Dating the Late Miocene marine sediments around the Southern Middle Durance Valley (Provence, SE France): new evidences for a Tortonian age

Abstract

Based on burial dating by in situ produced cosmogenic nuclides (10Be, 26Al and 21Ne), and paleomagnetic analyses performed along the topmost 50 m of a 115 m long core retrieved from the Cadarache Area (Upper Provence, South East France), a Tortonian age was determined for the sedimentary succession exhibited in the core. In addition, thin sections, grain size analyses and quartz morphoscopy were used to characterize a shallow marine environment and to correlate the sediment core to the surrounding exposed sections. When comparing the studied sedimentary record to global sea level estimates, we establish that the Tortonian transgression was locally not synchronous with the global scale sea level high-stand, but happened more likely later, during a global regressive trend. The timing of the Tortonian flooding in Upper Provence was therefore most probably driven by regional tectonic forcings. Finally, the Tortonian shallow marine sediments are topped by lacustrine tight carbonates protecting the marine sediments from the following major erosional events resulting from the Messinian sea level drop and from interglacial-glacial fluctuations that both yielded to the present-day valley topography.