Geological and stratigraphic field study of Kibuku (Semiliki) area in the Albertain Graben, Ntoroko District, Western Uganda
The area of study, Kibuku is found in Semliki basin located in the southern part of the Albertine graben (Ntoroko district), western Uganda. Semliki area lies onshore south of Lake Albert, it is bounded by the escarpment to the east and south and by rivers Lamia and Semliki to the west. It covers approximately 1200km². . The Albertine Graben lies on the western arm of the East Africa rift system with the rift flanks rising to approximately a height of 400m above the Graben on the eastern side. The rift flanks are underlined by the Basement Complex rocks such as granitic-gneisses, gneisses, amphibolites, schists, and quartzites which have undergone intense metamorphism. The field work and excursion study in the Albertine graben is conducted by students pursuing petroleum Geoscience and Production program during the recess term of third year under the guidance of our lecturers. The aim of this study was to enable us apply the geological, geophysical and other knowledge we have acquired during the course of the program to understand the geology, scrutinize and analyze the petroleum system of the area practically, also study the environments of deposition and the depositional processes that took place in the area. The Stratigraphy of the mapped Kibuku area comprises of fluvial and lacustrine deposits. The fluvial deposits include sand, conglomerates and thin layers of clays whereas the lacustrine deposits comprised of thick clay layers, mudstones and silt sediments. These sediment deposits have different types of bedding characteristics, nature of formation contacts, sedimentary structures and directional properties, textures, sorting, cementation, coloration, grain size and degree of consolidation. These differences are probably attributed to climatic changes, water discharge, sediment load, river mouth processes, waves, tides, currents, winds, slope together with the tectonics and geometry of the receiving basin The structures encountered include in syn-rift lithology include lamination, ripple marks, bedding (cross and graded beds), intra-sedimentary faults, Diapiric structures whereas for pre-rift lithology includes foliation, joints, faults.