U–Pb ages via LA-ICP-MS of carbonate from brittle structures of Jandaíra formation, Potiguar basin, NE-Brazil

Abstract

U–Pb carbonate dating by LA-ICP-MS is becoming a popular tool to investigate the timing of brittle deformation. In northeast Brazil, the absolute dating of brittle deformation in a series of rift-related intracontinental basins associated with the South Atlantic Rift has been little explored. Here we add on that, by investigating carbonate infilling and dating of fractures/veins from the Jandaíra limestone, part of the post-rift sequence of the Potiguar Basin. Until now, these features' ages (Lower Cretaceous to Middle Miocene) were inferred by field relationship and stratigraphic studies. Carbonates that were previously considered impossible to date, have been dated using a recent and challenging technique of U–Pb dating via LA-ICP-MS. Our data, the first ones with this method on this basin, indicate that post-rift brittle deformation can be constrained between 45 and 30 Ma. This interval is coincident with a major magmatic event (Macau-Messejana) suggesting a causal relationship between magmatism and brittle deformation, but the origin of the stress associated with this tectono-magmatic remains debatable. We validate here the use of U–Pb carbonate dating and its application for dating brittle deformation in northeast Brazil rift-related basins.