The West African salt-bearing rifted margin—Regional structural variability and salt tectonics between Gabon and Namibe

Abstract

Salt-bearing rifted margins comprise some of the most structurally complex and economically important sedimentary basin settings such as the South Atlantic and the Gulf of Mexico salt basins. They are also involved with some of the largest uncertainties regarding the crustal and syn-rift basin architecture and supra-salt tectonic evolution, as well as the link between rifted margin architecture with salt deposition and post-rift gravity-driven salt tectonics. We thus conduct a margin-scale study along nearly the entire West African salt basin, from South Gabon to Namibe, combining a vast data set of 2D and 3D seismic and well data with gravimetric and magnetic data to analyse its along-strike rift and salt tectonic structural variability. We construct regional structural and thickness maps of key salt and post-salt intervals to depict the history of individual margin segments and to investigate (1) how rifting and rifted margin architecture influences post-rift salt tectonics evolution, (2) how these vary through time and space and (3) what are the controls between their different salt tectonic styles. We show that rifting and rift structures controlled the salt basin geometry, thickness and base-salt relief in different ways for the different margin segments, and drastically influenced their post-rift salt tectonic evolution. Differences in post-salt sediment supply and continental uplift also had a role in their salt tectonic evolution. The results also have general implications to understand the interplay between rifted margin architecture with post-rift salt tectonics for salt-bearing rifted margins.