Fig. 3

a Cross-section along the Bedretto tunnel based on the profile of Keller and Schneider (1982), data from the tunnel section of Schneider (1985), and data from this study. Background colors correspond to geological units in the overview map (Fig. 1). White dots indicate origin of Rotondo granite samples used for the analysis of microstructures (Sect. 3.2.4), gray dot indicates sample of a G-SZ used for the analysis of microstructures (Sect. 3.2.4), and yellow stars indicate samples used for investigations based on zircons (Sect. 4). The cross-section is simplified in order to highlight the most important structural features. Note the general upward movement of the northern block as well as the increasing occurrence and increasing steepness of the shear zones in the Rotondo granite towards NW. b Dip direction (upper plot) and corresponding dip (lower plot) of the foliation, brittle fault zones, and ductile shear zones as a function of distance along Bedretto tunnel. The arrows on the top of the figure mark sectors considered in the sub-figures of Fig. 4