X-Ray and Granulometric Analysis of Fluvial Sediment within the Gombe Sandstone Upper Benue Trough, Nigeria

Implication for Provenance, Paleoclimate, and Reservoir Quality Studies

Abstract

X-Ray and Granulometric Analysis was carried out on the Gombe Sandstone sediment exposed at Gabukka River, within the Upper Benue Trough, northeastern Nigeria. The research aim is to evaluate provenance and depositional settings, paleoclimate, paleoweathering, and reservoir quality potential of Gombe Sandstone sediment deposited along Gabukka River. Twenty (20) sediment samples were analyzed using granulometry, X-ray diffraction (XRD), and X-ray fluorescence (XRF). The sediment samples are composed of poor to moderately sort very fine to coarse grained particles, with predominantly fine-skewed and platykurtic distributions reflecting fluctuating hydrodynamic conditions typical of fluvial–deltaic systems. Mineral distribution shows quartz as the dominant mineral (41–69 wt.%) with subordinate feldspar, muscovite, and minor clay minerals (kaolinite and chlorite), indicating moderate to high compositional maturity and derivation from felsic continental source area. Elemental oxide composition is dominated by SiO₂ (65.8–78.9 wt.%) followed by Al₂O₃, Fe₂O₃, K₂O, TiO₂, CaO, MnO, P₂O₅, and MgO in variable concentration. Bivariate analysis between SiO₂ and other oxides indicate quartz enrichment through hydraulic sorting and heavy mineral and clay concentration in finer facies. The different weathering indices and the present of kaolinite confirm the dominance of intense chemical weathering under warm, humid climatic conditions. The research work concludes that sedimentary deposits along Gabbuka River are predominantly fluvial to fluvio–deltaic sediments deposited under oxidizing continental conditions. Reservoir potential is moderate to high, particularly within quartz-rich channel facies, but is locally reduced by clay enrichment and ferruginous cementation is anticipated.