Evaluation of Presence of Quicklime (CaO) in Ohafia-Arochukwu Areas of Nsukka Formation, Afikpo Basin, Southeastern Nigeria

Abstract

The co-ordinates of the area studied are within latitudes 5^o29ˈ to 5^o51ˈN and longitudes 7^o29ˈ to 8^o00ˈE. The Nsukka Formation in the studied area consists of two facies associations; limestone-shale and cross bedded sandstone. The Limestone-shale facies association consists of the following lithofacies; rippled clayey sandstone, carbonaceous shale, heterolithic sandstone-shale, laminated grey shale, fossiliferous limestone, Fine grained sandstone, Silty shale, Medium grained sandstone and carbonaceous sandstone. The cross bedded sandstone facies association consists of only cross bedded sandstone. Representative samples of these rocks from Ohafia area were collected and stored in a polythene bag for further investigations. XRF analyses were carried out on these rock samples. The XRF oxide content of elements in sample OHA 1 of original rock was found to be CaO (76.00), Fe₂O₃ (8.35), SiO₂ (7.13), Al₂O₃ (2.46), SO₃ (2.29) and MgO (1.81) with other oxides in minor quantities. The shale-limestone lithofacies of OHA 2 of the same rock showed CaO (85.90), SiO₂ (5.13), MgO (2.56), Al₂O₃ (1.80), SO₃ (1.71), Fe₂O₃ (1.20) and P₂O₅ (1.02) with other oxides in minor quantities. OHA 3 of cross-bedded sandstone lithofacies contains SiO₂ (52.70), Fe₂O₃ (14.10), Al₂O₃ (14.50), MgO (3.74), CaO (9.00), TiO₂ (2.54), K₂O (1.41) and Cl (0.12) with other oxides in minor quantities. For OHA 4 through the XRF indicates Chloride (Cl), CaO and SiO₂ contains 79.60%, 0.58% and 3.52%. The samples showed that major component were SiO₂, Al₂O₃, Fe₂O₃, CaO, MgO and TiO₂. The presence of CaO was determined to be deposited on the surface of debris of rocks in the area. It was observed that the occurrence of CaO is amorphous in nature and not crystalline.