The sedimentary petrology of carbonate nodules in the Elliot Formation, Karoo Supergroup, main Karoo Basin (South Africa)

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dc.contributor.advisorBordy, Emese Men_ZA
dc.contributor.authorMoodley, Adamen_ZA
dc.date.accessioned2016-07-14T12:20:28Z
dc.date.available2016-07-14T12:20:28Z
dc.date.issued2016en_ZA
dc.description.abstractIn South Africa, fossils found in the upper part of the Elliot Formation (Stormberg Group, Karoo Supergroup) are often associated with genetically poorly-constrained carbonate nodules. The origin of carbonate nodules i.e., pedogenic versus diagenetic, is important as pedogenic carbonate nodules can be used as palaeoclimate indicators, while diagenetic nodules carry limited palaeoclimatic information on the depositional setting. This research aims to characterize the carbonate nodules of the Elliot Formation macroscopically, petrographically and geochemically and to establish a diagnostic set of criteria to enable the differentiation between pedogenic and diagenetic nodules and/or diagenetic overprint. The research techniques employed in this study range from a) macroscopic field observations of the stratigraphic relationships of the nodules to the sedimentary features of the host rocks; b) sedimentary petrography of the textural features in the nodules; and c) X-ray diffraction for the assessment of the clay composition trapped within the nodules as compared to host rocks. Macroscopic field observations have shown that carbonate nodules found in the UEF are strongly associated with host rocks that contain pedogenic features such as root traces, burrows, colour mottling, and desiccation cracks, and thus are suggestive of ancient soils. However, the microscopic analysis of the nodules reveal no evidence for biological activities but rather a range of abiotic features such as septarian cracks, circumgranular cracks, and micronodules which are more likely have resulted from physicochemical processes that may have occurred during diagenesis. Clay minerals identified by X-ray diffraction include illite, muscovite, and montmorillonite confirm the generation of the sediments under arid to semi-arid climatic conditions.en_ZA
dc.identifier.apacitationMoodley, A. (2016). <i>The sedimentary petrology of carbonate nodules in the Elliot Formation, Karoo Supergroup, main Karoo Basin (South Africa)</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Geological Sciences. Retrieved from http://hdl.handle.net/11427/20345en_ZA
dc.identifier.chicagocitationMoodley, Adam. <i>"The sedimentary petrology of carbonate nodules in the Elliot Formation, Karoo Supergroup, main Karoo Basin (South Africa)."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 2016. http://hdl.handle.net/11427/20345en_ZA
dc.identifier.citationMoodley, A. 2016. The sedimentary petrology of carbonate nodules in the Elliot Formation, Karoo Supergroup, main Karoo Basin (South Africa). University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Moodley, Adam AB - In South Africa, fossils found in the upper part of the Elliot Formation (Stormberg Group, Karoo Supergroup) are often associated with genetically poorly-constrained carbonate nodules. The origin of carbonate nodules i.e., pedogenic versus diagenetic, is important as pedogenic carbonate nodules can be used as palaeoclimate indicators, while diagenetic nodules carry limited palaeoclimatic information on the depositional setting. This research aims to characterize the carbonate nodules of the Elliot Formation macroscopically, petrographically and geochemically and to establish a diagnostic set of criteria to enable the differentiation between pedogenic and diagenetic nodules and/or diagenetic overprint. The research techniques employed in this study range from a) macroscopic field observations of the stratigraphic relationships of the nodules to the sedimentary features of the host rocks; b) sedimentary petrography of the textural features in the nodules; and c) X-ray diffraction for the assessment of the clay composition trapped within the nodules as compared to host rocks. Macroscopic field observations have shown that carbonate nodules found in the UEF are strongly associated with host rocks that contain pedogenic features such as root traces, burrows, colour mottling, and desiccation cracks, and thus are suggestive of ancient soils. However, the microscopic analysis of the nodules reveal no evidence for biological activities but rather a range of abiotic features such as septarian cracks, circumgranular cracks, and micronodules which are more likely have resulted from physicochemical processes that may have occurred during diagenesis. Clay minerals identified by X-ray diffraction include illite, muscovite, and montmorillonite confirm the generation of the sediments under arid to semi-arid climatic conditions. DA - 2016 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2016 T1 - The sedimentary petrology of carbonate nodules in the Elliot Formation, Karoo Supergroup, main Karoo Basin (South Africa) TI - The sedimentary petrology of carbonate nodules in the Elliot Formation, Karoo Supergroup, main Karoo Basin (South Africa) UR - http://hdl.handle.net/11427/20345 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/20345
dc.identifier.vancouvercitationMoodley A. The sedimentary petrology of carbonate nodules in the Elliot Formation, Karoo Supergroup, main Karoo Basin (South Africa). [Thesis]. University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 2016 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/20345en_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 sedimentary petrology of carbonate nodules in the Elliot Formation, Karoo Supergroup, main Karoo Basin (South Africa)en_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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