Provenance of the Ebenebe Sandstone: Evidence from X-Ray Fluorescence and Paleocurrent Studies

The Ebenebe Sandstone is the sandy member of the Paleocene Imo Formation. The sand body in Anambra State was subjected to x-ray fluorescence and paleocurrent analyses to establish the nature of the source rock, the paleoclimatic conditions of the source terrain, and the depositional environment. The research is to provide an insight into the Paleocene-Oligocene tectonic history and paleogeography of the Niger delta basin and the implications for the exploration and exploitation of sand and hydrocarbon resources in the region. Ten fresh and representative samples of the Ebenebe Sandstone were collected from Ugwuoba, Ifite-Awka, Isiagu and Ufuma outcrops respectively. The samples were subjected to X-ray Fluorescence analysis to determine the percentage concentrations of SiO2, TiO2, Al2O3, Fe2O3, MgO, Na2O, CaO, and K2O. At each location twenty sets of measurements of dips and azimuths of foreset planes of planar cross-beds were also taken for paleocurrent analysis. X-ray fluorescence studies revealed that the Ebenebe Sandstone is a silica-cemented quartz arenite composed of about 90.5% silica, with deleterious amounts of the oxides of aluminum, iron and titanium. Paleocurrent analysis revealed that the clastics were sourced from a pre-existing sedimentary terrain that lies to the east of the present study area. Chemical parameters further indicates that the terrain lies within a passive margin that experienced intense chemical weathering. It can therefore be concluded that the Ebenebe Sandstone was recycled from a pre-existing sedimentary terrain located to the east of the present study area that most probably became emergent as a result of the asymmetrical subsidence of the post-Santonian Anambra basin. These results thus provide new insight into the tectonic history of the Anambra-Niger delta basin complex.