An integrated structural and geophysical approach to defining the structures of part of the Nangodi greenstone belt, northeastern Ghana

The application of integrated geophysical (aeromagnetic and airborne radiometric) and geological data has become more relevant in the investigation of subsurface geology with its inherent structures; this approach provides greater detail of structures and formations which are hidden beneath thick weathered zones. This approach was used to provide an in-depth study of the poly-deformational, structural and lithological character of parts of the Paleoproterozoic Nangodi Greenstone Belt in northeastern Ghana. The integrated method was specially chosen because of the paucity and lack of obvious lateral continuity of outcrops in much of the area. Processing and interpretation of aeromagnetic data led to the identification of structures and deformational features i.e. shear zones with related folds and faults. Combined with field evidence, three deformational events (D₁-D₃) were resolved within the study area. D₁ is marked by NW-SE crustal shortening which was responsible for the production of macroscopic folds that imparted the regional NE-SW foliation observed in the rocks. D₂, is a brittle-ductile deformational event mainly responsible for the production of a NE striking shear zone and some associated dextral strike slip faulting which were seen in the Gonzurudoug and Nangodi hills. D₂ deformation is seen as an angularly hinged fold, described as an intramylonitic fold. D₃ is responsible for the production of an ESE-WNW directed compressional force which produced folds with ENE striking axial planes as well as left lateral strike slip faults. Lithological boundaries were identified using ternary maps of radiometric data with confirmation from field observations.