Print this pageAbstract: Lower Congo Tertiary Basin - Offshore West Africa Structural Zonation and Evolution
Raillard, S. - Elf E&P, France; Biteau, J. J. - Elf Exploration Angola; P. Allix and C. Chevalier - Elf E&P
Gravity tectonics over a salt decollement characterizes deformation of the Albian to Recent series in the Lower Congo Basin, offshore West Africa.
The whole tertiary basin displays a typical East-West tectono-sedimentary zonation with an updip extensional domain accommodated by a downdip contractional domain.
The extensional domain presents a large slump scarp geometry with a central area where the cretaceous series has undergone an oceanward translation of up to 70 Km. North and Southward, the amount of translation decreases down to less than 10 Km. The Tertiary infiling of the extensional domain corresponds to an up to 8000 m thick silici-clastic sediment pile.
The structural zonation of the contractional domain is directly controlled by the North-South variation of translation along the updip extensional domain. The central maximal amount of translation (70 Km), is accommodated by large reverse faults often associated with allochtoneous salt tongues to the East and large allochtoneous salt sheets more or less coalescent to the West. Northward and Southward, the contractional accommodation of the updip translation evolves gradually to large scale symmetrical salt cored folds.
The extensional and contractional domains are separated by a complex structural area, characterized by structural inversion displaying reactivation of older folds and thrusts in extension or previous extensional diapir and listric faults in contraction.
AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil