The primary depositional structures of the Upper Bima Member from Fufore and environs, Yola Arm of the Upper Benue Trough, Northeastern Nigeria: implications for paleoenvironment

Primary depositional structures are important parameters that can provide the means of unraveling the processes and process responses in sedimentary depositional settings. This paper is aimed at determining the paleoenvironment of the Upper Bima Member in Fufore and environs using the primary depositional structures. This research was carried out in two phases which involved fieldwork that dealt with logging the outcrops sections and desk work whereby the logged sections and other field data are digitized, remodeled and analyzed using relevant computer programs. The result of the study shows that the Upper Bima Member is composed of five lithofacies succession; trough cross-bedded sandstone facies (St), planar cross-bedded sandstone facies (Sp), horizontal bedded sandstone facies (Sh), ripple cross-laminated sandstone facies (Sr), and mudstone facies (Fm). These lithofacies gave rise to two facies associations; sand dominated and fine-grained facies dominated facies association. The cross-stratified facies show an overall paleocurrent trend in the NW direction. These facies succession represent both shallow perennial and ephemeral sand-bed in a braided river depositional environment.