PREVIOUS WORK ON ROCKS IN NASSARAWA STATE

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