The peraluminous Aurumina Granite Suite in central Brazil: An example of mantle-continental crust interaction in a Paleoproterozoic cordilleran hinterland setting?

Peraluminous granites and tonalites/granodiorites of the Aurumina Suite crop out in the external zone of the Brasília Fold Belt on the western margin of the São Francisco Craton. Rocks of this suite intrude retrograde medium-grade schists and paragneisses of the Ticunzal Formation and display a magmatic muscovite ± biotite ± garnet assemblage and discrete graphite lamellae. The suite is divided into six members (Au1 through Au6), which grade from synkinematic to post-kinematic in character with ages spanning from 2.11 to 2.16 Ga according to zircon U-Pb data. Compositional features of the Aurumina Suite and associated coeval metaluminous mafic to intermediate plutons suggest an origin by source hybridization processes characterized by reaction between metasedimentary rocks and basaltic melts that would have taken place at shallow depths (pressure < 5 kbar). This is supported by a narrow range of εNdT values between −4.2 and +0.4 for samples from both peraluminous and metaluminous units. Possible sources could correspond to old reworked crust that might also be related to the origin of ∼2.2 Ga peraluminous magmatic rocks in the Almas-Dianópolis domain, although participation of unknown sources is also feasible. Similarities exist between the peraluminous magmatism of the Aurumina Suite and the Jurassic-Paleogene peraluminous granitic belt of the cordilleran interior of North America in terms of composition, rock association and tectonometamorphic context, which suggest a similar tectonic setting for the Aurumina Suite instead of the collisional setting suggested in previous works.