Title : Geological evolution, structural controls, and petroleum potential of the MSGBC basin: Insights and discussion
Abstract:
The MSGBC Basin, a passive margin basin on the Northwest African Atlantic Margin, originated in response to the opening of the proto-Central Atlantic Ocean. Basin initiation is inferred to have occurred during a Late Triassic rifting phase, evidenced by seismic data in onshore Mauritania and well-documented on conjugate margins in Morocco and the eastern seaboard of North America. Although syn-rift faults bound the rifted succession, these structures are largely absent in the post-rift stratigraphy. The Early Jurassic rift-drift transition is dominated by evaporite deposition, likely the source of offshore salt diapirs, and acted as a detachment surface for subsequent gravity-driven tectonics. From the Middle Jurassic to Valanginian, a semi-regional carbonate platform developed along the basin margins, later terminated by a rapid Valanginian transgression and Barremian clastic deposition in Mauritania. Post-Valanginian stratigraphy records several third-order clastic cycles punctuated by transgressive carbonates, corresponding to source rock deposition during Cenomanian–Turonian, Paleocene, and possibly Late Aptian–Early Albian intervals. Lowstand periods favored turbidite deposition in Mid Cenomanian, Late Maastrichtian, Middle Miocene, and Late Miocene, forming either unconstrained or canyon-confined deepwater fairways. The Neogene succession is characterized by a rapidly deposited clastic wedge exceeding 3 km in thickness along the basin axis, driving maturation of underlying Turonian source rocks into the oil window. Structural evolution of the post-rift section is dominated by gravity-driven tectonics, with Early Jurassic evaporites and Late Albian detachment levels controlling subsidence, growth faulting, and toe thrust formation. Reactive salt diapirism developed during compressional toe thrusting, with Miocene progradation shifting depocentres basinward, generating a new gravity-driven system. Salt diapirs, once topographically significant, became truncated and inactive, while continued shelf- edge growth induced localized compression over these structures.
Overall, the MSGBC Basin exhibits a complex interplay of syn- and post-rift tectonics, carbonate platform evolution, clastic progradation, and salt tectonics, controlling hydrocarbon source rock maturation, reservoir distribution, and structural traps, highlighting its significant petroleum potential.
