Geology of Niger

The geology of Niger comprises very ancient igneous and metamorphic crystalline basement rocks in the west, more than 2.2 billion years old formed in the late Archean and Proterozoic eons of the Precambrian.

The pre-Birimian crystalline basement rocks include gneiss and migmatite metamorphosed to amphibolite grade in the sequence of metamorphic facies.

The Liptako region, in the west has amphibolite, chlorite-schist, meta-andesite, meta-arkose, micaceous quartzites and garnet gneiss which are younger.

These rocks formed after a granite-gneiss complex in the area, but before the mudstones, tuff, quartzite, conglomerate and greywacke of the Amarasinde and Bellekoire beds.

More than half of the basement rock in the massif is metamorphic, including the Edoukel mesozonal micaschist, Azanguerene gneiss, Tafourfouzete letpynite[check spelling] and possible ophiolite of the Aouzeueur formation.

[2] During the Cambrian as multi-cellular life became commonplace, anorogenic magmatism formed ring complexes, that now comprise 30 different massifs in the Niger-Nigerian Younger Granite Province.

Niger also has vein-type copper deposits, with malachite and chalcopyrite associated with molybdenum, lithium and silver—or zinc and lead in the Proche-Tenere District.

The gold belt actually extends further east, past the Niger River, but is largely concealed by younger sediments and sedimentary rocks.

One hundred thirty five kilometers south of Niamey, is the Tapoa phosphate deposit Neoproterozoic and Cambrian sedimentary rocks of the Volta Group.

Ophiolites in the Abuzegueur overthurst[check spelling], in the Air region also show potential for platinum mineralization and may also have chromite, nickel and cobalt.

The Fantio deposit in the Liptako area has heavily weathered ultra-mafic rocks, with 0.8 percent nickel, totaling up to as much as 200,000 tons.