2.17–2.10 Ga plutonic episodes in the Mineiro belt, São Francisco Craton, Brazil: U-Pb ages, geochemical constraints and tectonics

• Petrogenesis and tectonic setting of Paleoproterozoic plutonic rocks.
• Zircon Hf, U-Pb ages, Nd-Sr constraints and geochemistry.
• Plutonic episodes (2.17–2.10 Ga) akin to continental arc setting.
• Final accretion of the Mineiro belt onto an Archean landmass.

Geologic information supported by in situ U-Pb zircon ages, and geochemistry coupled with zircon Hf and Nd-Sr isotopic analyses on orthogneisses, metagranitoids and metadiorites unravel the nature and tectonic significance of a calc-alkaline continental arc in the Mineiro belt – southern portion of the São Francisco Craton. The zircon U-Pb ages defined two plutonic episodes: 2174–2149 Ma (metaquartz-diorite, metagranitoids and orthogneisses) and 2145–2100 Ma (metadiorites, metagranitoids and orthogneisses) whereas several samples contain inherited zircons with concordant 207Pb/206Pb ages as old as 2785 Ma. Our rocks show variable SiO2 contents (54.8–77.1 wt.%), are metaluminous to peraluminous and mostly magnesian and variably enriched in LREE. The older rocks have La/YbN = 2.24 to 11.87 whereas the metadiorites have La/YbN = 9.60–13.82 and the youngest rocks in the range 7.79–91.27. Most samples show Nb and Ti negative anomalies that can be attributed to a subducted source whereas some yield marked Pb positive anomalies that highlight the important role of crustal contamination/assimilation. Dy/Dy* and coupled Dy/Yb values (from 0.7 to 0.5 and 1.4 to 2.0, respectively) indicate the metaigneous rocks derived from a LREE enriched MORB source in a subduction zone with mixed Paleoproterozoic and Archean material. This scenario is consistent with the U/Pb data from inherited nuclei and xenocrysts, the range of the zircon ɛHf(t) (from +8 to −10) and ɛNd(t) (from −7 to +0.3) values, as well as with the Lu-Hf TDM ages that vary between 2.3 and 3.2 Ga. Our data and regional geologic–tectonic correlations are consistent with the onset of an ultimate collisional event in the Mineiro belt that followed a long-lived accretionary regime active in Proterozoic times, outboard the Archean core of the São Francisco Craton.