Semliki field study report in Karugutu Bundibugyo district

Abstract

The Semliki field study report includes interpretation of the stratigraphy, petrography, sedimentology and structural data of the Semliki basin field study in the Albertine graben area, Western Uganda at a small scale which is the major objective of the field study. The materials used have been explained in the introduction chapter while the methods used to achieve the main objective include lithological logging, describing outcrops then understanding of the metamorphism of the area and its effects on the rocks like foliations being more in the granitic gneiss near the amphibolite dyke at Kichwamba roadcut. The basement rock is exposed in this area which is overlain by sediments that are generally unconsolidated and these are; sands, clay, silts, conglomerates and the graded beds. These exhibit different structures which are attributed to the changes in the energy of the transporting media and each change in lithology suggests a different environment that is lacustrine for clay sediments and fluvial and deltaic for sand sediments which could be due to the regressive and transgressive episodes of lake Albert at the time of deposition. The Semliki basin is structurally wedge shaped and majorly comprises faults, joints, laminations and bedding planes, cross beds, foliations, unconformities, soft sediment deformation structures among others. The southern part of this basin has the highest elevation but the smallest thickness of accumulated sediments whereas the depocenter (5km thickness of sediments) is in the northern part of the Semliki basin. The sediments in the basin represent a petroleum play for hydrocarbon accumulations, in which the necessary elements of a valid petroleum system were identified as evidenced by the abundance of excellent reservoirs, regionally mature source rocks, traps, intraformational and regional seals as well as hydrocarbon-migration pathways in the basin.