| dc.description.abstract | The geologic mapping exercise was carried out in Igayaza, Isingiro district found in south western part of Uganda. The mapped area is within the rocks of the Karagwe Ankolean system which stratigraphically over lie the rocks of the Basement complex. The Karagwe-Ankolean (K-A) system (1400-950Ma) in Uganda forms the northern most extension of the Kibaran mobile belt.
The project was carried out with the aim of equipping the students with the various skills in geologic mapping, data collection methods, processing and dissemination. The whole exercise involved collection of field data, processing of the collected data in the laboratory and reporting about the stratigraphy, structures, petrography and metamorphism and regional synthesis.
The area is generally characterized by a hilly topography with superseding narrow and broad low lying areas which could have evolved due to differential weathering. The area is also characterized by dendritic drainage pattern. Settlement in the area is nonlinear and the relief is generally high making it normally difficult to access. Land use is mainly agriculture and quarrying of stones for construction purposes.
The main rock types in Gayaza include shales (ferrogenous and grey), quartzites, breccia (found in area A and C), conglomerates, phyllites, laterites. The rocks were deposited in the order of shales followed by sandstones which were later metamorphosed to quartzites that were later intruded by granites. Due to erosion and weathering the granites formed arena structures which dominate much of the Karagwe-Ankolean system.
The major geologic structures encountered in the area are bedding, joints/fractures faults and folds all exhibiting two major trends which include 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.
Petrographic studies confirmed presence of quartz and clay minerals (as the dominant minerals) together with some micas, alkali feldspars and iron oxides in the rocks of the mapped area. 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. Sandstones and shales were metamorphosed to quartzites and phyllites respectively. Deep, quiet and shallow water dynamic environments of deposition were proposed due to the presence of shale and quartzites and some structures such as beds and laminations in shales.
No economic minerals were found in the area however, some industrial minerals of high place value such as sand, kaolin, shales and quartz were present and are mainly used for construction works. The major economic activities carried out include; crop growing (especially matooke), animal keeping (on a small scale), charcoal burning and quarrying. | en_US |
