A review of 3.66 to 2.77 Ga crustal differentiation in the northern São Francisco Craton, Brazil

The Archaean crustal evolution of the northern São Francisco Craton (SFC) reveals significant similarity with Kaapvaal-Zimbabwe and Pilbara, cratons, especially before 3.0 Ga. Likewise, compiled geochronological and Nd-Sr-Hf isotope data suggest that the Archaean blocks of the northern part of SFC (e.g. Gavião, Uauá and Serrinha) shared similar crustal evolution since 3.15 Ga. The 3.42–3.35 Ga TTGs of the southern and western Gavião Block have negative and slightly positive ɛ_Nd(t) and ɛ_Hf(t) values and T_DM(Hf) ages between 3.50 and 3.90 Ga, indicating that they were produced by partial melting of Eoarchaean to Palaeoarchaean crust, with minor mantle sources. The ca. 3.30 Ga high-silica plutonic-volcanic system, which is related to intraplate magmatism and intracrustal differentiation processes, would represent processes of continental rifting and break-up. In the northern Gavião Block, the 3.64 Ga migmatite-gneiss paleosomes with negative ɛ_Hf(t), ¹⁷⁶Hf/¹⁷⁷Hf ratio between 0.2802 and 0.2805 and T_DM(Hf) ages between 3.75 and 4.15 Ga of the Mairi Complex represent the oldest dated rocks of the whole São Francisco Craton, suggesting late Hadean and Eoarchaean sources. The 3.15 and 3.00 Ga rocks of the Serrinha Block have positive ɛ_Nd(t) values, suggesting a predominant juvenile source. Likewise, coeval 3.15 and 3.00 Ga Uauá Block rock assemblage has slightly positive to negative ɛ_Nd(t) values, which indicate mixing of crustal and juvenile sources. The 2.90 to 2.77 Ga period in the SFC is characterized by pervasive crustal anatexis with high-K granite generation, similar to Kaapvaal and Pilbara cratons. Therefore, Archaean migmatite-gneiss terrains recorded four crustal differentiation intervals (e.g. 3.66–3.51, 3.45–3.30, 3.15–3.00 and 2.90–2.77 Ga) in the São Francisco Craton.