Calymmian (1.50-1.45 Ga) magmatic records in Votuverava and Perau sequences, south-southeastern Brazil: Zircon ages and Nd-Sr isotopic geochemistry

The main aim of this work is to present and discuss the U-Pb zircon ages and Nd-Sr isotopic data from the metabasic rocks that occur within the metamorphosed Votuverava and Perau volcano sedimentary sequences, located in the Apiaí Terrane, south-southeastern Brazil. The geochemical pattern of most of these metabasic rocks is similar to those of tholeiitic basalts, suggesting an extensional environment. The U-Pb zircon ages obtained around ca. 1480 Ma characterize an important basic magmatism during the Mesoproterozoic in south-southeastern Brazil. Nd model ages and e{open} _Nd/e{open} _Sr signatures suggest the Mesoproterozoic as the main period of mantle/crust differentiation for the crustal precursors of these metabasic rocks. It is quite possible that the Mesoproterozoic extentional events that caused the opening of large sedimentary basins in southern-southeastern Brazil have been underestimated. Possible regional correlations between the Votuverava-Perau basin (PR), the Betara and água Clara sequences (PR-SP) and the Serra do Itaberaba Group (SP) demonstrate the magnitude of the extensional process associated with the break-up of the preexisting continental masses.