Single-zircon U-Pb geochronology and petrogenesis of Pan-African granitoids associated with gold-bearing quartz veins in the Ngoura-Colomines area, Eastern Cameroon

LA-ICP-MS zircon UPb geochronology was combined with field study, petrography, and whole rock geochemical data to constrain the age of the Ngoura-Colomines granitoid plutons in the central domain of the Pan-African North Equatorial Fold Belt (PANEFB) in Cameroon and to define the relationship between the plutons and gold mineralization in the area. In the field, small plutons of biotite granite, megacrystic leucogranite, and granodiorite are generally surrounded by a larger body of alkali feldspar granite, which in turn intrudes gneisses. Two granite samples yield crystallization ages of 629.8 ± 1.4 Ma and 630.9 ± 2.5 Ma, and a granodiorite sample was dated to 633.0 ± 2.4 Ma. All the granitoids exhibit a distinct I-type continental margin arc affinity, indicating their formation in a subduction zone environment, but deformation fabrics extending to intense mylonitization imply a syn-tectonic setting, which we associate with the onset of the Pan-African collisional orogeny in this area at or before 630 Ma. The gold-bearing quartz veins cross-cut the dated plutonic rocks, suggesting that the gold mineralization event is younger than 630 Ma. Concordant inherited zircon grains indicate a series of earlier magmatic events between 955 and 668 Ma, whereas a number of discordant inherited zircons reveal the influence of Paleoproterozoic (1960 ± 83 Ma) and Mesoarchean (3072 ± 13 Ma) reworked materials, likely from the Congo Craton, in producing the investigated Neoproterozoic granitoids.