40Ar/39Ar dating of a shoshonitic lava flow of the Radicofani volcanic center (Souther Tuscany)

A deeply eroded shoshonitic lava flow of the Radicofani eruptive center has been dated by Whole rock 40Ar-39Ar stepwise heating. The plateau age of 1299 +/- 3 ka agrees with the isochron age of 1305 +/- 5 ka. Small amounts of excess Ar are present; therefore previously reported K/Ar ages are very likely to be affected as well. The duration of the volcanic activity thus cannot be precisely calculated, but it is thought to have been short-lived.