Saha Fouotsa Alliance Nicaise^1,, Tchameni Rigobert¹, Nomo Negue Emmanuel², Daouda Dawaï³, Penaye Joseph⁴, Fosso Tchunte Periclex Martial¹

Field petrographic and structural data of the Mbé-Sassa-Bersi area exposed two main group of rock (metamorphics and plutonics) which were affected by polyphase deformation. The structural evolution is marked by four deformation phases called D₁, D₂, D₃ and D₄. The geometrical arrangement of D₁ structures (flat-lying foliation, horizontal lineation, recumbent folds and overlapping) allow to linked this deformation phase to tectonic nappe verging toward SSE. The second deformation stage (D₂) corresponds to simple shear dominated transpression and characterized by the evolution of the Tcholliré-Banyo shear zone (TBSZ) that showing sinistral movement. The third deformation phase (D₃), is marked by strain partitioning induced by transpression and links to the evolution of the Central Cameroon shear zone (CCSZ) that displays dextral motion. D₁, D₂ and D₃ are associated to migmatization, development and emplacement of granitic magmatism. During D₂ and D₃, the magmatic rocks are emplaced under the control of the two main crustal shear zones (TBSZ and CCSZ). D₄ deformation is responsible for the development of faults, fracture and joints and corresponds to brittle tectonic. The main NW-SE direction of faults and fractures suggest that D₄ stage shows traces of the Benue trough. On the whole, Nappe tectonic, followed by transpressive tectonic are the main tectonic type developed during the Pan-African Orogeny in Central North Cameroon.

Central African orogenic belt, central Cameroun domain, shear zone, nappe tectonic, transpression, strain portioning