The oil shale deposit in the Abakaliki anticlinorium has not been demarcated. The present study focused on the age, correlation and depositional environment of the oil shale using abundance, planktonic/benthonic ratio and species diversity of foraminiferal and ostracod assemblages. The result shows that three prominent peaks or biozones namely 1 st , 2 nd and 3 rd were recognized. The 1 st biozone showed that Praeglobotrucana and Guembelitria are the dominant species and ranged from Albian to . The 2 nd biozone indicated that Hedbergella and Heterohelix are the dominant species, and ranged from Upper Cenomanian to Early Turonian (92-95 my). The 3 rd biozone showed that Heterohelicids are the dominant species and ranged from Middle Turonian to . The 1 st , 2 nd , and 3 rd biozones correspond to the deposition of Asu River Group (Abakaliki Shale), Eze-Aku Formation and Awgu Formation respectively. The 2 nd peak is bimodal and has the highest frequency and this supports the maximum transgression occurring at the Cenomanian-Turonian boundary event (ocean anoxic event). The oil shale is deposited in outer shelf to bathyal environment and ranged from Upper Cenomanian to Early Turonian age and belongs to the Eze-Aku Formation.
An extensive geological mapping and geochemical studies of the oil shale deposit in the Abakaliki Anticlinorium, southeastern Nigeria were carried out to determine its areal extent, reserve estimate, recovery techniques and possible environmental impacts. The total area of the exploitable zones that is characterized by shale alternating with marl has been calculated to be 72.7 km 2 by placing a 1,000 m by 1,000 m grid outlay on the mapped sections. Using an exploitable thickness of 34 m and an areal extent of 72.7 km 2 , the oil shale reserve estimate is 5.76 ! 10 9 tonnes. Moreover, using an average Fischer Assay yield value of 56.35 litre/tonne, the recoverable hydrocarbon reserve estimate is 1.7 ! 10 9 barrels. Retorting recovery method is suggested for exploitation of local oil shale because of shallow upper soil and a relatively cheap cost of establishments. Low concentration of sulphur (between 0.33 and 0.74%) and trace elements such as Ba, Cd, Cu, Cr, Ni, Pb and Zn supports the economic viability of oil shale as refinery feedstock.
The usefulness of limestone as an industrial raw material is dependent on the level of its purity, largely controlled by diagenesis and the depositional setting. Limestone samples (83) obtained from the Ewekoro Formation exposed in quarry sections at Shagamu were analyzed using X-Ray Fluorescence spectrometry (XRF). A geochemical characterization of result was done to evaluate the purity levels and the implications on provenance, diagenesis, and depositional setting of the limestone. Five limestone beds from quarry sections (15 locations) were logged. Beds "E", "D", "C", "B", and "A" comprised sandy algal in sparry calcite cement, sandy biomicrite, algal biomicrite, sandy algal biomicrite, and the intra-sparite facies respectively.
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