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

摘要

This study was carried out in the Lom series in Cameroon, at the border withCentral African Republic, located between the latitudes 5~(°)30~(′)–6~(°)?Nand the longitudes 13~(°)30~(′)–14~(°)45~(′)?E. A multi-scale analysis ofaeromagnetic data combining tilt derivative, Euler deconvolution, upwardcontinuation, and 2.75D modelling was used. The following conclusions weredrawn. (1)?Several major families of faults were mapped. Their orientationsare ENE–WSW, E–W, NW–SE, and N–S with a NE–SW prevalence. The latter arepredominantly sub-vertical with NW and SW dips and appear to be prospectivefor future mining investigations. (2)?The evidence of compression, folding,and shearing axis was concluded from superposition of null contours of thetilt derivative and Euler deconvolution. The principal evidence of the local tectonics was due to several deformation episodes (D1, D2, and D4) associatedwith NE–SW, E–W, and NW–SE events, respectively. (3)?Depths of interpretedfaults range from 1000 to 3400?m. (4)?Several linear structures correlatingwith known mylonitic veins were identified. These are associated with theLom faults and represent the contacts between the Lom series and thegranito-gneissic rocks; we concluded the intense folding was caused by senestraland dextral NE–SW and NW–SE stumps. (5)?We propose a structural model of thetop of the crust (schists, gneisses, granites) that delineates principalintrusions (porphyroid granite, garnet gneiss, syenites, micaschists,graphite, and garnet gneiss) responsible for the observed anomalies. The2.75D modelling revealed many faults with a depth greater than 1200?m andconfirmed the observations from reduced-to-Equator total magnetic intensity (RTE-TMI), tilt derivative, and Eulerdeconvolution. (6)?We developed a lithologic profile of the Bétaré-Oya basin.