Deformation Patterns in Western Offshore Libya: Partial Decoupling of Strike-Slip and Salt Tectonics

Summary The study area is located in the Gabes-Tripoli (G–T) Basin in western offshore Libya. There are today unsolved questions concerning the tectonic and stratigraphic processes that controlled both basin evolution and reservoir development through time. This study presents interpretations of the tectonic system in the G–T Basin based on 3D-seismic-reflection data and 13 industrial wells. This research uses a workflow specifically designed to enhance the seismic interpretability of faults. The workflow integrates 3D-seismic data pre-conditioning, surface attributes, isochore maps and rose diagrams. Subsurface attribute interpretations show that (1) different groups of faults with different structural orientation characterise different stratigraphic intervals; (2) major anticlines (associated with the main hydrocarbon reservoirs) trend WSW-ENE and SSE-NNW, which is oblique to the dominant NW-SE fault trend; (3) large N–S oriented, synsedimentary listric normal faults formed at the edges of major anticlines bounding kilometre-scale depocentres; (4) anticline growth and growth faulting at the anticline edges is decoupled from the dominant NW-SE fault trend. This study documents partial decoupling of overburden faulting in the western study area from otherwise dominant strike-slip tectonics, indicating that lateral and vertical salt movement in the deeper subsurface exerted a major control on deformation patterns in the offshore G–T Basin.