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This study interprets gravity data in parts of southeastern Nigeria using spectral analysis and 2D modeling. The study area is bounded by Latitudes 5°N 30' to 6°N 30' and Longitudes 7°E 0' to 8°E 0'. The Bouguer gravity data was obtained from the Nigerian Geological Survey Agency (NGSA) in Geosoft grid file format. The study uses the spectral analysis method and 2D modeling with GM SYS to estimate the average depth of the sedimentary strata and the basement from the Bouguer anomaly map. The data sets cover the southern part of the Anambra basin and the northern Niger Delta complex. Regional-residual separation was applied to the Bouguer gravity data through the polynomial fitting of the first degree. This gave rise to the residual and regional maps. Further filtering actions accentuated the subtlest anomalies peculiar to the study area. Spectral analysis results reveal two depth models: deep source (D1) and shallow source (D2). The deep source represents depths within the basementrelated sources, while the Shallow source is associated with shallow-related gravity sources. D1 varies from 1.50 km to 4.02 km with an average value of 2.95 km, while D2 varies from 1.91 km to 0.514 km with an average value of 1.50 km. The thickest depth of the Modelled cross-section is at about 6845.62 m, which is within the tertiary recent sediment with clayey sands and shale extending beyond the study area. The average or actual sedimentary thickness of 2.95 km suggests that the area will be plausible for hydrocarbon exploration. The thickest sedimentary cover represents density variation in sedimentary rock of the basin, which occurs at the southern part of block 4 (Okigwe). [ABSTRACT FROM AUTHOR]

The Asu River Group Shale in the Oshiri area was evaluated using ground magnetic and geoelectrical methods within existing mine. Some exploration programs in the area have resulted to failure due to the fact that project managers have not fully understood the use and importance of geophysics in enhancing the search for mineral deposits. The aim of the study was to delineate the sulphide deposits using ground magnetics and geoelectrical methods. Result of the ground magnetic survey delineated some shallow tectonic structures like fractures and faults which are capable of hosting metallic sulphide deposits. The residual magnetic intensity of the study area indicates very low magnetic field intensities around the central and southern portions of the study area. These low values indicate absence of magnetite in the near surface materials as suggested by previous studies in the area, but could be referred to as zones with shallow tectonic structures which could be faults and/or fractures capable of housing sulphide deposits. The orebearing veins within the sedimentary rocks have susceptibilities of = -1.8 nT. The low, negative residual susceptibility zone in the southeastern portion of the study area was targeted for the induced polarization IP and electrical resistivity tomography. Four traverses of induced polarization IP and resistivity surveys were carried out with all the profile lines were in the NE-SW direction. Isolated chargeable bodies with values greater than 340msec and a correspondingly low resistivity values (10Om-50Om), were encountered across some of these profiles. This zone may represent zones with sulphide mineralization. These identified chargeable bodies occur at approximate depth and width range of between 25-30m and 50-70m respectively. The 1D stratigraphic models reveal an average thickness estimate of 11.0m. Using scalar geometric approach, an estimate of 103,513.75tonnes was obtained, representing a relatively economically viable quantity and a worthy target for investors. [ABSTRACT FROM AUTHOR]