Siderian to Rhyacian evolution of the Juiz de Fora Complex: Arc fingerprints and correlations within the Minas-Bahia Orogen and the Western Central Africa Belt

Rhyacian magmatic arc rocks with sanukitoid geochemical signature from the Juiz de Fora Complex, Minas-Bahia Orogenic System (SE-Brazil)

“…The JFC sanukitoid rocks are quite similar to the other sanukitoid rocks of the southern São Francisco Paleocontinent and, in general, all suites have similar characteristics (fractionation between LREE and HREE; absent, slightly positive, or slightly negative Eu anomalies; enrichment in LILE and depletion in HFSE). However, for the JFC sanukitoid rocks, those described in this work and in Araújo et al (2021) are noticeably more enriched in LREE than those described by Almeida et al (2022), where the fractionation between LREE and HREE is less expressive. This implies that these rocks were generated by lower degrees of partial melting or fractionation processes than the others.…”

“…The JFC orthogranulites protoliths comprise magmatic arc calc-alkaline granitoid rocks, TTG, and sanukitoid suites, associated with mafic rocks of different geochemical signatures (mid-oceanic ridge basalt [MORB], island arc tholeiite [IAT], and post-collision alkaline basalts) with crystallization ages ranging from 2.40 to 1.90 Ga (Table 1; Heilbron et al 1998, Silva et al 2002, André et al 2009, Degler et al 2018, Araújo et al 2019, Kuribara et al 2019, Almeida et al 2022, Faria et al 2022. While previous works have interpreted the JFC as an initially juvenile intraoceanic magmatic arc that evolved into a more mature one (Duarte et al 1997, Heilbron et al 1998, Araújo et al 2019, recent works have shown some evidence of reworking of some older Mesoarchean crust within this complex (Araújo et al 2021, Almeida et al 2022. The JFC represents the last magmatic arc to be accreted onto the southern margin of the São Francisco Paleocontinent, having collided with the Mantiqueira Complex during the early Orosirian (between 2.03 and 2.02 Ga; Heilbron et al 1998, Noce et al 2007, Degler et al 2018, Araújo et al 2019, Bruno et al 2020, 2021a, 2021b, Almeida et al 2022.…”

“…Previous tectonic models for the evolution of the JFC suggest an early evolutionary stage with moderately juvenile tholeiitic magmatism at 2.44 Ga, followed by moderately juvenile to evolved TTG-sanukitoid magmatic pulses between 2.20-2.18 and 2.07 Ga, and moderately juvenile tholeiitic magmatic pulses at 2.13 Ga (Araújo et al 2019, Almeida et al 2022. The JFC rocks record two high-grade metamorphic events: one in the beginning of the Orosirian (~2.03-2.02 Ga), interpreted as resulting from the collision of the JFC with the Mantiqueira Complex during the terminal phases of the São Francisco Paleocontinent amalgamation (Araújo et al 2021), and another one in the Ediacaran (around 600-580 Ma), interpreted as the reworking of the continental margin by the Brasiliano/Pan-African orogenic system (Machado et al 1996, Heilbron et al 1998, 2020a, Kuribara et al 2019, Cutts et al 2020, Almeida et al 2022, Faria et al 2022.…”

“…7), the integration and analysis of these data suggest that the rocks from the Minas segment of the MBOS, in the southern São Francisco Paleocontinent, record at least two stages of sanukitoid generation: the first and more long-lived event, between 2.20 and 2.11 Ga, is coincident with the climax of juvenile crust formation within the Minas Segment of the MBOS and coeval with the generation of different sanukitoid suites (along with TTG suites and granitoid rocks) from the Mineiro Belt (Seixas et al 2013, Moreira et al 2018, Bruno et al 2021b) and the Mantiqueira and JFC complexes (Bruno et al 2020and this work); the second and younger event, dated at ca. 2.07 Ga, is restricted to the JFC (Almeida et al 2022) and was emplaced immediately before the regional metamorphism resulting from the diachronic collision of Archean blocks and Paleoproterozoic magmatic arcs during the final stages of São Francisco Paleocontinent amalgamation, as suggested by the emplacement of syn-collisional granitoid rocks and metamorphism ages between 2.05 Ga in Mineiro Belt (Moreira et al 2018, Bruno et al 2020, 2021b and 2.03 Ga in the JFC (Araújo et al 2021).…”