Petrogenetic links between rare metal-bearing pegmatites and TTG gneisses in the West African Craton: The Mangodara district of SW Burkina Faso

• Mangodara forms a dome cored by tonalitic gneiss, mantled granodioritic gneiss. Gneiss-granitoids derive from partial melting of Birimian greenstones. Residual melt syntectonic gneiss genesis formed rare-metal pegmatites. We describe the geological context rare metal-bearing pegmatites district (South-West Burkina Faso, Paleoproterozoic West African Craton) and discuss their petrogenesis links with host rocks. The exposes gneiss-granitoid complex structured in regional-scale dome, enclosing rafts amphibolite, micaschist paragneiss, to trondhjemitic gneisses. These gneisses enclose granitoid plutons, four populations pegmatites: titanite-allanite-, apatite-zircon-, garnet-columbite (Li, Nb) garnet-REE (Ti, Y, HREE)-bearing varieties. Rafts migmatitic paragneiss are chemically equivalent nearby greenstone belts. An origin is suggested diffuse contacts as well presence garnet-bearing or hornblende-bearing leucosome amphibolites, respectively. Textural continuity between granitic veins concordant foliation point segregation pegmatite-forming magmas. compositions plutonic rocks spread Na-rich pole K-rich pole. Granodioritic hornblende-biotite granodiorite potassic biotite granitoids define series attributed relatively low-pressure high-degree dominantly which accounts for low absent LILE HFSE fractionation compared paragneiss. Tonalitic-trondhjemitic trondhjemite peraluminous two-mica belong characterized K content strong depletion REE HFSE, might reflect plagioclase clustering after at high pressure HFSE-REE-bearing minerals. Thermodynamic mass balance modeling further corroborate these propositions implying that amphibolite about 5 10 kbars temperature 780 850 °C followed melt/solid fractional crystallization susceptible generate Na- series. U-Pb dating zircon titanite-allanite-bearing pegmatite 2094.3 ± 8.8 Ma apatite tonalitic-trondhjemitic apatite-zircon-bearing 2094 21 Ma, 2055 20 2041 33 respectively, confirm melting, crystallization-cooling occurred during Eburnean orogeny. Based on data, we propose (i) titanite-allanite- result residual (ii) garnet-columbite-bearing originate (iii) garnet-REE-bearing within