The lateral strike-slip domain in gravitational detachment delta systems: A case study of the northwestern margin of the Niger Delta

Abstract

We use two- and three-dimensional seismic data to describe the structural geology of the lateral margin of a deep-water delta lobe within the Niger Delta that has undergone basinward, gravitationally driven translation. We term this region the “lateral strike-slip domain.” Deformation is characterized by a strike-slip fault system that can be followed for a distance of approximately 75 km (47 mi) from the shelf to the slope and toe of slope. On the northwestern side of the fault system, a fold and thrust belt that propagated north to northwest has developed within a large-scale restraining area of 460 km2 (180 mi2). On the southeastern side of the strike-slip fault system, widespread extension has occurred, characterized by several graben and kilometer-scale rollover structures. Lateral margins of gravitational collapses give key information on how they deformed. We estimate a minimum horizontal displacement on the main strike-slip fault of approximately 7 km (4 mi). Structural and kinematic evidence, such as present-day propagating strike-slip faults, for possible future lateral expansions of the lateral strike-slip domain, is described. We expect to observe similar sets of deformation styles at the margins of other preserved gravitational collapse sliding over a detachment whose efficiency in causing downdip slip may vary laterally.