Here, we report on the first radiometric dating of pre-Quaternary sinters covering the ENE–WSW striking vertical faults filled with Upper Badenian sands (neptunian dykes) in Mesozoic carbonates of the Devín quarry in the Malé Karpaty Mountains. The ²³⁸U/²⁰⁶Pb age of 13.98±0.56 Ma fits well with the former age prediction based on biostratigraphic evidence. Our results provide fault opening age, refine the age of sediments and fossils preserved in the neptunian dykes, and constrain the onset of Badenian sea transgression.