Detrital zircon U-Pb ages as evidence for deposition of the Saúde Complex in a Paleoproterozoic foreland basin, northern S~ao Francisco Craton, Brazil.

Abstract

The Archean and Paleoproterozoic terrane of the northeastern part of the S~ao Francisco Craton shows evidence of a prolonged accretionary history. A major boundary within this portion of the craton is the Contendas-Jacobina lineament, a 600 km-long north-trending left-lateral thrust fault that separates major Archean blocks amalgamated during the Paleoproterozoic orogeny. Different supracrustal sequences occur along this lineament, but the tectonic imbrication erased the original stratigraphy, precluding the reconstruction of the sedimentary and tectonic evolution of the different groups. We investigated the sediment provenance and tectonic setting of the Saúde Complex, located in the northern part of the Contendas-Jacobina lineament and previously taken as part of the Bahia Gold Belt. We found that the Saúde Complex is part of a Paleoproterozoic foreland basin and correlates with the Contendas- Mirante Basin in the south. The correlation with the western Au-bearing Jacobina Basin as a single Paleoproterozoic basin is no longer favorable. The Saúde Complex contains abundant 2.06e2.20 Ga and 2.50e2.68 Ga detrital zircons mainly derived from the eastern Itabuna-Salvador-Curaç a Orogen and reworked Neoarchean rocks within the orogen, mainly the Caraíba magmatic arc.