Application of Gravity and Magnetic Data for Tectonic Framework Analysis of the Sokoto Basin, North West Nigeria

The Sokoto Basin, occupying the northwestern corner of Nigeria, is the westernmost expression of the Iullemmeden Basin that extends into Niger, Mali, and Algeria, and its tectonic framework has been only broadly characterised through regional geological reconnaissance without the benefit of modern geophysical data integration. This study applies advanced processing and modelling of available gravity and aeromagnetic datasets to define the tectonic architecture of the Sokoto Basin, including intra-basin structures, basement depth, and sediment thickness variations. Regional Bouguer anomaly data were filtered to separate long-wavelength lithospheric signals from basin-scale structural signatures. Residual Bouguer anomalies were modelled along five profiles spanning the basin in NE-SW and NW-SE directions to estimate basin geometry and the density contrast between basement and basin fill. Aeromagnetic data processed using the analytic signal and tilt angle derivative reveal a set of NNE-trending positive anomalies within the basin interpreted as buried basement ridges, in addition to several circular anomalies attributed to mafic intrusions within the sedimentary sequence. A revised basement depth map constructed from the integrated modelling shows a major depocentre of approximately 1,200 metres in the central Sokoto area, bounded to the north and south by fault-controlled basement highs. The tectonic framework is interpreted in the context of Pan-African and Cretaceous reactivation events documented in regional geological literature. Keywords: Sokoto Basin, gravity, aeromagnetic, tectonic framework, basement depth