Test of an irregular shape of the upper–lower crust limit on cross-section A. In (a), the case initially corresponding to a thin-skinned style (blue region in the parametric study, Fig. 4) remains in the same tectonic style when setting a bumpy upper–lower crust limit in (b). In (c–d) and (e–f), same test, but for and for , respectively. The case (c–d) shows a strong shift of tectonics from beyond the Jura in (c) to tectonics limited to the Molasse basin in (d).