Ophiolitic metamafic remnants of Palaeoproterozoic oceanic crust from the Cláudio shear zone, Southern São Francisco Craton (Brazil)

Early evidence of plate tectonics as a global phenomenon can be provided by Palaeoproterozoic ophiolites. Metamafic rocks preserved within the Southern São Francisco Craton (Brazil) along the Cláudio shear zone (suture zone) are regarded as part of the dismembered Cláudio meta-ophiolite. Here, we investigate the petrology and tectono-magmatic setting of these metamafites using petrography, whole-rock geochemistry, and mineral chemistry. Geochronological data and geodynamic implications were explored using Sm-Nd and U-Pb methods. We found that their protoliths (gabbro and basalt) are tholeiitic and sub-alkaline with an E-MORB signature, suggesting that they were remnants of oceanic crust. Metagabbro preserves igneous relics and prograde assemblages from very low- to medium-grade metamorphism. Metabasalts showed an assemblage of amphibolite facies. The 2276 Ma whole-rock Sm-Nd TDM model age and the 2050 Ma U-Pb age of metamorphic zircons indicate a Palaeoproterozoic evolution of the palaeo-oceanic basin. It was closed owing to NW-dipping subduction, followed by continental collision involving the Divinópolis and Campo Belo/Bonfim metamorphic complexes. Our results support previous studies that suggest a possible connection between São Francisco-Congo and North China/Yangtze cratons during the formation of the Columbia (Nuna) supercontinent. Furthermore, this study provides additional evidence supporting that modern-style plate tectonics operated during the Palaeoproterozoic.