Geodynamic Numerical model outputs (animations) of "Late-Syn- to Post-rift Salt Tectonics on Wide Rifted Margins - Insights from Geodynamic Modelling" (Tectonics, 2022)

The geodynamic models of lithosphere extension and post-rift salt tectonics quantify different types of salt flow on rifted margins and test the effects of different salt viscosities (low, intermediate and high) on salt tectonics and margin evolution. The models show that updip extension balances largely with downdip diapir shortening, but that the distal salt nappe advance is largely unrelated to these processes. The salt nappes form by a combination of late syn-rift salt stretching and post-rift pressure-driven salt flow. This implies that the present-day width of salt nappes cannot be used as a constraint to balance updip extension on salt-bearing rifted margins. These observations have important implications for kinematic reconstructions of salt tectonics along rifted margins based on the common assumption of balanced salt deformation and for understanding the relationship between the distal edge of the salt basin and continent-ocean boundaries, important for plate-kinematic reconstructions.

Salt tectonics in all models exhibits three characteristic phases. 1) Syn-depositional salt flow and development of syn-salt-deposition minibasins resulting from stretching in the distal margin as salt is deposited during the last phase of rifting. 2) Emplacement of distal salt nappes on the early oceanic crust by stretching above the rift axis. 3) Post-rift sediment progradation and significant salt tectonics in the form of updip extension, translation, downdip diapir shortening, and pressure-driven salt flow and nappe advance. The occurrence of these distinct deformation processes (e.g., updip extension, translation, downdip shortening, syn-rift nappe stretching and post-rift nappe advance) is independent of salt viscosity, however, their magnitude, timing, as well as the style of salt deformation, vary.

Our models improve the current understanding of the dynamics of salt tectonics along rifted margins and the interplay between rifting and syn- to post-rift salt deformation associated with late syn-rift salt basins. The models are comparable to various examples of wide salt-bearing rifted margins such as the Brazilian, parts of West Africa, and Gulf of Mexico salt basins. They reproduce their observed crustal-scale architecture, regional salt tectonics styles, distribution of structural domains, and magnitudes of deformation.