In this current work, we aim to delineate the subsurface structural trends, determine the depth to basement surface, and provide an illustrative 3D model for its subsurface structure. Four digitized aeromagnetic maps were acquired from the Nigerian Geological Survey Agency, Abuja. The total field aeromagnetic anomalies over Koton Karifi and adjoining areas have been evaluated. In order to map the subsurface structures and estimate the depth to basement surface the spectral analysis method was applied. To achieve such goals, a detailed analysis of the aeromagnetic data for the study area was performed. 2D interpretation was carried out for the aeromagnetic data. The processes used include contouring of the Total Magnetic Intensity (TMI) data, separation of regional and residual anomalies, structural detection methods such as analytic signal, vertical derivatives, and magnetic lineament mapping were used to map the contacts and faults within the study area. The first vertical derivative and the magnetic lineament maps show major geologic lineaments trending in East-West with minor ones trending Northeast-Southwest. In the south-eastern part of the study area, there is a dome-shaped linear feature. The result obtained using the spectral analysis method reveals two source depth models. The depths to deeper magnetic sources range from 2.81 km to 3.24 km with an average depth of 2.90 km. The deeper magnetic source bodies are identified with the magnetic basement. The shallower magnetic sources which range from 0.45 km to 1.81 km with an average depth of 1.13 km could be attributed to near surface magnetic sources which are magnetic rocks that intruded into the sedimentary formations or magnetised bodies within the sedimentary cover. Based on the sedimentary thickness range of 0.45 to 3.24 km, there is an indication that the possibility of hydrocarbon generation in the study area is feasible.

The aeromagnetic data of Monguno area northeastern Nigeria have been used to estimate Curie point depth, geothermal gradients and heat flow using spectral analysis. These geothermal parameters were subsequently employed to identify areas of geothermal resources. First order polynomial fitting was applied in Regional-residual separation. The Curie point depth obtained in this area ranges from 10.318 to 24.476 km with an average of 13.387 km, the geothermal gradient of the area varies from 23.697 to 56.212°C /km, with an average of 46.195°C /km, while the heat flow ranges from 59.242 to 136.176 mWm-2, with an average value of about 112.364 mWm-2. It was also observed that the deepest Curie depth in the area is identified in the south, while the shallow depth is located in the northeast and spread toward the southwest. On the other hand, the highest geothermal gradient in the area is identified in the northern part of Moguno, while in the south,                    the lowest, geothermal gradient is located. The highest heat flow in the area is seen in the south-west and north-east, while the lowest heat flow is observed in the south. The high heat flow and geothermal gradient in the area show that geothermal energy could be found in Monguno region of the northeastern Nigeria.

Aeromagnetic and aerogravity data covering Masu area, which lies within latitudes 12°00′ to 13°00′ North and longitudes 12°30′ to 14°00′ East in Nigerian sector of Chad Basin have been interpreted qualitatively and quantitatively. Regionalresidual separation was carried out by applying polynomial fitting (first order), which was fitted by least square method. First order was used because it is the best regional fit for our data as it reflected the available geological information of the area. The residual values of both magnetic and Bouguer anomalies obtained were used to produce the residual magnetic intensity and residual gravity maps respectively. These maps show intrusive basement rocks in the eastern part of Masu. The forward and inverse of aeromagnetic data modeling estimated basement depths for profiles P1 and P2 were 4300 and 1195 m, with respective magnetic susceptibility values of 0.0003 and 0.0250, which indicate minerals like limestone and marble. Similarly, the estimated basement depths from the forward and inverse of aerogravity data modeling are 6524 and 4312 m for P1 and P2 with density contrasts of 0.72 and 0.255 g/cm 3 . The results from this work indicate that the area has some geologic features suitable for hydrocarbon and mineral deposits. Hence, further geophysical researches need to be carried out to ascertain the type of minerals existing in the area.Keywords Aeromagnetic and aerogravity data · Masu · Nigeria · Chad basin · Hydrocarbon potentials · Mineral deposit · Forward and inverse modeling

The incessant power outage and power rationing in Nigeria has affected the economic development, hence the need to seek for other sources of electricity generation such as geothermal energy which is environmentally friendly and renewable. The wide range of geologic formations in the north-eastern Nigeria provides an avenue for exploration of geothermal energy. Hence, this work carries out an investigation of Curie point depth, geothermal gradient as well as heat flow in Masu, which is located within Nigerian sector of Chad Basin (lat. 12°00' to 13°00' N and long. 12°30' to 14°00' E) using spectral analysis. Application of minimum curvature in gridding the total magnetic field intensity data was done using the Oasis Montaj 6.4.2 software. First order polynomial fitting was applied in Regional-residual separation. The Curie point depth obtained ranges from 12.233 to 16.184 km with an average of 13.993 km, the geothermal gradient of the area varies from 35.838 to 47.413°C /km, with an average of 41.821°C /km, while the heat flow ranges from 89 to 117.80 mWm -2 , with an average of 104.551 mWm -2 . The 2D contour maps reveal that the Curie point depth is lowest in the southeast and increases towards the northwest, while the geothermal gradient and heat flow on the other hand are highest in the southeast and decrease towards northwest. The high geothermal gradient and heat flow values in the area are indications that the area might be suitable for geothermal energy generation as an alternative power supply in the area and in the country at large.