Origin and Emplacement Conditions of the Dibilo Lithiniferous Mineralization (Liptako, Western Niger)

The Dibilo Lithium pegmatites are located in the T?ra - Ayorou pluton, 4 km from the contact zone with the Diagorou - Darbani greenstone belt in the Niger Liptako province (Northeastern part of Man Shield, West African Craton). The main objective of this study is to specify the main geological characteristics of the lithium mineralization in the Dibilo pegmatites and to propose a metallogenic model of their emplacement. The methodology used consisted of fieldwork, laboratory work, and the use of discriminating reference diagrams. The Dibilo lithium pegmatites can be classified as Rare Element (RE), complex type, spodumene sub - type, and Lithium - Cesium - Tantalum family pegmatites. Four (4) types of pegmatites have been identified: (1) sterile pegmatites; (2) Li, Ta, W pegmatites; (3) Mo, Ta pegmatites; and (4) Mo, Ta, W, Be, Au pegmatites. Lithium mineralization occurs mainly as spodumene and secondarily as lepidolite and holmquistite. This lithium mineralization could result of a residual magmatic liquid from the fractional crystallization of the adjoining biotite - granite which corresponds to late magmatic liquids could result from the magmatic differentiation of the granodiorites. These granodiorites are thought to be the product of partial melting of metasomatized oceanic crust in the "lower amphibolite" facies, in an oceanic subduction context.