Fission track dating on detrital zircons of Alpine debris in the Swiss molasse basin provides information about the erosion history of the Central Alps and the thermal evolution of source terrains. During Oligocene times, only sedimentary cover nappes, and Austroalpine basement units were eroded. Incision into Austroalpine basement units is indicated by increasing importance of Cretaceous cooling ages in granite pebbles upsection. Erosion of Penninic basement units started between 25 and 20 Ma. Early Oligocene zircon FT ages show that Penninic basement units were exposed at Ο 20 Ma. Deeper Penninic units of the Lepontine Dome became exposed first at Ο 14 Ma, contemporaneously with the opening of the Tauern window in the Eastern Alps. A middle Miocene cooling rate of 40 °C Myr-1 is deduced for the Lower Penninic units of the Lepontine Dome.
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