Fig. 1
a Map of the Western and Central Alps showing the Schistes Lustrés units; modified after Schmid et al. (2004, 2017), Steck et al. (1999, 2015, 2019), Ballèvre et al. (2018, 2020), Beltrando et al. (2010, 2014), Balestro et al. (2020), Dal Piaz (1999), Bigi et al. (1992), Gouffon (1993), Deville et al. (1992) and the Tectonic map of Switzerland (2005). A: Antrona nappe; Ac: Accelgio zone; AF: Aosta fault; ALi: Apenninic Ligurian nappes; Am: Ambin massif; Ar: Arpont massif; B: Breccia nappe; Bi: Biella pluton; Br: Brusson window; BT: Brèches de Tarentaise; CB: Pancherot - Cime Bianche - Bettaforca Series; Ch: Chenaillet unit; CN: Cheval Noir Flysch; Dr: Dranses nappe; DS: Dronero-Sampeyre unit; Em: Monte Emilius unit; Ga: Gastern massif; Ge: Gets nappe; GI: Gazzo-Isoverde unit; Gr: Graies Alps; GR: Glacier-Rafray unit; Gu: Gurnigel nappe; HF: Helminthoid Flysch; La: Lanzo massif, LA: Ligurian Alps; LTF: Lis-Trana fault; M: Money unit; MF: Mont Fort nappe; MV: Monviso massif; Ni: Niesen nappe; NVa: Northern Vanoise massif; Or: Orobic nappes; Pg: Portjengrat nappe; Pi: Pillonet unit; R: Ruitor unit; RC: Roche des Clots unit; Ro: Rochebrune unit; S: Stockhorn nappe; Sa: Saane nappe; SaM: Subalpine Molasse; SC: Sion-Courmayeur zone; Si: Simme nappe; SM: Siviez-Mischabel nappe; SVa: Southern Vanoise massif; T: Traversella pluton; Ta: Tavetsch nappe; TL: Tonale Line; Ts: Tsaté nappe; V: Voirons nappe; Vo: Voltri massif; Vs: Valsavarenche unit; ZH: Zone Houillère; ZS: Zermatt-Saas Fee nappe. b Map of the Schistes Lustrés of the Combin zone and surrounding units across the Bagnes, Dix, Hérens and Anniviers valleys in SW Switzerland, and the Ollomont valley and Valpelline in NW Italy; bedrock map compiled after our own and the maps of Moix and Stampfli (1980), Escher (1988), Allimann (1990), Rey (1992), Kramar (1997), Burri et al. (1998), Baillifard (1998), Steck et al. (1999), Favre (2000), Marthaler et al. (2008a, 2020a), Sartori et al. (2011), Sartori and Epard (2011), Glassey (2013) and Geocover (Swisstopo). The individualized “Tracuit - Aig. Rouges z. / Cornet U.” groups together the Tracuit - Aiguilles Rouges zone with the Cornet Unit; limits after Marthaler et al. (2020b, fig. 16) and Manzotti et al. (2021, fig. 7), slightly modified. AR: Aiguilles Rouges d'Arolla; DBM: Dent Blanche Mesozoic; SMM: Siviez-Mischabel Mesozoic; ZHM: Zone Houillère Mesozoic; ZHP: Zone Houillère Paleozoic