Authors : A.A. Okiwelu , E.E. Okwueze and V.I. Obianwu
Abstract: Magnetization due to remanence of magnetic sources in the earth�s field in equatorial belt (magnetic equator) may be analysed using simple models. The models are magnetic signatures with low in the north flanked by magnetic high in the south (point pole) and isolated magnetic high (point dipole). The model is based on the effect of dyke magnetized due to remanence in the earth�s field because of the suitability of dyke-like bodies in the most geological situations. In the model to obtain the resolved direction of the remanent component (Ir), (amplitude ratio), Fmax (maximum amplitude), Fmin (minimum amplitude) and (index parameter) must be evaluated. To test the applicability of the models, aeromagnetic data from part of Niger Delta basin of Nigeria and the adjacent geological province (Calabar Flank) were analysed. The result show that the resolved direction of remanent component of the magnetic field is in the neighbourhood of 260�/-100�. This result has application in paleomagnetic study. From the magnetic data sets, detrital and thermal remanent magnetization were inferred. The detrital remanence is probably due to great thickness of sedimentation in the delta while the source of the thermal remanence in the adjacent Calabar Flank suggest wide spread igneous intrusions which has subjected the Flank to high temperature. The intrusives are identified in the magnetic data by linearments. The linearment indicate structural features that have controlled the tectonic expression of the Flank. Therefore, correlation can be established between remanence, tectonism and paleomagnetism.
A.A. Okiwelu , E.E. Okwueze and V.I. Obianwu , 2008. Simple Models for the Interpretation of Magnetic Anomalies Due to Remanence in Magnetic Equator. Online Journal of Earth Sciences, 2: 90-98.