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Terra Nova, 25, 110–118, 2013

Abstract

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).