Interpretation of High Resolution Aeromagnetic Data Over Okigwe And Some Adjoining Areas, South Eastern Nigeria

Abstract

Digitized high resolution total field aeromagnetic data over Okigwe and environ (Sheet 312) was interpreted using the standard 3-D Euler de-convolution and spectral analysis in order to determine depth to the magnetic basement, delineate the basement topography and relief, and delineate the trend of the structural features associated with the basin. The aeromagnetic data were subjected to various data enhancement and transformation routines using the Geosoft Oasis MontajTM software. Results of the study revealed that the dominant structural trend of the study area is in the northeast-southwest (NE-SW) direction. Other lineament trend is in the northwest -southeast (NW-SE) direction. The Results of the 2-D spectral analysis revealed a two layer depth model. The shallower magnetic source (D1) has an average depth of 0.5338 km, while the deeper magnetic source bodies (D2) has an average depth of 2.2048 km. The shallower magnetic anomalies is as a result of basement rocks which intruded into the sedimentary rocks while, the deeper magnetic anomalies is associated with intra-basement discontinuities like faults. The windowed 3-D Euler de-convolution for the anomalous bodies using structural index (SI) of 0.0, 1.0, 2.0 and 3.0 shows the presence of intrusive bodies in the form of contacts, dykes and sills, vertical pipes and spheres which are located at various depths ranging from 0.25 km to 3.0 km in the northern part of the study area.