The Benue Trough of Nigeria has been affected by at least two episodes of deformation in the Cenomanian and Santonian times. The deformations generated NE-SW trending structural features, which accommodated
massive igneous activities in the Trough. The Lokpaukwu–Uturu–Ishiagu magmatic belt of the Lower Benue Trough is an example of these structurally controlled igneous intrusions. The igneous rocks are predominantly intermediate to basic in character, rich in plagioclase and ferromagnesian minerals and have impacted high maturity on the source sediments due to thermal effect. Total organic carbon contents of the mudrock inclusions in the pyroclastics range from 0.60%wt – 0.86%wt. It is apparent that prior to the
eruption, an initial shaly source rock with higher organic carbon content was cooked during the eruption, thereby reducing the source quality of the rocks. Thus, heat from the igneous intrusions raised the temperature of the source rocks above the liquid oil window limit, and thus inhibited the preservation of the essential constituents of petroleum in the shales within the Lower Benue
Trough
