et al, 2019) and Statherian granitic plutons of the voluminous Borrachudos Suite (Magalhães et al, 2018;L. C. da Silva et al, 2002;Silveira Braga, Rosière, Santos, Hagemann, McNaughton, et al, 2019).…”

Section: Geological Settingmentioning

confidence: 99%

“…All units were intruded by post-tectonic Ediacaran-Ordovician pegmatite bodies in the period between 630 to 480 Ma (Gomes et al, 2018;Pedrosa-Soares et al, 2011;Silveira Braga, Rosière, Santos, Hagemann, McNaughton, et al, 2019;Silveira Braga et al, 2020).They comprise the Eastern Brazilian Pegmatite Province, one of the most significant pegmatite fields worldwide, subdivided into dis- tricts encompassing several pegmatite populations (fig. 1).…”

Section: Geological Settingmentioning

confidence: 99%

“…The iron formation is associated with quartzite, quartz micaschist, and para-amphibolite exposed by the mine works as a <40 m wide continuous layer between the upper and lower schists units. The strata are folded with the develop- ment of a dome and basin pattern (Silveira Braga, Rosière, Santos, Hagemann, McNaughton, et al, 2019). Pegmatite occurs as metric to several tens of meters-wide dikes and sills crosscutting the granites and metasedimentary rocks.…”

Section: Morro Escuro and Passabémmentioning

confidence: 99%

“…3I) which overprints and obliterates the structure of the IF. Accessory minerals such as ilmenite, quartz, carbonate, chlorite, amphiboles, biotite, talc, apatite, and muscovite are observed mainly at the contact with pegmatite intrusions Silveira Braga, Rosière, Santos, Hagemann, McNaughton, et al, 2019).…”

Section: Morro Escuro and Passabémmentioning

confidence: 99%

See 4 more Smart Citations

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

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Geological Settingmentioning

confidence: 98%