N-S-striking geological cross-section (see location on Fig. 1) across the eastern Basque-Cantabrian Basin associated with measured T_max data. (a) N-S cross-section from the South Pyrenean Frontal Thrust to the south to the Cinco Villas to the north (modified after Lescoutre and Manatschal, 2020). Higher T_max are restricted close to the northern part of the Nappe des Marbres along the Leitza Fault in the Nappe des Marbres (see location on Fig. 1) (b) Close-up on the Nappe des Marbres Basin with the distribution of the HT/LP metamorphism (modified after Ducoux et al., 2019) and relevant graph (T_max versus distance). The isograds were plotted with a margin of error.