Actual and ancient uplift rate in the Gotthard region, Swiss Alps : A comparison between precise levelling and fission-track apatite age

Along the St. Gotthard road, crossing the central part of the Swiss Alps, precision levellings have revealed evidence of uplifts which are expressed by a general and symmetrical bulging with a local average rate of up to 1 mm/year. The fission-track dating of twenty samples of apatites taken in the granitico-gneiss rocks of the Aar and Gotthard Massifs permits the determination of the deformation undergone by the paleoisotherms (approximately 120°C) of different ages. As determined by this method, the average rate of uplift (0.3-0.6 mm/year) 6–10 m.y. ago, is similar to that of the present day.