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Regional Paleogeographic Evolution of West Previous HitAfricaNext Hit: Implications for Hydrocarbon Exploration

HEMPTON, M. R., M. A. ROSEN, R. M. COUGHLIN, A. D. SCARDINA, E. S. HAGEN, and P. J. NORDSTROM, Pecten International Company, Houston, TX

New paleogeographic reconstructions of west African continental margins provide a regional framework to contrast differences in hydrocarbon habitat and tectonostratigraphic style. Five regional provinces are delineated: (1) Northwest Previous HitAfricaNext Hit margin from Mauritania to Sierra Leone, (2) Transform margin from Liberia to Benin, (3) Niger delta of Nigeria, Cameroon, and Equatorial Guinea, (4) South Atlantic Salt basin margin from Cameroon to Angola, and (5) Southwest Previous HitAfricaNext Hit margin of Namibia and South Previous HitAfricaNext Hit.

Computer-constrained paleogeographic reconstructions based on exploration data depict the separation of west Previous HitAfricaNext Hit from South and North America during the Late Triassic to the present along three rift systems. In northwest Previous HitAfricaNext Hit rifting began in the Late Triassic associated with the opening of the Central Atlantic. In southwest Previous HitAfricaNext Hit rifting began between the southern tips of Previous HitAfricaTop and South America in the Early Cretaceous (Valanginian) and propagated northward to the Benue Trough, a broad zone of left-lateral shear and extensional basins that began to open in the Aptian. Between these two rift systems, the Transform margin rift system initiated in the Early Cretaceous (Barremian) as a wrench-fault dominated eastward extension of the Proto-Caribbean ocean that propagated to the Be ue Trough by the middle Albian.

The most important variables affecting the tectonostratigraphic and hydrocarbon evolution of the west African margins include (1) the geometry, kinematics, and duration of rifting; (2) distribution of rift basins relative to paleoclimate zones (which affects the deposition of lacustrine source rocks and evaporites while influencing the type and quantity of sediment derived from land); (3) sea-level fluctuations; and (4) distribution of deltaic and turbiditic depocenters.


AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)