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.