Fig. 4

Zircon U–Pb concordia plots for three igneous rock samples from the Siviez-Mischabel nappe. Weighted mean calculations are presented for populations of more than 90 % concordant analyses. a The orthogneiss slice of Illsee (636) shows a Cambrian-Ordovician crystallization age. b The orthogneiss slice from Le Bautsé (687) is related to the Permian magmatic activity of the Randa intrusion. c The Thyon orthogneiss (667) shows a Cambrian age of intrusion. Colored ellipses correspond to more than 90 % concordant data, gray ellipses to less than 90 %. Errors are reported at the 2σ-level