The material used consists of 1) Landsat-8 ETM⁺ (Enhanced Thematic Mapper) satellite images with a resolution of ~30 m (bands 1 to 5) and 15 m (panchromatic band 8); 2) DEM (Digital Elevation Model) with resolution of ~90 m; 3) airborne geophysical images. The Landsat-8 ETM⁺ image was acquired at March 14, 2020 during the dry season. In the Mako area (Sénégal), during this period, the disruptive effect of cloudiness and vegetation is minimized except for some isolated fumes due to bush fires. The characteristics of the satellite images used are mentioned in Table 1.

For the geophysical images, the data (airborne images) were collected in 2009 by the company Fugro (Fugro Airborne Surveys Corp) for the benefit of the Mines and Geology Department (DMG) of Ministry of Industry and Mines of Senegal. They were carried out within the project of “PASMI” (Support Program for the Mining Sector), which aims to consolidate Senegal’s geoscience infrastructure. We obtained these geophysical data through collaboration between the “DMG” and the Geology Department of the University Cheikh Anta Diop of Dakar.

The airborne geophysical campaign acquired high resolution data, which characteristics are in Table 2.

The airborne geophysical images used in this work result from the processing of geophysical data from the DMG. The software used for image processing are Geosoft Oasis Montag and Envi 4.2 for geophysical and satellite data respectively. The combination and analysis of multi-source data are carried out using ArcGis software.

The validation of the preliminary tele-analytic map is carried out by combination and comparison through a GIS, of structural data from images processing and those identified and located in the field. The final map will take into account the geological data of the pre-existing maps (lithology and tectonic structures). The progress of our approach is presented in Figure 5.

The lineaments extracted on the filtered image (panchromatic band 8 of Landsat-8 ETM⁺ and DEM image) in the different filtering directions (NS, EW, NW-SE and NE-SW) are systematically compared to the lineaments obtained on the multispectral images (4.3.2 bands combination of Landsat-8, ETM⁺) and on geophysical images before being confirmed and digitized. Thus, we will avoid repeating or adding elements that are not likely to be geological lineaments

(road, wooded boundaries and power lines, etc.). To avoid the segments repetition on this synthesis map, a selective elimination of all the overlapping lineaments is carried out. The tele-analytic map of lineaments from the images processed (Figure 6) is superimposed on the geological map of field data (Figure 7) in order to check the existing correlations and improve the geological map of the area. The stereographic projections of the directional measurements resulting from these different images lineaments are attached as insets to the aforementioned figures. They are compared to that of the field data.

For satellite images, it appears that the linear structures resulting from the enhanced and filtered DEM image are mainly oriented NNE-SSW and NS, with some NW-SE directions and rare EW directions (Figure 3(b)). On the enhanced and filtered panchromatic band (8) images of the Landsat-8, ETM⁺, the NNE-SSW oriented lineaments remain in the majority (Figure 3(a)). However, NW-SE trending lineaments are more frequent than those NS trending, unlike the results obtained from DEM images. In addition, this Figure 3(a) shows locally folded structures which are arranged in echelon along a potential dextral

shear corridor.

Supervised lineament analysis on multi-spectral 3.4.2 enhanced and color-combined bands of Landsat-8 (ETM⁺), corroborates the predominance of the NNE-SSW and NS oriented lineaments (Figure 4). The NW-SE trending

lineaments, although relatively infrequent, are well distributed throughout the study area and sometimes form large structures which often cross-cut previous lineaments directions. E-W oriented lineaments are rare. We can also note that the trajectory of the large tectonic structures clearly appears on these satellite images. In this case, we can notice that the N-S and NNE-SSE oriented lineaments are sometimes linked to the same linear structure whose trajectory has undergone a great amplitude torsion during the deformation (Figure 4(a)).

For the aeromagnetic geophysical image, the result of the data processing highlights the sub-surface geological structures which appear as multidirectional lineaments associated with elliptical magmatic bodies. The vertical derivate of RTP map, clearly shows the response of the dykes as short wavelength linear anomalies that cross the study area in three main directions: NNE-SSW to NE-SW, N-S, NW-SE and E-W (Figure 4(b)). The comparison with the bibliographic data indicates that dykes are mafic rocks (dolerites) which present a post-Birimian age and which are most often intrusive in the Eburnean faults ( [1] [11] ).

These lineaments are mainly NE-SW oriented, followed by the N-S then NW-SE oriented lineaments. The E-W oriented lineaments are quite rare (Figure 4(b)). In addition, these images show folded or crenulated lineaments, locally arranged in echelons following a sinister potential shear corridor. Indeed, the E-W oriented lineaments are often crenulated by those NE-SW and NW-SE oriented. They would likely be the early structures in the study area. Locally, they are trapped and micro-folded within the NE-SW oriented tectonic corridors (Figure 4(b)).

The field data collected in the area are presented in Figure 7. We are represented the mainly structures such as shear zones, fold axis, schistosities, lineations, faults and major fractures.

