Lineament studies of rocks in Omifunfun area, southwestern Nigeria: Remote sensing and petrologic observations

Abstract

Omifunfun area is situated in the southern part of Ife-Ilesa Schist Belt of the basement complex of southwestern Nigeria. The study area is traversed by the Ifewara Fault Zone which divides the area into east-west with contrasting lithologies that have been variously mylonitized. To the east, is quartzite and to the west migmatite gneiss which are intruded by prophyritic granites. The objective of this study is to delineate deformation linear structures from Landsat imageries over the study area, and attempt to correlate the information with microtectonic structures and field observations with the aim of better understanding the geologic terrain. Lineaments were extracted from Landsat images covering Omifunfun area. The analysis of these lineaments indicates low density in three prominentorientations corresponding to 0000–0350 and 0600–0900 with minor northwest-southeast structures. The most prominent of these directions is the 0000–0350 which incidentally include mylonite and mineral lineations within the Ifewara Fault system. Microtectonic observations reveal analogous results with three prominent foliation directions. The dominant one strikes in the same direction with the same Ifewara mylonitic foliation. These directions correspond to two major planar surfaces S1 and S2 and were respectively produced during two episodes of deformation (D1 andD2).KEYWORDS: Ifewara Fault Zone, Lineament, Microtectonic Structures, Mylonitization, Remote Sensing