The vast amount of Aptian salt deposited in the South Atlantic rift basins had a profound effect on the evolution of the Angolan segment of the West African passive margin. Analysis of recently acquired regional-scale seismic reflection data revealed a very broad range of salt-related structures including salt diapirs, ridges, pillows, rafts, tongues, and coalescing allochthonous salt sheets. These structures were subdivided into extensional and compressional features. The areal distribution of salt-deformational styles appear to be mostly influenced by the underlying basement structure, regional basinward tilt and the proximity to major sediment entry points into the basin, such as the Congo Delta.

The various salt-deformational styles also show a temporal/spatial evolution which was reconstructed by cross-section balancing of regional structure transects. Not only the severe internal deformation of the post-salt succession was restored but also its pre-kinematic position was determined relative to pre-salt markers, such as the basement high of the Atlantic ridge. The resulting model explains many pecularities of the stratigraphic evolution of the region directly impacting ongoing exploration efforts. To better understand the dominant driving mechanisms for the observed salt-induced stratigraphic patterns, basin-scale physical models were constructed. The experiments were specifically designed to study the influence of a rapidly growing delta succession on a preexisting rafted salt-domain in terms of salt-remobilization.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah