Abstract
The Okemesi fold belt is an antiformal structure made up of massive quartzite and schist in southwestern Nigeria was investigated in order to quantify the local principal stress orientations and present day geometry of the rocks affected. This study describes both the past and active deformation and regional structural development. For the local stress orientation, inversion of seventy-five microtectonc data collected at nine sites, where a total of four local stress states were revealed. The criteria used to establish the local paleostress fields include cross-cutting striations, sigmodal tension gashes, micro faults, conjugate shear fractures, joints, pre and post folding stress state. Four principal deformation structures at both local and regional scale have been recognized: (1) sheared and folded structures (2) thrust fault (3) normal fault and (4) strike-slip fault. It indicates that the Okemesi fold belt of covers area of about 132 Km experienced a complex history of tectonics initiated by variable periods of transpression, stress regimes of contraction, shearing and is currently undergoing extension. The paleostress analysis shows: (1) compression in an NNE direction as inferred from both the fracturing and strike-slip faults; and (2) the presence of N-S and E-W extension billeted by normal faulting. *This study describes both the past and active deformation and regional structural evolution of the Okemesi belt and Ifewara fault from both field mapping and geometric analysis of mega structures.
Publication Info:
Author: Bamisaiye, O.A.
Volume: 57
Issue: September
Published By: Journal of Mining and Geology, 2024-09-01