Geology, Geochemistry and Petrogenetic Studies of the Precambrian Basement Rocks around Jimgbe, Northcentral Nigeria

Abstract

The field geological mapping of the area around South-Eastern part of Jimgbe, in Ajaokuta Local Government of Kogi State has been carried out, it lies 07o41' ?07o42'N and 06º44' ?06º45'E and has an extent of 3.42 Km2. Four (3) dominant rock units were revealed which are: Porphyritic granite, Migmatitic gneiss, Granite gneiss and Biotite gneiss. The minor rocks include quartzo-feldspartic intrusion and quartz vein. The area has different structures such as fold, fracture and foliation which trends NW-SE and NE-SW direction, this is allotted to the Pan-African Orogeny imprints. The petrographic analysis result shows that the four rock types are granitic in origin due to their high quartz and feldspar contents. The major mineral composition are quartz, plagioclase, microcline and biotite. Geochemical analysis result shows that SiO2 is the most abundant major oxide. The average oxide percentages are; SiO2 (69.25%), Al2 O3 (12.41%), CaO (5.72%), Na2 O (3.25%), K2 O (3.76%), MgO (2.76%), Fe2 O3 (1.79%), TiO2 (0.28%), MnO (0.33%) and P2 O5 (0.47%). These results shows that the rocks are calcic, and is also of high K-Calc alkaline in nature, the rocks majorly plot in the eugeosynclinal field except for sample T4 of the biotite gneiss which plot in the sedimentary field. They are mostly S-type peraluminous rocks except for the biotite gneiss (T11) which is an I-type peraluminous rock, these rocks are obtained from the upper mantle and lower crustal regions. They all plot in the magmatic field and also in the Granodioritic field.

Publication Info:

Author: Adamu, L.M.1 *, Umaru, A.O. 2 , Aliyu, A.E.3 , Ereosun, T.S.1 and Kitha, M.

Volume: 57

Issue: September

Published By: Journal of Mining and Geology, 2024-09-01