Geology, Geochemical and Petrographic Studies of Lokoja Sandstone Facies: Implications on Source Area Weathering, Provenance and Tectonic Settings

Abstract

The examination of the geology, petrographic and geochemical profiles of the Lokoja sandstone facies is the primary goal of this research. The objectives include carrying out geochemical analysis on the Lokoja sandstone facies, carrying out X-ray fluorescence (XRF) analysis within the Lokoja sandstone facies, carrying out X-ray diffraction (XRD) analysis within the Lokoja sandstone facies and the determination of the petrographic of the Lokoja sandstone facies. A few thin oolitic iron stones and coarse-grained cross-bedded sandstone make up the geology of the study area, along with pebbly clayey grit and sandstone. Rarely exposed has been identified as a basal conglomerate composed of well-rounded quartz pebbles embedded in a white clay matrix. ranging from 100 and 300 meters in thickness, depending on the relief of the Basement Complex floor beneath. The methods used in carrying out this project research include granulometric, geochemical, and petrographic analysis. The result from the granulometric analysis was used to construct the lithology log. The log helps to determine the paleo-environmental and depositional sequence of the study area. The XRD/XRF analysis shows Quartz and Orthoclase Feldspar, as the predominant mineral assemblage recommending a low weathering contour for the Lokoja sandstones. The mineralogical composition of sandstones was detected using XRD and XRF analyses. The XRD profile of the Lokoja Sandstone A which is situated around the Nataco area consists of the following mineral obtained during the XRD: quartz, orthoclase, muscovite, kaolinite, osumilite, illite, chlorite and garnet respectively with varying percentages. The major minerals obtained from the results were quartz (67%) and orthoclase feldspar (11%). Geochemical signatures of clastic sediments can be employed to interpret the provenance nature of the deposits. The Al₂O³ /TiO₂ for Lokoja sandstone, claystone and shale facies of Patti Formation are 52.43 wt %, 14.21 wt %, 10.02 wt % and 10.25 wt % equally. This proportionality suggests felsic source rock for the Lokoja Sandstone and intermediate source rock for the Patti sediments. The Geology (distribution), Provenance, Weathering, Tectonic context and redox proxy of the Lokoja Sandstone, Middle-Niger basin have been determined using integrated petrographic, granulometric and geochemical advent. Major elements geochemistry and their ratios affirmed that the Lokoja sandstone is predominantly mature lithic arenites including sub-greywacke and protoquartzites impact of felsic igneous provenances on the static basin