Selective inversion of rift basins in lithospheric-scale analogue experiments

Abstract. Basin inversion is commonly attributed to the reverse reactivation of normal basin-bounding faults. This association implies that basin uplift and inversion-related structures are mainly controlled by the frictional behaviour of pre-existing faults and associated damage zones. In this study, we use lithospheric-scale analogue experiments of orthogonal extension followed by shortening to explore how the flow behaviour of ductile layers underneath rift basins promote or suppress basin inversion. Our experiments show that the rheology of the ductile lower crust and lithospheric mantle, modulated by the imposed bulk strain rate, determine: (1) basin distribution in a wide rift setting and (2) strain accommodation by fault reactivation and basin uplift during subsequent shortening. When the ductile layers deformed uniformly during extension (i.e., stretching) and shortening (i.e., thickening), all of the basins were inverted. When viscous deformation was localised during extension (i.e., necking) and shortening (i.e., folding), only some basins – which were evenly spaced apart – were inverted. We interpret this selective basin inversion to be related to the superposition of crustal-scale and lithospheric-scale boudinage during the previous basin-forming extensional phase.