Sedimentology and Geochemistry of Bima Sandstones around Hinna, Gongola Basin, Northern Benue Trough: Implications for Paleoenvironment, Provenance, Tectonic Setting, and Paleo-Weathering

Abstract

The Bima Sandstone represents the earliest continental infill of the Gongola Basin within the Northern Benue Trough, formed during Early Cretaceous intracontinental rifting associated with the opening of the South Atlantic. This study integrates sedimentological logging, petrography, heavy-mineral analysis, and major–trace-element geochemistry to reconstruct the depositional environment, provenance, tectonic setting, and paleoweathering history of the Bima Sandstone exposed around Hinna. Facies analysis identifies three genetically related facies associations—proximal braided river, braided river in-channel, and floodplain/overbank—indicating deposition in a high-energy braided fluvial system with upward transition to lower-energy overbank settings. Petrographic results classify the sandstones as arkosic to lithic arkosic, dominated by quartz and feldspar with subordinate lithic fragments, reflecting short transport distances and rapid sediment supply. Heavy mineral assemblages are characterized by zircon, rutile, and tourmaline with moderate ZTR indices, supporting derivation from felsic igneous and high-grade metamorphic basement sources. Geochemical signatures, including high SiO₂ contents, felsic-dominated trace-element ratios, and elevated CIA, CIW, and PIA values, indicate moderate to intense chemical weathering of granitic and gneissic source rocks. Tectonic discrimination diagrams consistently place the sandstones within the continental rift field, confirming syn-rift sedimentation controlled by fault-related subsidence and basement uplift. Collectively, the Bima Sandstone at Hinna records a multi-cycle, syn-rift braided fluvial succession deposited in a fault-controlled intracontinental rift basin, refining the tectono-sedimentary evolution of the Gongola Basin and contributing to improved basin analysis and reservoir characterization in the Upper Benue Trough.