--> Growth Extensional Fault-Related Folds in Salt Basins: A Case Study of the Interplay Between Salt Dynamics and Extension in the West Africa

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Growth Extensional Fault-Related Folds in Salt Basins: A Case Study of the Interplay Between Salt Dynamics and Extension in the West Africa

Abstract

Abstract

Salt-detached rollovers are unique extensional structures in that the footwall and base level material is weak and mobile over geologic time. Yet, analytic fault-related folding techniques can be directly applied to determine the timing and kinematics of rollover development. Using 3D seismic reflection data from a salt basin in West Africa, it is shown how the interplay between fault slip, sedimentation within developing accommodation space, and salt mobility generate the diagnostic depositional geometries commonly associated with these structures. Syn-tectonic growth sedimentation accurately captures the role salt migration and pure extension play in the development of these structures, where salt migration in the footwall can characteristically alter the patterns of hanging wall geometries after or during extension. By recognizing the balance between these two mechanisms, the application of fault-related fold interpretations allows us to determine the paleo-location and geometry of depocenters throughout their evolution. These techniques offer insight into how the basal salt has changed during extensional fault slip, the relative sense of motion along isolated “rafted” blocks, and the relative contribution of sedimentation vs. accommodation space development in a regional context.