Petrographic Composition of the Coal Within the Benue Trough, Nigeria, With a Consideration of the Paleodepositional Setting

The petrographic composition of coals hosted in the Benue Trough, Nigeria are presented and discussed in terms of paleodepositional setting that influenced the coal-bearing formations. The Benue Trough is a failed arm of the triple ‘RRr’ junction of an inland sedimentary basin that extends in a NE-SW direction from the Gulf of Guinea in the south, to the Chad Basin in the north. A total of twenty-nine (29) coal samples were obtained from 19 coal localities in the Upper (UBT), Middle (MBT), and Lower Benue Trough (LBT). The proximate data indicates the coal samples have a high volatile matter content, low ash yield, and high calorific value (24.82 MJ/Kg, on average). The sulphur values are generally low (average of 0.94 %). The coal samples are generally high in vitrinite, with an average of 59.3% by volume (mineral-matter free). Variation was noted in the inertinite content for the three sub-region samples. Liptinite macerals were not commonly observed in the studied samples and are absent in the MBT samples. The MBT coal samples reported a higher gelification index than the UBT and the LBT samples. Comparison of the array of coal facies models show the MBT samples are different from the UBT and LBT samples, concurring with the characterisation data. In view of the modified equations and the plots used, interpreting depositional environment accurately from just a single model is quite challenging.

Chemical Characteristics and Assessment of Groundwater Quality Between Two Geological Group of the Lower Benue Trough ,Nigeria

Hydrochemical studies was carried out within two geological groups of the Albian to Turonian in age to evaluate factors that influences hydrochemistry of groundwater. To achieve this, 30 groundwater samples were collected. Parameters such as pH, Electrical Conductivity (Ec), Total Dissolved Solids (TDS), Total Hardness (TH) and hydrochemical characteristics (Na2+, K+, Ca2+, Mg2+, HCO3¯, NO3¯, Cl¯, CO23¯ and SO42¯) of groundwater were determined. Findings revealed that pH value for Asu River Group ranges from 5.3 to 7.5, and that of Eze Aku Group ranges from 4.1 to 7.9. It was observed that areas around the mines had low pH value. Analyzed results that was obtained were interpreted using various hydrogeochemical models. Parson plots showed that groundwater within the two geological groups fell within Ca˗Mg˗SO4 and Ca˗Mg˗Cl. Results from End˗member plots revealed that 96 % groundwater samples analyzed were categorize under carbonate weathering, 4 % fell under silicate weathering. Deductions from Gibbs revealed that interactions between groundwater and surrounding host rocks is the major processes responsible for chemical characteristics of groundwater, Diamond field plots further suggested that groundwater from the two geological group were categorized to be high in Ca + Mg & SO4 + Cl, plot of Ca2+/(HCO3¯ + SO42¯) against Na+/Cl¯ revealed that groundwater were considered to be within natural state for the two group. Plot of TDS against TH showed that groundwater was classified to be soft fresh water. The study revealed there was no significant difference between factors that influences groundwater within the two geological group.