Interpretation had confirmed the
dominance of the basement complex underlying the entire area of Northern -Nigeria and
some part of South-Eastern and some part of South West Nigeria.
The basement
complexes were mainly composed of igneous and metamorphic rock of complex
structure including the older rock of
Precambrian age and the late protozoic
meta-sediments most of which are high metamorphic graded like Para genesis,
basic and calerous schist, marble and quartzite orthogenesis and the early Eburnean
granite.
In the North West, the rock types and sequence of event recognized can
be correlated with the Bueen and Togo formation in Ghana, Togo and Dahemcy and
Phanisian chain in the Ahagar, having been acted upon by two tectonic
metamorphic cycles and series of consequent metamorphism migmatization and
grnitization, the original rock and materials of the basement rock material of
the basement have been deeply modified yielding the complex nature, relict
rofit and xenoliths in migmatite and granite.
But these relict are believed to
be of an older supra crustal cover probably Birrimian age and are termed older
meta-sediments. For clear differentiation from the later protozoic supra
crustal sediments referred to as younger meta-sediment which form well define
approximately N-S trend belt extensively developed in the North –West and are
believed to represent the remnant of an extensive supracrustal cover.
The
explanation on the evolution of the Nigeria basement and the variable
nature of the pan-African event (McCury 171 and Grant 1970) proves a
considerable variation on the younger meta-sediment. These range from pramitic
to pelitic sediments of low facies and interbedded lavas. These have been
sleeply folded along with the basement complex during the pan-African orogeny
so that they now occur in synclinorial trough resembling gemstone. Migmatite
association of cratonic region (Wright and McCury, 1970).
During
the pan-African orogenic cycle event, intrusions of older granitic series have
been recorded. And with more complicated folding of the older meta-sediments in
contrast to the structure of the younger bed, yielding a complex deformational
history.