Neogene exhumation history of the Bergell massif (southeast Central Alps)

International audience; The Bergell pluton is an elongated plutonic body emplaced during Oligocene time along the Insubric line in the central Alps. Reconstruction of its exhumation, based on apatite (U-Th)/He dating and one-dimensional thermal modelling, provides evidence for a three steps history: (i) following initial fast exhumation from >20-25 to ∼17 Ma, slow down of the exhumation rate until ∼10 Ma, (ii) quiescent phase from ∼10 to ∼5-6 Ma and (iii) an apparent increase of exhumation after ∼5-6 Ma. The decrease in exhumation rate is related with migration of thrusting south of the Bergell area in the Southern Alps (Lombardic phase). Increase in exhumation rate after ∼5-6 Ma is possibly related with Messinian base level drop, enhanced climatic variability (3-4 Ma) and intensification of glaciation (∼0.87 Ma).