Mapping of subsurface geological structures and depth to the top of magnetic basement in Bornu Basin and its environs, NE Nigeria, for possible hydrocarbon presence

Abstract

The present study aims to provide a new insight into the subsurface geological structures and the depth estimates of the sedi ments aiding hydrocarbon maturation and accumulation within the Bornu Basin, NE Nigeria, via 2D magnetic structural and depth modelling. The total magnetic feld anomaly map was reduced to the magnetic equator (RTE-TMI) to align the mag netic anomalies over their causative bodies. The resulting RTE-TMI map and the frst- and second-order vertical derivative maps distinctively mapped the intra-sedimentary volcanic rocks and shallow to deep-seated structures. On the other hand, the source parameter imaging (SPI) and 2D depth constrained magnetic anomaly models determined the depths of these geologic features. The dominant structures within the study area trend NE-SW, NNE-SSW, ENE-WSW, ESE-WNW and NW–SE. SPI model indicated that the thickness of sedimentary beds ranges from 1.02 to 5.55 km, with a maximum thickness of≥3.0 km obtained in the central, central eastern, southwestern, northeastern, eastern and western parts of the study area, corresponding to Gubio, Gadayi, Nafada, Marte, Dikwa and Gabdam, respectively. The 2D magnetic depth models from the seven profles taken on the RTE-TMI map in N-S and SE-NW across signifcant anomalies revealed lithological boundaries and the thickness of sediments ranging from 1.0 km to a maximum thickness of 11.5 km. The thickness of sediments of 3.0 to 11.5 km is sufcient for hydrocarbon maturation and accumulation in Bornu Basin (a typical rift basin), with the deline ated embedded structures serving as migratory paths or traps for the generated hydrocarbons.