A geological mapping project report of Area H in Gayaza-isingiro district, southwestern Uganda
Abstract
The mapping exercise was carried out in gayaza, Isingiro district, Southwestern Uganda, with the aim of acquainting us with skills in geological mapping. 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 in which the study area was traversed and a mapping plan developed and various observations on outcrops were made and recorded. After field work, samples were sorted and taken to the laboratory for further analysis and data acquired on structures was interpreted and analyzed. The findings were compiled interpretations were made.
The structures that were found in the mapped area include; joints, beddings, laminations, faults, rods, boundinage, crenulations, quartz veins; these were mapped at different scales. The economic potential of the area is low since no economic minerals have been discovered. However, some of the economic activities carried out in the area include; farming, cattle keeping, quarrying, and brick making.
The lithology in Igayaza area comprises of shales, quartzites, conglomerates, phyllites, laterites, Aplites, and mylonites. The rocks were deposited in the order of shales followed by sandstones (later metamorphosed to quartzites) which were later intruded by granites and as a result of erosion and weathering the granites formed arena structures which predominates most of the Karagwe-Ankolean system. Sedimentation thought to have occurred in a shallow elongated basin on the lower Proterozoic crust. This was later followed by deformation of the meta-sediments by compressional forces which were accompanied by formation of folds. 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. The mapped area lies on a generally rugged topography with intervening valleys, flat topped ridges and rounded hills. The drainage pattern of the area is structurally controlled, like in faults zones, water flows through faults.
Geo-traverse was made after the mapping exercise in other areas like; Ibanda granite, Kitwe granite, Akabeba granite, Kitagata hot springs, Lake Mafuro (Crater Lake), and other areas and some information was noted on them in relation to the mapped area.