K-Ar fault gouge dating of Neogene thrusting. The case of the siliciclastic deposits of the Trasimeno Tectonic Wedge (Northern Apennines, Italy)
The Northern Apennines (NA) are a characteristic example of foreland fold-and-thrust belt progressively migrating towards its foreland. Their tectonic evolution has been quite tightly constrained in time by microfossil biostratigraphy applied to syn-orogenic deposits within foreland basins. This makes the NA well suited to test the reliability of K-Ar illite dating of Neogene deformation affecting siliciclastic sequences. We sampled two top-to-the-ENE thrusts, whose well defined cores are defined by scaly gouge formed at the expense of the pelitic component of the host rock.