The Semliki Basin, Uganda : its sedimentation history and stratigraphy in relation to petroleum accumulation

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dc.contributor.advisorSmith, G Cen_ZA
dc.contributor.authorKiconco, Lyoidahen_ZA
dc.date.accessioned2014-10-21T06:51:14Z
dc.date.available2014-10-21T06:51:14Z
dc.date.issued2005en_ZA
dc.descriptionIncludes bibliographical references (leaves 140-147).en_ZA
dc.description.abstractThe Semliki Basin is covered by sediments that represent the Middle Miocene to Recent, which are described from outcrop and well data, underlain by possible Jurassic or Permo-Triassic to Early Tertiary sediments, which rest unconformably on Basement, described from seismic data. Thin-section analysis of selected samples, collected from the field, has shown that sandstones from the Semliki Basin are predominantly composed of quartz, potassium feldspars and plagioclase feldspars with subordinate clay minerals. Accessory minerals, such as micas (biotite and muscovite), heavy minerals, garnet and epidote, are present in minor amounts. This mineralogy indicates that the sediments have a granitic and gneissose origin, related to continental-block provenances. The X-ray diffraction scans of bulk samples reveal that the mudrocks/claystones are dominated by clay minerals with subordinate quartz, feldspars and calcite. The clay minerals include illite, illite-smectite, kaolinite, montmorillonite, illite-monnnorillonite, and mica with mixed layer illite-smectite and illite layers dominating. The clay minerals in the sediments were interpreted to be as a result of weathering of feldspars and volcaniclastic sediments. Authigenic minerals such as anatase and jarosite and secondary precipitates such as calcite and gypsum have also been interpreted as oxidation products of sulphides in the sediments. The study has allowed a better understanding of the stratigraphic relationship of the different rock units that are exposed on outcrop, those encountered in the wells, plus a section interpreted from seismic data. In general, the depositional environment of the sediments in the Semliki Basin is fluvial-lacustrine/deltaic showing significant variations in gamma-ray character, which reflect the water-level changes and river interactions through the depositional period and the influence of rifting tectonics on sediment deposition through time and space. The sediments in the Semliki Basin represent a petroleum play for hydrocarbon accumulations, in which the necessary elements of a valid petroleum system were identified. These include excellent or good potential for reservoirs and top seals as well as circumstantial evidence of regionally mature source rocks, possible seals, traps and hydrocarbon-migration pathways.en_ZA
dc.identifier.apacitationKiconco, L. (2005). <i>The Semliki Basin, Uganda : its sedimentation history and stratigraphy in relation to petroleum accumulation</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Geological Sciences. Retrieved from http://hdl.handle.net/11427/8656en_ZA
dc.identifier.chicagocitationKiconco, Lyoidah. <i>"The Semliki Basin, Uganda : its sedimentation history and stratigraphy in relation to petroleum accumulation."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 2005. http://hdl.handle.net/11427/8656en_ZA
dc.identifier.citationKiconco, L. 2005. The Semliki Basin, Uganda : its sedimentation history and stratigraphy in relation to petroleum accumulation. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Kiconco, Lyoidah AB - The Semliki Basin is covered by sediments that represent the Middle Miocene to Recent, which are described from outcrop and well data, underlain by possible Jurassic or Permo-Triassic to Early Tertiary sediments, which rest unconformably on Basement, described from seismic data. Thin-section analysis of selected samples, collected from the field, has shown that sandstones from the Semliki Basin are predominantly composed of quartz, potassium feldspars and plagioclase feldspars with subordinate clay minerals. Accessory minerals, such as micas (biotite and muscovite), heavy minerals, garnet and epidote, are present in minor amounts. This mineralogy indicates that the sediments have a granitic and gneissose origin, related to continental-block provenances. The X-ray diffraction scans of bulk samples reveal that the mudrocks/claystones are dominated by clay minerals with subordinate quartz, feldspars and calcite. The clay minerals include illite, illite-smectite, kaolinite, montmorillonite, illite-monnnorillonite, and mica with mixed layer illite-smectite and illite layers dominating. The clay minerals in the sediments were interpreted to be as a result of weathering of feldspars and volcaniclastic sediments. Authigenic minerals such as anatase and jarosite and secondary precipitates such as calcite and gypsum have also been interpreted as oxidation products of sulphides in the sediments. The study has allowed a better understanding of the stratigraphic relationship of the different rock units that are exposed on outcrop, those encountered in the wells, plus a section interpreted from seismic data. In general, the depositional environment of the sediments in the Semliki Basin is fluvial-lacustrine/deltaic showing significant variations in gamma-ray character, which reflect the water-level changes and river interactions through the depositional period and the influence of rifting tectonics on sediment deposition through time and space. The sediments in the Semliki Basin represent a petroleum play for hydrocarbon accumulations, in which the necessary elements of a valid petroleum system were identified. These include excellent or good potential for reservoirs and top seals as well as circumstantial evidence of regionally mature source rocks, possible seals, traps and hydrocarbon-migration pathways. DA - 2005 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2005 T1 - The Semliki Basin, Uganda : its sedimentation history and stratigraphy in relation to petroleum accumulation TI - The Semliki Basin, Uganda : its sedimentation history and stratigraphy in relation to petroleum accumulation UR - http://hdl.handle.net/11427/8656 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/8656
dc.identifier.vancouvercitationKiconco L. The Semliki Basin, Uganda : its sedimentation history and stratigraphy in relation to petroleum accumulation. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 2005 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/8656en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Geological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherGeologyen_ZA
dc.titleThe Semliki Basin, Uganda : its sedimentation history and stratigraphy in relation to petroleum accumulationen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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