The Isingiro (Igayaza) area "A" field mapping excursion
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This report summarizes the findings made in the Geologic mapping project carried out in the Igayaza area, Isingiro district on the Igayaza-synclinorium, which is within the Karagwe-Ankolean system of rocks, South-Western Uganda. This course aimed at equipping students with skills of geologic mapping such as collecting field data, interpreting it and correctly representing it on a base map, collecting samples as well as acquiring knowledge on how to use field equipment such as GPS, geologic compass and so on. Field studies and analyses involved mainly traversing the mapping areas while collecting geo-data, collecting samples at specified noted locations laboratory analysis, and data analysis. While traversing the survey areas, rock descriptions were noted along with measurements like strikes, dips, and rock trends in general. The report is comprised of a detailed geological study for area “A” that was mapped; it covers the mineralogy, metamorphism, stratigraphy, structural data and economic activities as well as the regional synthesis which covers the Igayaza-synclinorium and surrounding areas within the Karagwe-Ankolean system. Area “A” is predominated by quartzite on top of the ridges, shale on the ridge slopes and valleys, as well as a few conglomerates. On addition to these, the rest of the Igayaza-synclinorium contains slates, mudstones, schists, phyllites and granites in the arena. The metamorphism of the Igayaza area is largely of low grade and the metamorphism grade increases towards the arena due to contact metamorphism resulting from granitic intrusion. Faulting and folding are the major tectonic events that occurred in this area and thus the common rock structures encountered are faults, joints, folds as well as bedding planes, laminations, boudinage and quartz veins. There are two major fold trends in this region; the regional set generally trending North-West which predominates and the cross fold set trending North-East. The Igayaza-Synclinorium is a cross fold with the axis plunging to the South-West. Weathering and erosion have also contributed greatly to the topography of this area such as the arena topography and the ridges. The drainage pattern of the area is essentially structurally controlled. The major economic activities in this area are cattle-keeping, farming in the fertile valleys and quarrying on the rock outcrops and exposures. Settlements are scarce and are in the valleys.