Geology of the Pan-African basement Complex in Ube-Wulko area of Akwanga, North Central Nigeria

The Ube-Wulko area of southeast Akwanga falls within the Pan-African remobilized Basement Complex of northcentral Nigeria. It consists of intensely multi-deformed high grade polymetamorphic basement rocks, predominantly composed of migmatitic gneisses and schists and subordinate quartzites, marbles, and pegmatite and dolerite dykes which intrude mainly the migmatitic gneisses. The structural grains of the metamorphic rocks trend N-S to NE-SW, while about thirty weakly foliated and non-foliated pegmatites and several dolerite dykes are structurally controlled along ancient NW-SE and NE-SW tectonic lineaments. The foliated pegmatites intrude only the migmatitic gneisses, while the non-foliated pegmatites intrude both the migmatitic gneisses and schists. Schists represent the oldest rock unit and dolerites, the youngest. Lithologic characteristics of the metamorphic sequences suggest sedimentary parentage. Mineral composition (kyanite, sillimanite and calcic plagioclase), migmatization and complex deformation indicate at least medium pressure-high temperature amphibolite facies of the Barrovian type. KEY WORDS: Petrology, structure, metasediments, Basement, Akwanga