Numerical Modelling of Salt-Detached Ramp-Syncline Basin Evolution: Effects of Base-Salt Ramp Geometry and Spacing

In salt-bearing passive-margin basins, base-salt ramps can organize supra-salt accommodation and the development of ramp-syncline basins (RSBs). Five two-dimensional geodynamic models were used to compare three combined single-ramp end-member geometries, in which ramp relief and dip covary at a fixed ramp width, and two dual-ramp configurations with contrasting inter-ramp spacings. Model responses were evaluated using basin morphology, axial-trace geometry, depocentre trajectories, stratigraphic thickness patterns, strain-rate fields and salt-velocity fields. The single-ramp models span a progression from weak supra-salt perturbation, through a coherent RSB with systematic basinward depocentre migration, to a partitioned, multi-centred response associated with localized salt thickening. These contrasts record the combined variation in ramp geometry. In the dual-ramp models, close spacing produces strongly overlapping accommodation and minibasin-style depocentre reorganization, whereas wider spacing preserves two more spatially separated depositional systems. Depocentre organization, migration style, axial-trace continuity and stratigraphic thickness patterns together provide forward-model reference patterns for evaluating candidate base-salt geometries when integrated with independent seismic and geological information.