Dating of lithospheric buckling: 40Ar/39Ar ages of syn-orocline strike–slip shear zones in northwestern Iberia

摘要: Abstract Orogenic curvature is a ubiquitous feature of mountain belts, and the plate tectonic geodynamic setting responsible for development curved orogens subject debate. In order to distinguish between different models orocline formation it necessary tightly constrain absolute timing oroclinal development. However, determining (isotopic) bending challenging. The most direct method available time interval during which an formed obtain age constraints on fabrics generated within syn-orocline strike–slip shear zones that accommodated rotations around vertical axis crustal or lithospheric scale orogenic curvature. Here we present data set 40Ar/39Ar ages obtained from five shear-zones, some display traces parallel Cantabrian Orocline structural grain in NW Iberia are interpreted have been coevally it. were by laser-rastering induced step-heating single muscovite crystals grew synkinematically shearing. All samples yielded cluster at 308 ± 3 Ma providing evidence bending. This consistent with paleomagnetic place onset Moscovian times. Our determinations therefore provide reliable constraint buckling Variscan orogen further unrelated convergence/collision subsequent extensional collapse belt.