- Title
- Evaluation of groundwater potential using neotectonics and geophysics in the context of post Karoo tectonic framework around Fort Beaufort and Smithfield, Eastern Cape, South Africa
- Creator
- Ndlovu, Nkosilathi
- Subject
- Neotectonics -- South Africa -- Eastern Cape Groundwater -- South Africa -- Eastern Cape Geophysical surveys -- South Africa -- Eastern Cape
- Date Issued
- 2017
- Date
- 2017
- Type
- Thesis
- Type
- Masters
- Type
- MSc
- Identifier
- http://hdl.handle.net/10353/12687
- Identifier
- vital:39299
- Description
- Geological and geophysical methods were used to investigate the Karoo area extending from longitudes 25.50 E to 27.50 E and latitudes 300 S to 330 S in South Africa, particularly Fort Beaufort, Aliwal North, Venterstad and Smithfield. The geology of the area is dominated by the upper Beaufort Group (Adelaide Subgroup) with an extensive network of dolerite sills and dykes that intruded the sedimentary sequence. A relationship between neotectonics, post-Karoo tectonics, groundwater and lithology was investigated to locate suitable groundwater potential sites. Apart from studying the role of neotectonics and the post Karoo tectonics, this research aims at generating groundwater targets to alleviate water shortages mainly for farming and livestock, and prove that neotectonics is still active. Methodologies adopted for obtaining these results included a comprehensive literature review, thin section analysis, scanning electron microscopy, geophysical investigation (magnetic, gravity, and vertical electrical sounding), and the application of Geographical Information Systems (GIS) and remote sensing. Twenty samples were collected at various locations within the study area and were analyzed using the petrographic microscope while others were analyzed with the Scanning Electron Microscopic (SEM) combined with an Energy dispersive x-ray spectrometry. The results show that the rocks are fractured, porous and have variable mineralogy (presence of heavy minerals) within the rocks. The use of Geographical Information Systems (GIS) and remote sensing in geological surveys, especially hydrogeology, has gained momentum over the past few years. This research is no exception as ArcMap software was used to create a map of seismic epicentres of the Eastern Cape Province. From the map it can be observed that seismicity still occurs and thus leading to the notion of neotectonics being active. Lineaments were also automatically extracted using the ENVI 5.1 and Geomatica 2013 software. Lineaments are zones of weakness in the subsurface of the Earth and are very important in locating groundwater potential sites. Geophysical techniques are essential and highly accurate for groundwater studies. Gravity and magnetic techniques were applied on data which was supplied as grids. Analysis using Geosoft Oasis 8.3 revealed extensive lineaments and ring like patterns and these were inferred to be dolerite intrusions (sills and dykes). The morphology of the intrusions help in identifying possible groundwater potential zones and thus they should be investigated. Vertical electrical sounding (VES) technique using the Schlumberger array was carried out at three sites (Fort Beaufort fracture which is possibly related to Quaternary surface uplift of the Amatole-Swaziland axis, splay of the Fort Beaufort fracture and at a site which showed high groundwater potential) to explore subsurface layering. IP2win (lite), 1-D modelling software was used to model the apparent resistivity data to obtain the geoelectric parameters of the subsurface (thickness and resistivity). The VES results are consistent with fractured rocks that aid groundwater movement. The VES data for the three sites was further modelled by the RES2DINV software and this shows low resistivity values associated with loose, water saturated top sandy soil and higher resistivity values associated with sedimentary sequences and dolerite. Moreover, potential sites for citing wells are predicted to be between 79.5 and 128 m on the profile. Further neotectonic studies need to be done, especially on the quaternary sediments as they would have more neotectonic evidence. The use of geophysical techniques for groundwater search need to be intensified, with more emphasis being put to the sedimentary sequences bordered by dolerite intrusions and fractured zones.
- Format
- 175 leaves
- Format
- Publisher
- University of Fort Hare
- Publisher
- Faculty of Science and Agriculture
- Language
- English
- Rights
- University of Fort Hare
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UFH Department of Geology
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | M Sc (Geology) NDLOVU.pdf | 13 MB | Adobe Acrobat PDF | View Details Download |