The study area lies in the western flank of the Abakaliki anticlinorium and Southern part of the Benue Tough.
This Trough is occupied by Albian and Upper Cretaceous sediments that has been compressionally folded (Wright, 1976).
The sediments of the area belong to the Eze-Aku formation of Cretaceous age. They were deposited in the Turonian Sea and lie unconformably on ASU-River Group sediments of Albian age. Turonian heralded an extensive transgression phase that led to the deposition of Eze-Aku formation (Reyment, 1965). The transgression was traced to be the result of final separation of South America and Africa plates. It brought in the second sedimentary cycle of Murat (1972), the first being the Albian and hence the history of Cretaceous sediments of south eastern Nigeria began.
Generally, this formation consists of beds of rapidly changing lithofacies including shale and limestone with shallow marine fauna such as ammonites, gastropods, and foraminifera’s that helped in geological dating of sediments.
The Santonian deformational episode that resulted in the folding and uplift of the NE-SW trending Abakaliki anticlinorium’s led to the exposure and erosion of Coniacian, Turonian and Albian sediments. After the epeirogeny Campano- Maastrichtian transgression led to deposition of late Cretaceous sediments and this account for the absence of Coniacian sediments in the western flank of the Abakaliki anticlinorium. Jointing of rocks in the area is an evidence of Santonian deformation episode.
SUMMARY AND CONCLUSION ON GEOLOGICAL HISTORY
Turonian stage sediments occupy the study area. The sediments consist of shale and limestone facies of the Eze-Aku formation. The gradation of limestone from biosparites to biomicrites limestone was as the result of high energy to low energy activity in the deposition of the sediments. The formation was deposited during the transgression of Turonian stage in a subtidal shelf sea agitated by storm waves that transported sediments and fossils from near shore into a quiet shelf.
This environment was conducive for distribution of fossils such as Ammonites, gastropods, pelecypod and some species of micro fossils found in the Eze-Aku formation. Fossil shells were broken probably during transport or as a result of predation.
Santonian tectonism brought about jointing in the rocks of the study area.
The petrographic study of the thin section slides shows that the limestone has a high percentage content of calcite, which indicates that the limestone of the study area is very good for cement production.
The exploitation of this economic mineral in the study area has greatly impaired the environment. Around the quarry sites, landscape vision is greatly impaired and land for agricultural purposes is drastically limited. In addition, pollution of all kinds arising from the quarry dump and the abandoned equipments are of great concern.
The underlying lithologies of the area are impervious thereby yielding little or no water and have resulted to water scarcity in the area. Moreover, some available water resources around the mining area suffers contamination from the activities of the miners
This project thesis is invaluable to so many individual researches, corporate organizations, and the government. As such, I am obliged to recommend as follows:
- A research on geochemical analysis of the Nkalagu limestone should be vividly carried out in order to determine the major and trace element concentration.
- Government should do all things within their reach to re-activate the Nigeria Cement Company (NIGERCEM) to its full operational capacity. This will help to reduce the rate of unemployment in the country and as well reduce the high rate of social unrest as the youth of the area will be engaged in useful activities.
- I also recommend that government should enact laws for effective exploitation of limestone in the study area and also enact laws for site reclamation after mining operation in order to reduce the effect of mining on the land use.
- I also recommend that there is need for effective distribution of pipe-borne water or siting of more water boreholes to the people around the study area in order to help alleviate the problem of water scarcity and reduce the incidence of some water – borne diseases in the area.