Fig. 2: Evolution of the Caledonian crust from end convergence (Early Devonian) to completely collapsed crust (Middle Devonian).
From: The North Sea rift basement records extensional collapse of the Caledonian orogen
a End continental subduction. b Early extensional stage with eduction of the Baltica margin and uniform hinterland-directed transport of the orogenic wedge above the Baltican basement. c Advanced collapse stage, where the crust is heated and softened, promoting vertical movements in the form of doming and metamorphic core complex formation. d More detailed view of the Øygarden metamorphic core complex (CC) and its bivergent shear zone system (present-day erosion level). Pink zones indicate extension-related shear zones in the deeper basement, reworked by the Bergen Detachment. Black lines mark late-stage strain localization features, mostly ductile but with a late brittle stage. Note that the North Sea rift postdates this Devonian extensional deformation. (U)HP (ultra)high pressure, BASZ Bergen Arc Shear Zone, HSZ Hardangerfjord Shear Zone.
