A Provenance Study of the Paleogene Lithostratigraphic Units of the Niger Delta: An Insight into the Plate-Tectonic Setting

Integrated heavy-mineral analysis and paleocurrent characteristics of the outcropping Paleogene strata of the Niger Delta Basin, southeastern Nigeria were studied in order to reconstruct the provenance, with an emphasis on the sandstone maturity and tectonic setting. The depositional environment of the strata in the study area is a shallow marine to shoreline deposit, which records the transgressive and regressive episodes of three outcropping Paleogene strata (Imo, Ameki, and Ogwashi formations). The regional paleocurrent pattern shows predominance of bimodal WNW and ENE paleoflow directions with a high to medium variance. The integration of the heavy minerals and paleocurrent analyses show a mixed provenance of low- to high-grade metamorphic, igneous and reworked older sedimentary sources that lie southwest, southeast and east of the study area. The major source terrains are the Oban Massif and pre-Santonian sedimentary units of the Southern Benue Trough to the southeast and east, as well as the gneisses and schists’ belt of the West African Massif to the southwest of the study area. The zircon-tourmaline-rutile (ZTR) index indicates that sandstones are mineralogically immature to mature, while the triangular plot of MF-MT-GM suites shows that the sediments were deposited in a mature passive continental margin on the stable craton of the African plate.