How post-salt sediment flux and progradation rate influence salt tectonics on rifted margins: Insights from geodynamic modelling

Continental rifted margins can be associated with widespread and thick salt deposits, which are often formed during the final stages of rifting, prior to breakup. These salt-bearing margins are typically characterized by pronounced post-rift salt tectonics with variable and complex structural styles and evolution. We use a lithosphere-scale geodynamic numerical model to investigate the role of varying post-rift sediment fluxes and progradation rates on rifted margin salt tectonics. We focus on a single, intermediate, rifted margin type and salt basin geometry to explore scenarios with different: (i) constant and (ii) time-varying post-salt sediment fluxes. We demonstrate that these promote significant contrasts in the style and magnitude of salt tectonics in the proximal, transitional and distal margin domains. The differences are primarily controlled by the relationship between the rates of sediment progradation (V-prog) and salt flow (V-s). When V-prog > V-s, the salt is rapidly buried and both vertical and lateral salt flow are suppressed across the entire margin. When V-prog < V-s, the salt flows vertically and seaward faster than sediments prograde producing major diapirism in the proximal domain and major distal nappe advance, but only moderate overburden extension and distal diapirism. When V-prog similar to V-s, there is moderate proximal diapirism and distal nappe advance, but major updip extension and downdip shortening, which produces major distal diapirism. Modelling results are comparable to various natural systems and help improve our understanding of the controls and dynamics of salt tectonics along salt-bearing rifted margins.