Field excursion report for Western Uganda

Abstract

This report covers the geological features that were encountered within the Karagwean –Ankolean sub-systems, which are part of the Kibaran system of East and central Africa. The specific study areas covered parts of South and south –western Uganda. It covers the different structures, history and processes of formation, measurements of structures and other micro-structures found within. Shale beds with a cyclic pattern were encountered around Kyabirukwa Hill which shows the different seasonal environments of deposition during formation. Shales are grey with dark and light layers. Extensively folded shales were encountered around Mabona hill but on a small scale. Micro –folds were seen on the shales in the same locality trending in the North-Eastern direction. Jointing evidenced by quartzite veins running across the formation is an indication of lines of weakness formed as a result of erosion and weathering of shale materials. Kaolinite minerals were deposited within the joints. Tin deposits were encountered around Nyarubungu hill, around Kikagati near the Uganda-Tanzanian Border. The tin host rock was a grey quartzite pegmatite of varying thickness which evidenced crystallization of mineralizing solutions through zones of weakness where mining takes place. Granites of coarse grained pegmatite rock were encountered around Ibanda where the rocks were rich in Potassium-Feldspar, black biotite quartz and albite(Plagioclase). Xenolith rock formations were randomly scattered within the granite. Other granites were also found around Ntungamo, Chitwe and Akabeeba rock formations.