b'The origin of the Bangui magnetic anomalyFeatureGOCO6s and XGM2019) and a magnetic database (EMAG2-v3).(3)establishing correlations with the underlying geological Each of these datasets was subjected to separate processing. formations. Subsequently, upward continuation and spectral The first processing stream consisted of terrain correctionsanalysis methods were used to determine the depths to the applied to the ground gravity data (Figure 4a). Thesebottom of the magnetic sources. The location of potential corrections were applied with an average density ofsources was also determined by deconvolution along some 2670 kg/m3 , considering a digital elevation modelselected magnetic profiles. Once the geometric parameters extended over an area between 0-22N of latitude andwere determined, they were used to build 2.5D and 2.3/4D 5-50E of longitude. All the data were interpolated with acrustal models highlighting the magnetic intrusions beneath 10 km step to obtain the Complete Bouguer. The Completethe BMA.Bouguer obtained was used as the base for the firstResults and discussionestimation of the Moho depths in Central Africa (Cameroon and Central Africa) using the spectral analysis methodThe first result of this work was a complete Bouguer anomaly (Spector and Grant 1970; Bhattacharyya and Leu 1975;map for the Central African sub-region (Cameroon, Central Tselentis etal. 1988; Poudjom Djomani 1993; Nwobgo etal.African Republic, Figure 4a), which is an essential support for 1998; Nnange etal. 2000). any other gravity analysis. This result allowed the observation Given the (1) sparse distribution of ground gravity dataof a coalescence of short and long wavelength anomalies, with (Figure3) in some local areas, which is a consequence ofamplitudes ranging from -100 to 20 mGals. These anomalies the field conditions, (2) coalescence between wavelengths,have allowed the characterisation of two major tectonic informing on different crustal interfaces, satellite-only gravitystructures: the northern edge of the Congo Craton and the data (GOCO6s and XGM2019) derived from the CHAMP, GOCE,Central African Orogenic Belt (CAOB). A comparison of the GRACE and SLR missions have been used. A non-linear gravityresults obtained from the Complete Bouguer map was made inversion approach developed by Uieda and Barbosa (2017)with reference to Poudjom etal. (1995); Poudjom etal. (1992); was applied to these data. This approach allowed imagingBoukeke, (1994). The similarity between the extension of the and discussion of the crustal architecture in the North-Centraldominant tectonic structures (Cameroon Volcanic Line, Central African region based on successive filters; also analysis ofCameroon Shear Zone, Adamawa Plateau, Northern edge of the different geodynamic contexts of the BMA sources.the Congo Craton and the Southern Chad Basin) allowed the The mechanical behaviour of the lithosphere can be easilyvalidation of the various preliminary results.analysed by estimating the coherence parameters between theThe evolution of the crustal architecture in the North-Central topography and the Bouguer anomaly. African region, the estimation of Moho depths (Figure 5a) and elastic thicknesses (Figure 5b), and the understanding of the Magnetic data were extracted from the EMAG2-v3 globalmechanical behaviour of the lithosphere were among the database resulting from the CHAMP satellite mission. Differentother advances made in this thesis. The crustal architecture digital signal processing methods were applied, dependingwas determined by means of two different databases, and on the amplitude and geometry of the observed anomalies.used different approaches (spectral analysis and a regularised The first treatments consisted of a stable reduction to thenon-linear inversion methods) to assess the regions crossed pole of the magnetic anomalies (Figure 4b), pseudogravityby the BMA. The results showed that the magnetic structures and analytical signal. All of them allowed (1) location ofassociated with this anomaly are strongly linked with the the magnetic anomalies directly above their sources; (2)cratonic structures. Furthermore, the estimated crustal analysis of the geometry and the amplitude of the anomalies;thicknesses between 15 and 45 km were compared to the Figure 4.(a) The Complete Bouguer anomaly; (b) the total magnetic intensity map reduced to the pole (Njiteu etal. 2021a)47 PREVIEW FEBRUARY 2022'