DETERMINTION OF SEDIMENTARY THICKNESS IN LAFIA AND ENVIRONS, NORTH CENTRAL NIGERIA USING AEROMAGNETIC DATA

ABSTRACT The aim of this study is to define the sedimentary thickness in Lafia and environs using aeromagnetic data. The areal extent of the study area is 3025 km2. The methodology involves the use of aeromagnetic sheet 231 collected from NGSA with latitude of 8000lN to 8030lN and longitude of 8030lE to 9000lE, which were subjected to analysis using Peter’s Half Slope method of depth calculation. Both 2D and 3D earth model were produced using Surfer 32 contouring software. Also, the rose diagram of the study area was generated using GeoRose software. The qualitative interpretation of the magnetic maps (total aeromagnetic intensity and residual anomaly maps) reveals magnetic intensity ranging from 7985nT to 8090nT and 15nT to 90nT in the research area. The magnetic maps also reveal sparse contours around the northwestern and southwestern parts of the area suggesting high depth to magnetic sources. The movement of contours away from each other at the northeastern part of the residual map revealed signs of faulting inside the research area. The analytical map Rose diagram results show that the structural features/lineaments trend prominently in the northeast – southwest (NE-SW) direction whereas, the minor features trend in east-west (E-W) and southeast – northwest (NW-SE) patterns. The Peter's half slope method for estimating depth revealed two depth sources in the study: deeper magnetic sources which range from 2.20 km to 4.24km, whereas the shallow magnetic source ranges between 0.40km and 2.2km. The depths to the basement were deeper in the northwestern and southwestern section of the research area and shallower in the southeastern sections. Based on the result obtained, the sedimentary thickness which is above 2.1 shows there’s a possibility of sediments favoring hydrocarbon accumulation and other resources, provided that other factors for petroleum generation are available which conforms with Chinwuko (2023).