Geological Mapping Project of Area-G in Igayaza, Isingiro District, Western Uganda.

Abstract

The Geological mapping exercise was carried out in Area G found in Igayaza, Isingiro district, western Uganda for 7 days, with the objective of enabling students to acquire skills in geological field mapping and data collection techniques which can be applied in future prospective petroleum exploration. The mapped area is within the Karagwe-Ankolean system of rocks (ca. 1400-950 Ma), which is the northern most extension of the Kibaran mobile belt. The mapping exercise involved conduction of field work based on surface geological mapping. Various techniques of geologic mapping such as pacing, traversing, rock sampling and making observations were employed. The samples collected from the field were analysed on a macroscopic and microscopic scale to obtain more information about the rocks encountered in the field. Area G lies on a rugged topography with intervening valleys and rounded hills. The lithology in area G is majorly composed of shale formations that are found on the slopes of hills and in valleys between ridges, and quartzites that are mainly found at the ridge summits occasionally with semi-persistent conglomerates. Shales are majorly composed of feldspars, kaolinite, quartz, chlorite, iron oxides and calcite. The rocks were deposited in deep, quiet and shallow waters in the order of shales followed by sandstones that later metamorphosed to quartzites that occupy the top of hills. The type of metamorphism that affected these rocks is mainly regional and of low grade evidenced by foliation and some index minerals such as chlorite. The major structures in the area are beddings, foliations, folds, joints, faults, fractures and quartz veins. The beddings in shales majorly strike in the North East direction and dip in the South west. Folding is mainly of two major types i.e., regional folds whose fold axes trend in the NW-SE direction and the cross folds whose fold axes trend in the NE- SW direction. Area G has low economic potential since no economic minerals were observed in the area. The economic activities being carried out include farming, cattle grazing, quarrying and brick making.