Multi-scale analysis and modelling of aeromagnetic data over the Betare-Oya area in eastern Cameroon, for structural evidence investigations

This study was carried out in the Lom series in Cameroon, at the border with Central African Republic, located between the latitudes 5 degrees 30'-6 degrees N and the longitudes 13 degrees 30'-14 degrees 45' E. A multi-scale analysis of aeromagnetic data combining tilt derivative, Euler deconvolution, upward continuation, and 2.75D modelling was used. The following conclusions were drawn. (1) Several major families of faults were mapped. Their orientations are ENE-WSW, E-W, NW-SE, and N-S with a NE-SW prevalence. The latter are predominantly sub-vertical with NW and SW dips and appear to be prospective for future mining investigations. (2) The evidence of compression, folding, and shearing axis was concluded from superposition of null contours of the tilt derivative and Euler deconvolution. The principal evidence of the local tectonics was due to several deformation episodes (D1, D2, and D4) associated with NE-SW, E-W, and NW-SE events, respectively. (3) Depths of interpreted faults range from 1000 to 3400 m. (4) Several linear structures correlating with known mylonitic veins were identified. These are associated with the Lom faults and represent the contacts between the Lom series and the granito-gneissic rocks; we concluded the intense folding was caused by senestral and dextral NE-SW and NW-SE stumps. (5) We propose a structural model of the top of the crust (schists, gneisses, granites) that delineates principal intrusions (porphyroid granite, garnet gneiss, syenites, micaschists, graphite, and garnet gneiss) responsible for the observed anomalies. The 2.75D modelling re- vealed many faults with a depth greater than 1200m and confirmed the observations from reduced-to-Equator total magnetic intensity (RTE-TMI), tilt derivative, and Euler deconvolution. (6) We developed a lithologic profile of the BetareOya basin.

Automated summary

This study conducted in the Lom series in Cameroon revealed major fault families, discussed depths of interpreted faults, local tectonic features, and deep structural models. Modeling of the crust structure revealed fault distribution and deep anomalies.