On the Use of Linear Trend Analysis in Removing Regional Gradient from Ground Magnetic Data for Qualitative Interpretation

摘要

Advances in technique development and data interpretation have greatly improved our ability to visualize the Earth subsurface. Total field magnetic data on the Olugere Area of Ijero Ekiti, Southwestern, Nigeria were acquired using the ground based magnetic technique with the aid of portable proton precession magnetometer G-856AX which implores total components of the ground magnetic anomaly data running through six profile lines. A total of six geophysical traverses, numbering aa to ff, were established in an E-W direction in the study area. The acquired total magnetic intensity (TMI) data were corrected for drift; the derived residual anomaly, which involves the removal of the regional gradient from the observed data from the field of linear trend analysis, was presented as profiles and maps. The residual magnetic values varied between a minimum negative peak value of about -223.1nT and a maximum positive peak value of about 536.7nT. Qualitative interpretation of the ground magnetic maps and profiles were adopted with an intention of determining the geologic structures that are suitable for mineral potential, ground water accumulation and establishing the competence of the survey area in hosting high rise structure and industrial site. Our results have demonstrated that careful analysis of magnetic data can delineate with fair to good precision the geological structures of the subsurface, which gives vital information about the mineral potential, ground water accumulation and the ability of the study area to hold high rise building.