U-Pb evidence for late Neoarchean crustal reworking in the Southern São Francisco Craton (Minas Gerais, Brazil)

Abstract

The Passa Tempo Metamorphic Complex is one of several metamorphic complexes that form the Archean sialic crust of the southern São Francisco Craton. It encompasses hypersthene-bearing gneissic rocks, with subordinate NW-or EW-trending mafic-ultramafic bodies and granodioritic to alkali-granitic, weakly foliated, and light-colored granitoids. These granitoids are the product of generalized migmatization that followed granulite-facies metamorphism. To determine the ages of the granulite-facies metamorphism and granitoid genesis, we obtained U-Pb ages on zircon extracted from the mesosome and leucosome of the migmatitic gneisses. For the mesosome, a discordia that intercepts Concordia at 2622 ± 18 Ma is interpreted as a minimum age for granulite-facies metamorphism. For the leucosome, the upper intercept of discordia at 2599 ± 45 Ma corresponds to migmatization and granitoid genesis. Contemporaneous metamorphism and magmatism have been documented elsewhere in the São Francisco Craton, especially in the southern portion, demonstrating vast and vigorous reworking of sialic crust by the end of the Neoarchean.

Shrimp U–Pb zircon age evidence for Paleoproterozoic sedimentation and 2.05Ga syntectonic plutonism in the Nyong Group, South-Western Cameroon: consequences for the Eburnean–Transamazonian belt of NE Brazil and Central Africa

“…The present study has clarified this question by showing that ages in this range correspond to growth/overgrowth of zircon during a metamorphic/thermal event at 2500 Ma. Such an event may correspond to a late Neoarchean plutonism and intensive crustal reworking such as reported in the São Francisco and Congo cratons (Nsifa and Riou, 1990;Campos et al, 2003;Oliveira et al, 2004).…”

“…Data from(Korsin et al, 2003;Oliveira et al, 2004;Campos et al, 2003;Barbosa and Sabaté, 2002;Tchameni et al, 2000;Shang et al, 2004;Toteu et al, 1994;Caen-Vachette et al, 1988).…”

Litogeoquímica do Complexo Campos Gerais e granitoides intrusivos, Arqueano/Paleoproterozoico, Brasil

“…O antepaís relacionado à orogenia paleoproterozoica é composto por complexos metamórficos, exibindo terrenos ortognáissicos do tipo TTG, granitoides e sequências vulcanossedimentares arqueanas (3,0 a 2,8 Ga), retrabalhados por eventos metamórficos entre 2,7 e 2,6 Ga (Noce, Machado, Teixeira 1998, Campos, Carneiro, Basei 2003.…”

“…No Complexo Passa Tempo, a sudoeste do Complexo Belo Horizonte, datações U-Pb em migmatitos forneceram idades de 2,6 Ga para o metamorfismo, migmatização e granitogênese (Campos, Carneiro, Basei 2003).…”

Neoarchean and Paleoproterozoic granitoids marginal to the Jeceaba-Bom Sucesso lineament (SE border of the southern São Francisco craton): Genesis and tectonic evolution

“…Along this structure, elongated bodies of Paleoproterozoic metasedimentary rocks and subordinately metaultramafic rock lenses of unknown age occur (Campos, 2004). The terrane situated NW of JBSL is a Mesoarchean crustal domain of polycyclic evolution that was affected by Neoarchean granitoid magmatism Endo, 1997;Campos et al, 2003;Campos, 2004). The terrane situated SE of JBSL evolved essentially in the Paleoproterozoic Campos, 2004).…”