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

Abstract

This study was carried out in the Lom series in Cameroon, at the border with Central African Repub lic, located between the latitudes 5°300-6° N and the longi tudes 13°300-14°450 E. A multi-scale analysis of aeromag netic data combining tilt derivative, Euler deconvolution, up ward continuation, and 2.75D modelling was used. The fol lowing 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 lat ter 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 asso ciated 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 delin eates principal intrusions (porphyroid granite, garnet gneiss, syenites, micaschists, graphite, and garnet gneiss) respon sible for the observed anomalies. The 2.75D modelling re vealed many faults with a depth greater than 1200 m and con firmed the observations from reduced-To-Equator total mag netic intensity (RTE-TMI), tilt derivative, and Euler decon volution. (6) We developed a lithologic profile of the Bétaré Oya basin.