Structural and kinematic analysis of the Nkondjock shear zone, central Cameroon: implications on the geodynamic evolution of the Central African Fold Belt

Detailed petrographic and structural investigations were undertaken in the Nkondjock area to document the tectonic evolution of this portion of the Central African Fold Belt (CAFB) and unravel the geodynamic model of the whole CAFB. The Nkondjock area, which corresponds to the SW extension of the TBSZ trending NNE-SSW and the CCSZ, is made up of a syn-tectonic plutonic complex (two mica granites and granodiorites) that intruded migmatites, gneisses, and amphibolites. Structural analysis reveals four main stages of deformation (D 1 –D 4 ): The D 1 phase is a relict phase characterized by the S 1 foliation with the general orientation of N-S to NNE-SSW and a shallow to medium dip toward the NW or SE; sinistral and dextral shear zones developed during the D 2 and D 3 deformation phase, respectively. The D 4 phase is represented by the fractures and NE-SW to NW–SE kilometer-scale faults. The microstructural analysis reveals a continuous deformation from the magmatic to the solid state. The geodynamic evolution of the CAFB in the Nkondjock area comprises (i) a relict N-S to NNE-SSW D 1 phase probably established during the convergence of the Saharan metacraton and the northern edge of Congo Craton, (ii) sinistral syn-D 2 shear initiated by N-S trending stress and probably evolved and reoriented toward NNE-SSW to NE-SW between ca. 624–600 Ma, and (iii) D 3 dextral tectonics overprinting the D 2 sinistral structures between ca. 564 and 558 Ma (Ngako et al., Gondwana Res 14:509–522, 2008 ; Kamguia Kamani et al., Precambrian Res 353:106015, 2021 ). The correlation of the studied shear zone with well-documented Patos and Pernambuco faults (NE Brazil) suggests that the Nkondjock shear zone (NSZ) forms part of the Pan-African shear zone system extending from central Africa to NE Brazil.