Geological mapping project report of Gayaza Isingiro District, Uganda

Abstract

Geological mapping activities were carried out in Gayaza Isingiro district in western Uganda in Gayaza synclinorium which is within the Karagwe-Akolean system of rocks. The mapping program is principally geared toward the orientation of students to the skill of geological mapping such as; collecting field data, using field equipments representing field data on base maps and interpreting it. The report is composed of detailed geological study of area E in terms of rock types, metamorphism, stratigraphy, structures and economic activates as well as the regional synthesis which cover Gayaza synclinorium and surrounding areas within the Karagwe-Ankolen system. The rock types in area E includes; shales, quartzites, and few conglomerates, in addition to the rock types mapped in area E, the rest of Gayaza synclinorium include; slates mudstones, phyllites, and granites in the arena. The type of metamorphism that affected Gayaza area is mainly regional and of low grade evidenced by foliation and some index minerals such as chloride. The grade of metamorphism increases towards the arena due to contact metamorphism resulting from granitic intrusion. Sandstone and shale were metamorphosed to quartzites and phyllite respectively. Deep quiet and shallow water dynamic environment of deposition were proposed due to the presence of shale and quartzite and some structures such as beds and lamination in shales. The major structures in the area mapped include; beddings, faults, folds and joints all exhibiting two major trends; the northwest-southeast (NW-SE) trend which is similar to that of the regional folds and the northeast-southwest (NE-SW) direction similar to that of the cross folds. The minor structures include; micro-folds, micro-faults, quartz veins, boudins, rods, foliation, lamination and mud cracks. No economic minerals were found but some industrial minerals of high place value such as sand, kaolin, shales and quartzite, mainly used for construction works do exist. The major economic activities in Gayaza area include: crop growing (especially matooke), animal keeping (on a small scale) and brick layering