Cretaceous and late Cenozoic uplift of the eastern French Massif Central: insights from low- temperature thermochronometry

International audience; Apatite fission-track and (U-Th)/He thermochronometry have been applied to investigate the long-term topographic evolution of the French Massif Central. Located in the foreland domain of the Alpine and Pyrenean mountain belts, the French Massif Central presents enigmatic topographic features, reaching ~1700 m a.s.l. and ~1000 m of relief, that did not originate from Alpine compressional nor from extensional tectonics. The age of the present-day topography, the timing of its formation, and the underlying processes remain debated. Our new thermochronological data come from the eastern flank of the massif, where sampling profiles run from the high-elevation region down to the Rhône river valley floor with a total elevation profile of 1200 m. Age-elevation relationships, mean track-length distributions and thermal modeling indicate a two-steps cooling history: (i) a first exhumation event, already detected through previously-published thermochronology data, with an onset time during Mid-Cretaceous; and interestingly (ii) a more recent Cenozoic phase that is resolved from our data, with a likely post-Eocene onset. This second erosional event is associated with relief formation and valley incision probably induced by a long wavelength domal uplift supported by mantle upwelling. Disclaimer: This is a confidential document and must not be discussed with others, forward in any form, or posted on websites without the express written consent of the Geological Society of America.