The schistosities directions recorded in the field are represented on the field data map and projected as roses directional (Figure 7). The N75˚ to N100˚ oriented S₁ schistosity, is the less preserved in the study area. It presents a variable dip direction. It is marked by foliation planes which often intersected or crenulated by posterior schistosities (S₂ and S₃). The S₂ schistosity is N00˚ to N35˚ (S_2a) and N150˚ to N160˚ (S_2b) oriented. It constitutes the best preserved structures in the study area. They locally intersect the S₁ schistosity (Figure 8(a)). In addition, these S_2a and S_2b schistosities are mainly located within major co-directional shear zones and often exhibiting sinister movement ( [34] ). These are mainly the Lamé (LSZ) and Mako (MSZ) shear zones (Figure 7). The NNE-SSW and NW-SE (N20˚ and N130˚) oriented S₃ schistosity, is weakly recorded in the area. It is often located in minor shear zones which show dextral movement (Figure 8(b)). Folds of variable geometry and size are also identified in the area (Figure 9). These different tectonic structures are associated with three phases of Eburnean deformations D₁, D₂ and D₃ ( [23] ). The Eburnean D₁ deformation phase, responsible for the S₁ schistosity, is a tangential tectonic which causes thrust towards the W and the ENE direction ( [34] ).

The Eburnean D₂ deformation phase is a generally sinistral transpression tectonics which causes anastomosed shear zones along the S₂ schistosity directions (N00˚ to N35˚ S_2a, and N150˚ to N160˚ S_2b). The Eburnean D₃ deformation phase is a dextral transtension which reactivates the structures of the D₂ deformation. This D₃ Eburnean deformation phase is of low intensity taking into account the others tectonic structures generated in the study area.

The lineaments resulting from satellite images (DEM, landsat-8 ETM⁺) and aeromagnetic geophysics as well as field data (schistosities, faults and shear zones), present similar orientations (Figure 3, Figure 4 and Figure 6).

On these different images, NE-SW oriented lineaments are more frequent followed by those NS oriented, then NW-SE oriented lineaments. E-W oriented lineaments are quite rare and appear particularly on the aeromagnetic image. In the landsat-8 ETM⁺ (colored composition) and aeromagnetic geophysical images, curvilinear, folded and crenulated lineaments appear (Figure 3(b), Figure 4(a)). The distribution and the relative importance of the different direction families of lineament can be interpreted in comparison with the results of field data and previous work ( [2] [3] [23] [34] ).

The N75˚ to N100˚ oriented S₁ schistosity, is poorly preserved in the field and often intersected or crenulated by late schistosities (S₂ and S₃). It would correspond to the E-W oriented lineaments which are also infrequent on the studied images (Figure 3 and Figure 4). In addition, these E-W oriented lineaments show on Landsat-8 ETM⁺ (colored composition) and aeromagnetic geophysical images the wrench and wrinkle deformations relative to the NE-SW and NW-SE oriented lineaments which are associated with the late deformations (D₂ and D₃).

The NS to NE-SW and NW-SE oriented lineaments are coincide with the direction of the S₂ schistosities, in particular S_2a (NS to NE-SW oriented) and S_2b (NW-SE oriented) and the large meridian to sub-meridian thrust or reverse-shear zones which are identified in the study sector (Figure 7). These Eburnean D₂ structures of the deformation intersect and create the crenulation of the S₁ schistosity (N75˚ to N100˚ oriented) and associated thrust zones ( [34] ).

The NNE-SSW and NW-SE oriented S₃ schistosity which is weakly recorded in the field, is not clearly identified on the images and remains confused with the structures of the D₂ deformation. (Figure 8(b)). However, it would be correlated with a part of the NNE-SSW and NW-SE oriented lineaments.

These lineaments from different images would be relative to geological structures associated with Eburnean and post-Eburnean tectonic events in the Mako area. Their structural and geometric relationship support a polyphase Eburnean deformation. Most of the NS and NNE-SSW oriented lineaments, and part of the NW-SE oriented lineaments would be related to the D₂ major Eburnean deformation phase. These lineaments are correlated with the S₂ schistosity of the D₂ Eburnean deformation phase and essentially correspond to shear zones, faults and fold axis. Most of these D₂ tectonic structures show sinistral movement. Thus, the trajectory of Mako Shear Zone (MSZ) which represents one of the major tectonic structures of the area has been clearly specified. The E-W oriented lineaments predate the D₂ Eburnean deformation phase, because they are cross-cut, crenulated or sheared by these former. Indeed, these E-W lineaments would be relative to the Eburnean D₁ deformation phase characterized by thrusting towards the W and the ENE ( [34] ). Some NNE-SSW and NW-SE oriented lineaments intersect or shift the D₂ Eburnean deformation structures and would therefore be posterior. These structures would be relative to a late D₃ Eburnean phase or even post Eburnean deformation ( [23] ).