The Benue Trough extends from the South where it merges with the
Niger-Delta to the North where its sediments are part of the Chad basin. The trough burficates
near its northeastern end and the northern branch continues beneath the Chad formation as an elongate depression that
extends well beyond Lake Chad. The Benue Trough is
a failed arm of a rift system of the Gulf
of Guinea, South
Atlantic and Benue Mesozoic triple junction whose centre is
occupied by the Niger Delta (Grant, 1971). Murat (1972) proposed three major
tectonic phases which took place in Albian, Santonian and late Eocene or early
Oligocene times. These major tectonic phase resulted in the formation and
subsequent remodeling of the
Benue trough. There are folds which consists of series of anticlinorium
and synclinorium suggesting that there was a deformational episode in the
trough. These folds, coupled with the identification of the igneous rock such
as andesites in the Abakaliki area which led some workers to propose a
compressional (subduction) rather than an extensional tectonic setting for the Benue trough (Farrington 1972; Burke et al., 1972). The floor of the Basin is irregular and sediments thicknesses
vary from place to place. This occurs as a result of extensive block faulting
initiated when the trough began to develop.