GEOLOGY AND SEDIMENTOLOGY OF DUMBULWA MEMBER OF PINDIGA FORMATION IN GONGILA AND ENVIRONS, GOMBE STATE.

ABSTRACT This study investigates the sedimentary framework of the [Dumbulwa member] Pindiga formation, through integrated field mapping, granulometric, and petrographic analyses. The lithostratigraphy is dominated by sandstones with interbeds of shale, mudstone, and limestone, reflecting deposition in a mixed fluvio-deltaic to shallow marine system. Granulometric results show variable grain sizes from medium to coarse with poor to moderate sorting, indicating fluctuating depositional energy from fluvial to shoreface environments. Statistical parameters highlight short transport for feldspathic sandstones and extensive reworking for quartz-rich varieties. Petrographic examination and QFL plots classify the sandstones as arkosic, feldspathic litharenites, and subarkosic types, with maturity levels ranging from immature to mature. These variations suggest a polycyclic provenance involving granitic–gneissic basement rocks, reworked sedimentary units, and recycled orogenic sources. The limestone within the study area occurs as fibrous, fine-textured beds representing deposition in calm low-energy marine environment. Overall, the combined lithological, textural, and compositional evidence points to a tectonically influenced basin where sediment supply and sea-level fluctuations controlled deposition with reduced energy phases, offering insights into the sedimentary evolution and provenance history of the area.