GEOLOGY AND ENVIRONMENTAL IMPACT ASSESSMENT AND BENEFIT OF GRANITIC ROCKS OF MINNA AREA, NORTHWESTERN NIGERIA

Abstract

Nigeria basement complex has shown that the older granites are high level intrusions emplaced by stoping and diapiric process and include spectrum of rocks varying in composition from tonalite through granodiorite to granite. The intense regional deformation which accompanied and preceded the emplacement of the older granite result in it pronounced and wide spread northeast trend. The granites termed older granites in Nigeria have been dated severally at 500-750 million years. Minna is situated in the central part of the Nigeria basement complex surrounded by rugged terrain of granitic rocks, this necessitates the geological and impact assessment of the granitic rock in Minna. Field study reveals eight granitic masses which occur as Paiko and Minna batholiths and as continuous ridge in north-south direction of about 18 kms and average height of 350 meters above sea level. In hand specimen, the granitic rocks vary from medium, porphyritic to coarse variety from light colored to medium dark colored.