Abstract
The Betare Oya and Woumbou-Colomine-Kette gold districts, located in the East Metallogenic Province of Cameroon, are characterized by a complex Neoproterozoic history of metamorphism, polyphase deformation, and widespread crustal anatexis and magmatism. Controversy exists on the timing of the metamorphic and magmatic events, particularly within the area of the Lom Belt, and accurate absolute ages and even geodynamic chronology pertaining to the tectono-magmatism are yet to be well constrained. New LA-ICP-MS U-Pb zircon ages, Lu-Hf isotope data, and whole-rock geochemistry of granitoids and metavolcanic-metasedimentary rocks from the Woumbou-Colomine-Kette and Betare Oya districts better constrain the tectonic evolution of eastern Cameroon. The U-Pb age data of 646.5 +/- 2.0 Ma, 643.7 +/- 1.8 Ma, 641.3 +/- 4.4 Ma, 641.4 +/- 3.5 Ma, and 620.9 +/- 2.6 Ma revealed that the granitoids from the Woumbou-Colomine-Kette district were emplaced during two main magmatic events at ca. 650-635 Ma and ca. 620 Ma. The zircon Hf(t) values between -13.80 and -6.20 with Hf-TDM model ages of 1.9-2.4 Ga, coupled with geochemical signatures show that granitoids were generated by partial melting of Paleoproterozoic supracrustal metasedimentary units and meta-igneous rocks during subduction and orogenic convergence. Metamorphic zircons from the actinolite-chlorite schist of the Lom Belt gave ages between ca. 655 and 585 Ma, implying that the metavolcanic-metasedimentary rocks of the belt were deposited prior to 655 Ma, then metamorphosed and deformed between ca. 655 and 585 Ma. Two age peaks of detrital zircons were measured at ca. 1035 Ma and ca. 784 Ma with the epsilon Hf-(t) values of -14.60 and -18.37 and +2.97 and +8.60, respectively. These data, coupled with those from previous studies, suggest that the Lom Belt may represent a suture zone between the Central and Southern Cameroon domains with an early rifting at ca. 784 Ma. In general, our U-Pb ages indicate compressional to transpressional deformational phases in the two districts at ca. 660-635 Ma (D1), 630-610 Ma (D2), and 600-580 Ma (D3). The latter D3 transpressional event was also associated with the formation of the widespread occurrences of orogenic gold, although the precise timing of gold deposition needs to be constrained.
NSTL
Elsevier