Tectonics and LA-ICP-MS U–Pb zircon geochronology of the Boula Ibi Region (Northern Cameroon Pan-African Orogenic Belt)

The Boula Ibi Region basement in northern Cameroon consists of paragneisses alternating with amphibolites. They are intruded by pre- to post-tectonic granitoids differentiated into meta-diorites concordant with metasediments, meta-monzonites, monzodiorites, syenites, granites as well as felsic to mafic dykes, calcite and quartz-feldspar veins. The region is affected by a polyphase ductile D1–D2 deformation consisting of: D1 lateral flow regime that totally transposed the S0 bedding into the S0/1 foliation in paragneiss and amphibolites; D2 pure shear dominant transpression phase overprinting S0/1 into a subvertical S0/1/2 in meta-sediments and causing a S2 steep foliation in meta-diorites and meta-monzonites, a L2 lineation, B2 boudins F2 folds, and C/S structures. The sinistral and dextral nature of dykes, veins and fractures indicate a variety of the brittle tectonic phase. LA-ICP-MS U–Pb zircon data show that Pan-African deformation duration is >680 Ma and >580 Ma. This duration of the Pan-African orogeny in Northern Cameroon Domain is ~145 Ma which is similar to 150 Ma obtained in the Yaounde Group (Southern Cameroon Domain).