An integrated geophysical and geochemical analysis was carried out on sediments of the Yolde formation in the Upper Benue trough. The sedimentology of the study area described is based on drill core samples that showed dominantly Laterite, Clay, and Coal with intercalations of cobblestones, shale, sandstone, coals and silt. A seismic refraction survey was conducted, processed and interpreted to determine the velocity and variability of the weathering layer across the study area. The weathering depth in the study area range from 6.10m to 29.90m with an average of 16.50m which is indicative of intense weathering in the area, although this variability in depth was found to be influenced by the heterogeneous nature of the lithology and elevation in the study area as obtained from the Up-hole Seismic Refraction survey. From the results of the TOC analysis, 57% of the samples are indicative of high organic matter content while only about 43% fall short of the minimum value of 1.0wt% for a good source rock. Meanwhile the coal samples were found to have the highest TOC values of 58.10wt% to 64.06wt%. Most of the samples were also found to be of kerogen types III & IV and are generally immature as shown by the plots from results of the Rock Eval analysis. The graph of S2 versus TOC showed that kerogen type, mainly types III and IV, which are less than half of the samples indicating poor hydrocarbon potential for gas, and a reasonable number of samples has no possibility of oil or gas. Given the low Sulphur content, anoxia and euxinic conditions are ruled out for this period of marine incursion during the Cenomanian, indicating unfavorable conditions for organic matter preservation showing poor hydrocarbon potentiality.
Key words: Yolde formation, Northern Benue Trough, shales, Hydrocarbon generation potential, Weathering layer, Cenomanian, Total Organic carbon, Rock-eval pyrolysis
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