Figure 28. Representation of all quartz veins in tonalite envelope with grades

7. LITHOSTRATIGRAPHY OF THE STUDY AREA

In order to better understand the settng of gold mineralization, meticulous work has enabled the mapping of the Ouarigué prospect to be carried out.
The geology of this prospect is composed from west to east of argillite, tonalite, and sandstone. This tonalite is a small intrusion in the center, and we have the diorite dykes to the east. Then, a more precise block diagram was produced from the trench data and the drilling holes. Structural measurements were taken in order to characterize the mineralized structures. It follows a correlation of the structures coming from the trenches with those of the core drillings hole. This work made it possible to produce this block diagram which presents the different lithologies, the deformations D1, D2 and D3 ( Figure 27) .
The lithostratigraphy of the study area is as follows: The setting of the metasedimentary basin on the basement is followed by bedding. Then, the D1 deformation appears and followed by regional metamorphism. Due to the position of the Ferkéssedougou batholith three kilometers west of the prospect, the D1 deformation is insignificant in the study area. Then, there is a tonalite intrusion which introduces the D2 deformation followed by the hydrothermal supply which leads mineralization. Finally, several diorite dykes (D3) intersects this lithological setting and causes another gold mineralization.