New insights into crustal and geological structures beneath the Southern Benue trough of Nigeria and parts of Cameroon Volcanic Line from tailored gravity data

We utilized a high-resolution tailored gravity dataset to investigate the geological structure beneath the Southern Benue Trough of Nigeria and along the Cameroon Volcanic Line (CVL). The tailored gravity data was obtained by applying a stochastic combination technique to integrate global gravity field model, terrestrial gravity data, and residual gravity data over the study area. We then carried out gravity techniques to compile the Bouguer gravity map and to estimate the crustal thickness. To obtain suitable estimates of the reference depth and density contrast of the Moho interface, we fitted the gravimetrically determined Moho geometry to the seismic estimates by minimizing the Root-Mean-Square of their differences. A minimum RMS of 3.6 km at a reference depth of 26 km and a density contrast of 450 kgm⁻³ was achieved over the study area. Our results reveal a dense magmatic feature criss-crossing the central portion of the study area. This phenomenon led to a thinning of the crust and formation of various geological structures, mainly at the southern end. We could see a very thick sedimentary cover within some of these structures possibly occasioned by compressional and extensional tectonic forces acting at the southwest end. Our study reveals that these compacted sedimentary covers could be important habitats for mineralization. We have also been able to refine and depict the lateral extent of the crustal architecture at a fine scale using our tailored gravity dataset. We concluded that the tectonic events beneath the study area are complex and point to several geophysical factors earlier revealed in published studies. However, a narrowing of two or more conjugate plates (margins) propelled by an upward force may have primarily led to the upward displacement of some of the magmas in-between those plates forming the intrusive rocks.