Fig. 1

A Overview of tectonic realms in the Geneva Basin for the FCC construction with analysed well and outcrop locations. Geophysical well-logs were digitized and analysed together with available rock core data from these wells. See Table 1 for well numbers and full well-IDs. The overlying Quaternary deposits are neglected for increased readability. The blue line depicts cross section A, the green line refers to cross section B (Figs. 5, 6). Note that the Salève and Mandallaz limestone as commonly referred to in technical reports are part of the Jura. FTB fold-and-thrust belt. B The white profile X–Y displays a large-scale cross section through the Geneva Basin and is based on chronostratigraphic units representing the vertical and spatial relationships of age-defined packages of lithologies in a geo-historical picture. The FCC’s current subsurface tunnel alignment is currently foreseen at a depth interval between 100 to 300 m ASL. The Burdigalian Molasse belongs to the Upper Marine Molasse and is hereby noted Marine Molasse. Data compiled, amended and modified after Bachmann & Müller, 1991; Charollais et al., 2013; Clerc & Moscariello, 2020; Deville et al., 1994; Haq et al., 1987; Kuhlemann & Kempf, 2002; Lemcke, 1988; Mastrangelo & Charollais, 2018; Moscariello, 2019, 2021; Zweigel et al., 1998