| dc.description.abstract | The geological mapping project was carried by the year 2 students from the department of Geology and Petroleum, Makerere University. The field mapping duration was seven days (that is to say; from 31st Jan,2022 to 7th Feb 2023).The major aim of this field mapping was to train students to obtain hands-on experience in field geological mapping activities from field preparations to geological written report and practically learn field geological mapping and field data collection techniques and procedure. The study area is Gayaza in Isingiro district in Western Uganda. This area is part of the karagwe-Ankolean system of rocks which is the name given to the rocks of the Kibaran belt in Uganda. The area is divided into different segments with each segment assigned to a group of students. The mapped area ( segment) which is fully discussed in this report is area I. The area was traversed while making observations of rock units, mineralogy and structures at the same time taking measurements on attitudes of the different geological structures. Samples were also taken and thin sections created. The methods used after field trip include laboratory petrographic analysis and interpretation using a microscope, structural data analysis and interpretation using stereonet software and use of ARCGIS to digitize and draw cross sections from the map.
This looks at the study of the general geology, stratigraphy, structure, petrography and metamorphism of the K-A system in southwestern Uganda as the northern extension of the kibaran mobile belt.
Isingiro area is relatively low to medium in elevation. Most of the areas in Isingiro district Uganda covered by the conspicuous Karagwe-Ankolean system which is part of the Kibaran belt of Central Africa system of rocks on which the geologic mapping exercise was done. The mapped area (Area I) lies between UTM coordinates of Eastings (250000-252000) and Northings (9915000-9917000) in Nyakigyera sub county, Isingiro district. It borders Igaharo to the East and Kabingo to the South, and covers a total land area of four-square kilometers.
The area is underlain by rocks of Paleoproterozoic age that include granites, quartzites, shales, conglomerates and phyllites. In general, this Isingiro region and surrounding area areas belong to paleoproterozoic geology of Uganda under Rwenzori fold belt and this is where we find karagwe-Ankolean system of rocks in Uganda. The major structures encountered in this area includes joints, bedding planes, faults, folds and minor structures are quartz veins, crenulation cleavage. The Gayaza Synclinorium is a typical example of a cross fold with the axis plunging to the southwest at a small angle within the Karagwe-Ankolean rocks of SW Uganda. The fold is about 6km across and is preserved as a topographic high towering over the adjacent low-lying anticlines. The major structural trends are attributed to both Regional and Cross-folding oriented in the NW-SE and NE-SW directions.
The petrographic analysis of the thin sections indicates that most common minerals in the rocks are quartz, clay minerals and iron oxides. The metamorphism is largely regional metamorphism and generally of low grade. Contact metamorphism occurs in rocks adjacent to granitic intrusion. From rocks of very low grade in the synclinorium, a steep gradient is obvious towards large batholithic granites in the arena hence the metamorphism increases with stratigraphic depth and with proximity to the granite intrusions. | en_US |
