Eoarchean to Neoproterozoic crustal evolution of the Mantiqueira and the Juiz de Fora Complexes, SE Brazil: Petrology, geochemistry, zircon U-Pb geochronology and Lu-Hf isotopes

Abstract

The Mantiqueira and the Juiz de Fora Complexes (MQC and JFC) in the Araçuaí-Ribeira orogenic system, southeastern Brazil, have been regarded as parts of the Neoproterozoic to Cambrian Brasiliano Orogeny formed by a series of collisions of the São Francisco and the Congo Cratons. Here we report new petrological, geochemical, and zircon U-Pb and Lu-Hf isotopic data on felsic to mafic orthogneisses from the complexes with a view to evaluate the timing and P-T conditions of the collisional event as well as protolith formation. Metamorphic P-T estimates for orthogneisses indicate amphibolite-facies conditions of 650–730 °C and 5.8–9.1 kbar from the MQC, whereas slightly higher (upper amphibolite- to lower granulite-facies) conditions of 680–770 °C and 6.0–7.7 kbar were obtained from the JFC. Geochemical, zircon U-Pb geochronological, and Lu-Hf isotopic data of felsic orthogneisses indicate that the MQC was formed by a series of Neoarchean (ca. 2.67 and 2.61 Ga) volcanic arc magmatisms with magma sourced from Eoarchean to Paleoarchean (ca. 3.82–3.42 Ga) crustal components. In contrast, slightly younger U-Pb ages of ca. 2380 Ma and ca. 2050–1960 Ma were obtained from the JFC marking the timing of volcanic arc magmatism as Early to Middle Paleoproterozoic, with magma sourced from Paleoarchean (∼3.45 Ga) crust with addition of juvenile crustal components. The recycled ancient crustal components were also supplied for late Neoproterozoic (ca. 600 Ma) continental arc magmatism of the JFC. The high-grade metamorphism is possibly related to the final collision of the Congo and São Francisco Cratons at 590–560 Ma, which broadly compares with the formation of the Kuunga Orogen.