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Pliocene to Pleistocene Mass Transport Complexes in the Niger Delta Toe-Thrust: Analogs for Ancient Compressional Basins

Joan F. Flinch, Heinz Bachmann, Ignacio Brisson, Pier Luigi Corradini, and Cristina Muñoz Manzano
Repsol YPF, Madrid, Spain

The southeastern part of the Niger Delta in Equatorial Guinea is occupied by SE-vergent compressional imbricates associated with toe-thrusting and a related flexural basin (Bioko Basin). Deep water shale, turbiditic sandstone and widespread Mass Transport Complex deposition occured during Neogene time within the frontal compressional imbricates and flexural basin of the study area. MTCs represent a great percentage of the deposits that occur within thrust bounded synclinal basins. MTCs are characterized by rear fault scar features, lateral strike-slip faulting and frontal compressional ridges, convex in the transport direction. MTCs are initially (in an up-slope position) perpendicular to slope breaks which are parallel to thrusts and folds and turn into and become parallel to synclinal axes. MTCs tend to develop along incised canyon areas, while widespread creeping occurs between canyon areas. MTC deposition is coeval in time and parallel to meandering turbiditic channels that are deposited along the same synclinal axes. The study area, with complete 3D coverage, in a preserved deep water setting represents a unique and excellent analog of MTC deposition in compressional basins of ancient folded belts, like the Pyrenees. There are no outcrop limitations like in field examples and the structural setting is similar. In the prolific Golden Triangle of Nigeria, Equatorial Guinea and Cameroon, MTCs play a major role as seals and locally as reservoirs of oil and gas fields.