Fig. 6

Model of the greenschist-facies structural evolution of the DBBT between ~43 and 32 Ma; black arrows indicate movement directions; grey arrows indicate areas of dominant compression and extension, respectively. a ~43–39 Ma: Ductile top-(N)W shearing along the DBBT led to formation of greenschist-facies mylonitic fabrics; this phase was associated with main exhumation of the Dent Blanche nappe from high-pressure to greenschist-facies conditions and reactivation of the former subduction interface along the DBBT as a thrust; GS-facies deformation and retrogression also penetratively affected the underlying Combin zone. b ~38–37 Ma: A phase of normal-sense top-SE shearing was mainly localized within rheologically weak Combin calcschists, while the DBBT experienced only partial reworking. c ~36–35 Ma: Ductile deformation under medium- to low-grade greenschist-facies conditions due to increasing underthrusting of European continental margin units and resulting updoming of the nappe stack; bulk top-NW shearing along the southeastern DBBT was accompanied by conjugate top-SE shearing, especially towards the SE, interpreted to reflect a regional pure shear geometry during NW–SE directed crustal extension. d ~34–33 Ma: The DBBT was subject to orogen-perpendicular shortening due to an increase in Europe-Adria convergence leading to formation of folds and crenulations. e ~32 Ma: Exhumation of the DBBT across the ductile–brittle transition during incipient formation of the Vanzone antiform led to bulk normal-sense top-NW shearing along the southeastern DBBT and conjugate top-NW/-SE shearing