f Neogene Gravity Tectonics and Depositional Processes on the Deep Niger Delta Continental Margin

The continental margin off the Niger Delta is undergoing deformation by gravity tectonism caused by rapid seaward sediment progradation. Three regional structural styles are recognized: (I) an upper extensional zone of listric growth faults beneath the outer shelf; (II) a translational zone of diapirs and shale ridges beneath the upper slope; and (III) a lower compressional zone of imbricated thrust structures (toe thrusts) beneath the lower slope and rise. Linked together on a regional scale, these styles suggest that large portions of this thick sediment prism are slowly moving downslope by gravity gliding or sliding, in a manner somewhat analogous to giant massmovements or mega-landslides. This deformation has created local intraslope basins up to 25 km wide, which are generally filled with thick (up to several km) turbidites and mass-transport deposits.