The Semiliki Basin Field Study Project Report
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This report details the observations made during the field excursion conducted from 2nd to 10th January 2022 and post-field data analysis and interpretation. The study was done in the Semliki Basin located within the Albertine Graben South and East of Lake Albert basin in Ntoroko District, Western Uganda. The Semliki basin is a rift basin and a half basin formed by tensional tectonics. The general stratigraphy of The Semliki basin consists of Kisegi, Kasande, Kakara, Oluka, Nyaburogo, Nyakabingo and Nyabusosi formations in that order. The fieldwork was carried out in areas of Kichwamba, behind Kisegi hill at the quarry, along seasonal the Kisegi River, along Kibuku road cut, and Sempaya hot springs. The main objective of the field work was to study the environment and processes of deposition of sediments and make deductions about the petroleum potential of the area. The specific objectives of the fieldwork were; to identify lithologies in the Semliki basin, to identify and relating structures observed in the basement and in the sediments, to identify different elements of the petroleum system and to identify the facies and depositional environments. Different materials like GPS, geologic compass used were to measure, record and store geological data. The manuals provided to each group were used to guide group members in the study process. Most of the activities done were in groups though some of the activities like presentation of results were individual work. Vast structural and stratigraphic data was collected and then analyzed to make conclusions about the petroleum potential of Semliki basin. The study area comprised of fluvial, deltaic and lacustrine sediments, all affected by intensive tectonic activity. This led to the formation of different structures with in the basement and sediments that we observed. Examples of these structures include faults, joints, folds, veins and banding. Sedimentary structures observed include cross bedding, unconformities, faults, and mud diapir and deformation bands. Mud diapirs, faults, plunging folds would be good structural seals. The presence of hot springs with in the area indicated the presence of a high geothermal gradient which is important factor for source rock maturation. Sedimentology, stratigraphy and tectonics are applied to develop a full understanding of the rocks and the sediments that fill Semliki sedimentary basin and this information was used to interpret the geologic history and evaluate the economic importance of these rocks. The general stratigraphy of The Semliki basin consists of Kisegi, Kasande, Kakara, Oluka, Nyaburogo, Nyakabingo and Nyabusosi formations in that order.