The Serra do Caparaó Complex, Mantiqueira Province, Brazil, revisited: metamorphic age constraints by U-Pb and Lu-Hf method in zircon by LA-ICP-MS

Abstract

The U-Pb method was used in order to understand the high-grade metamorphic rocks in the Ribeira Belt (SE Brazil) and Lu-Hf isotopes were applied to investigate the magmatic photolith sources and the tectonic setting of Serra do Caparaó Complex rocks. The results indicate the existence of two thermal events: the first related to a Paleoproterozoic magmatic event and the second one linked to high-grade metamorphism related to the Brasiliano Orogeny. The U-Pb age interval from 2209 to 2060 Ma obtained in zircon grains from the granulitic orthogneiss with TDMcrustal ages ranging from 2.13 to 3.87 Ga may be interpreted as mantle-derived source with important older crust participation in the magma formation; juvenile arc-related rocks were generated at this time as indicated by the positive ƐHf values. The second group of U-Pb ages ranging from 633 to 584 Ma is interpreted as a metamorphic event, resulting from the collisional process related to the Gondwana assembly.

A Juvenile Component in the Pre- and Post-Collisional Magmatism in the Transition Zone between the Araçuaí and Ribeira Orogens (SE Brazil)

“…The SAIC's isotopic signature suggests that at least three magmatic sources were present, namely: a mantle source with positive εHf values; a crustal source with negative εHf values and Meso to Neoproterozoic model ages; and a crustal source with highly negative εHf values and Paleoproterozoic and Archean model ages. The crustal source that presents Paleoproterozoic and Archean model ages has similarities with the signatures of the Caparaó suite, which was associated with the Juiz de Fora Complex (Figure 13) [62,64]. The crustal source that presents Meso to Neoproterozoic model ages has affinities with the isotopic signatures found in the paraderived rocks of the Bom Jesus do Itabapoana Group, the Nova Venécia Complex, and the Rio Doce magmatic arc (Figure 13) [41,44].…”

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

“…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.…”

“…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.…”