CHEMOSTRATIGRAPHY AND PALEOENVIRONMENTAL EVOLUTION OF THE LATE MAASTRICHTIAN GOMBE FORMATION ALONG GABUKKA STREAM SECTION, GONGOLA SUB-BASIN NORTHERN BENUE TROUGH, NORTHEASTERN NIGERIA

Abstract

The Late Maastrichtian sedimentary succession of the Gombe Formation in the Gongola Sub
basin of the Benue Trough preserves a high-resolution record of paleoenvironmental 
fluctuations immediately preceding the terminal Cretaceous. This study integrates 
chemostratigraphic analysis with paleoenvironmental reconstruction of the Gombe Formation 
exposed along the Gabukka Stream section, northeastern Nigeria. Systematic sampling of 
mudstone facies was conducted across measured stratigraphic intervals, and geochemical 
characterization was performed using X-ray fluorescence (XRF) to quantify major and trace 
element compositions. Key elemental ratios, including Ti/Al, K/Al, Si/Al, Fe/Mn, and Sr/Ca, 
were employed as proxies for detrital influx, sediment maturity, redox conditions, and marine 
influence. The results delineate three distinct chemostratigraphic zones characterized by 
systematic vertical geochemical variability. Elevated Ti/Al and K/Al ratios define intervals of 
intensified terrigenous input, likely linked to enhanced continental weathering and sediment 
supply. Conversely, fluctuations in Fe/Mn ratios indicate variable bottom-water redox 
conditions, reflecting shifts between relatively oxic and suboxic depositional environments. 
Trends in Sr/Ca ratios further suggest episodic marine incursions and variations in salinity 
regimes. Collectively, the geochemical signatures document a progressive paleoenvironmental 
transition from proximal, high-energy siliciclastic settings dominated by continental input to 
more distal, marine-influenced conditions during the Late Maastrichtian. This transition is 
consistent with regional transgressive trends recognized within the northern Benue Trough. 
The study refines the chemostratigraphic framework of the Gombe Formation and provides 
critical insights into sedimentary processes, basin dynamics, and paleoenvironmental evolution 
during the latest Cretaceous, with implications for regional stratigraphic correlation and basin 
analysis.