Fig. 3

a Synthetic map of the regional best σ3 axes determined from the statistical analysis of paleostress databases available around the bend of the Alps (see text for details). The stereonets (or only the best axes in red drawn from the corresponding publication for the localities c, g, k, where numerical datasets are unavailable) correspond to the Tauern Window (a, b; Bertrand et al. 2015; and c Wang & Neubauer 1998), the Bergell pluton (d; Ciancaleoni and Marquer 2008), the Lepontine Dome (e; Allanic 2012), the vicinity of the Simplon fault (f: Grosjean et al. 2004), the Valais area (h; Champagnac et al. 2003), the Aosta area (i; Champagnac et al. 2004; g; Bistacchi and Massironi 2000), the Vanoise area (j; Champagnac et al. 2006), The Cotian Alps (k; Perrone et al. 2011), the Briançon area between the Pelvoux, Viso and Argentera massifs (l, m; Sue and Tricart 1999; 2002; 2003 and n Bauve et al. 2014), and the Penninic units north of the Argentera massif (o; Beucher 2009). In red, σ3 for the major orogen-parallel extension signal; in blue, σ3 for the minor orogen-perpendicular extension signal recognized in the core of the Western Alpine arc (see text for details). See Fig. 1 for geological caption. b Set of statistical stereonets for each of the dataset plotted in a. Each stereonet presents the contouring of the overall related paleostress σ3 axes, together with the corresponding rose-diagram (Stereonet© software, Allmendinger et al. 2013; Cardozo and Allmendinger 2013). Due to their internal regional variability, the datasets of the Tauern Window, Valais-Vanoise and the Briançonnais areas have been subdivided into 2 or 3 regional stereonets. The corresponding parameters are given in Table 1, including the best σ3 directions in the (0°–180°) range (Bingham axial distribution, see Allmendinger et al. 2013 Cardozo and Allmendinger 2013). The overall paleostress/strain database (727 tensors) is available as supplementary material together with the corresponding maps