The rocks of the basement complex of Nigeria have
been described profoundly in different publication of geological survey of
Nigeria (GSN) and work by Oyawoye (1972) Ajibade (1976) McCury (1976).
Rahaman
(1976) suggested that the first expositional phase of sedimentary which took
place about 2500ma ago and referred to this group as the older meta-sediments.
The
phase was accompanied by another suit of sediments laid down some 1000 – 8000ma
ago and referred to this as the youngest meta-sediments.
Based
on the geophysical (radiometric) data from rock in the Nigeria
basement complex indicate at least two orogenic period ie, Eburnean orogeny
(1950 ± 250ma) and pan-African, orogeny (600 ± 150ma) resulted in the replacement of
the older granite, which account for the wide spread of amphibole facies
metamorphosis of basement complex.
Grant
(1973 – 1978), McCury 1773 – 1776, Rahaman 1976, Fiteches et al 1985, they were
of the view phase of fold were associated with the initial of the fold is
greatly Isoclinals fold with E-W trending axial planes and later folding phase
which yield the dominants and NW – SW trending structure.
2.2
REGIONAL STRATIGRAPHIC
SEQUENCE
Table 1: Regional stratigraphy sequence
Age
|
Sucession
|
Rock type
|
Jurassic
|
Maradum group
Kisemi group
Burashika
|
Granite,
granodiorite, synenite migmatite
|
Cambrian upper
proterozoic
|
Older granite
|
Granite,
granodiorite, syenite migmatite
|
Upper proterozoic
|
Younger
meta-sediment
|
Phyllite, schist
|
Precambrian
|
Older
meta-sediment and gneiss
|
Quartzites,
marble, basic, rock and calcareous schist, biotite and hornblend gneiss,
granite.
|
Table 2: Summarized succession table showing the
outcrop study and their various rock types
S/N
|
OUTCROP
|
ROCK TYPE
|
1
|
Albrocky
filling station Nassarawa Eggon
|
Banded
gneiss
|
2
|
Nassarawa
Eggon
|
Rhyolite
|
3
|
Mada hill
|
Younger
granite
|
4
|
Agbonju hill
|
Migmatites
|
5
|
Wowyen
|
Banded
gneiss
|
6
|
Mada River valley
|
Migmatites/Amatexite
|
7
|
11km for
Akwanga
|
Banded
gneiss
|
8
|
Mandara
|
Mignatite and mets dolerite sill
|
9
|
Ando River valley
|
Schist
|
10
|
Shamage
village
|
Older
granite
|
11
|
Mante
|
Older
granite
|