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1
Oghenekome, Monica Enifome. "Sedimentary environments and provenance of the Balfour Formation (Beaufort Group) in the area between Bedford and Adelaide, Eastern Cape Province, South Africa." Thesis, University of Fort Hare, 2012. http://hdl.handle.net/10353/d1004354.
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The research examines the sedimentary environments and provenance of the Balfour Formation of the Beaufort Group (Karoo Supergroup) in the Eastern Cape Province, South Africa. This Formation occurs in the southeastern part of the Karoo Basin. It consists of sedimentary rocks, which are an alternating siltstone, shale and mudstone succession with subordinate interbedded sandstone and subsequently intruded by Karoo dolerite in the form of sills and dykes. ithostratigraphically, the Balfour Formation is subdivided into five units namely, from the base to the top, the Oudeberg, Daggaboersnek, Barberskrans, Elandsberg and Palingkloof Members. The Balfour Formation is overlain by the Katberg Formation. This study involved field investigations in the vicinity of the towns of Bedford and Adelaide with integrated stratigraphical, sedimentological and petrological studies. A geological map was constructed after field investigations. Lithofacies of the Balfour Formation that were studied are characterised by sandstone facies (Sh, Sm, St, Sr, Sp) and fine-grained sediments (Fl or Fsm) which reflect point-bar, cut-bank, channel and floodplain deposits. Lithologically, the Oudeberg Member consists of sandstone of which some units are internally massive alternating with thin laminated siltstone and mudstone. The Daggaboersnek Member is characterised by regular, generally non-lenticular, overall stratification, in the Barberkrans Member consists of sandstone lithosomes, while the Elandsberg Member is an argillaceous unit, similar to the Daggaboersnek Member. The Palingkloof Member is composed predominantly of red mudstone that can be used to distinguish the Balfour Formation from the overlying Katberg Formation, which consists predominantly of sandstone. The stratigraphic sequence displays two fining upward megacycles of sedimentary deposits with change in the sediment supply pattern from low-sinuosity to high-sinuosity river systems which reflect both braid and meandering deposits, respectively. Sedimentary structures in the sandstone units and the provenance of the Balfour Formation indicate that these deposits were produced by rivers flowing from the southeast with minor drift towards the northwest. According to the composition of the sediments and their sequence of deposition the Formation represents a fluvial environment. Mineralogical and grain size data from the sandstones of the various members of the Balfour Formation indicate the same source area of granitic, metamorphic and older sedimentary rocks and show no significant petrographic differences. The petrographic and geochemical investigations confirmed the sandstone to be feldspathic litharenite and ultralithofeldspathic sandstone. The palaeocurrent investigation indicates the main provenance to have been situated to the southeast of the Karoo basin. Heavy-mineral concentrations within the sandstones also give an indication that the source had a transitional arc plate tectonic setting.
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Dewey, Felicity Joy. "The sedimentology and palaeoenvironmental significance of vlei sediments on the Winterberg range, South Africa." Thesis, Rhodes University, 1989. http://hdl.handle.net/10962/d1001897.
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Palaeoenvironmental reconstruction of the late Pleistocene and Holocene geological periods for central and southern Africa has been hampered by the erratic distribution of suitable sites, incomplete and inaccurately dated sequences and the limited nature of published data. One geomorphological feature which has supplied valuable evidence for fluctuations in past environmental conditions, is the vlei or dambo. The type-site of these waterlogged features is in south central Africa, but similar features have been described on other continents. The clastic and organic sediments contained within these features are affected by, and therefore reflect to some degree, the environment under which they were formed. The characteristics of the sediments supply information as to their transport and mechanisms of deposition. From these processes, the environmental conditions at the time of vlei formation can be inferred. The environmental history of the Eastern Cape region has been considerably neglected, and is far less well understood than other countries such as Malawi, Zambia and Zimbabwe. A study site in the Winterberg Range (Eastern Cape) was selected which permitted the comparison of two vleis, the objective being to establish an accurate late Pleistocene sediment chronology for the entire plateau area. Radiocarbon dates from organic layers indicate that these sediments span the last 12 000 years BP, suggesting that organic accumulation at this site began at roughly the same time as at sites further afield. The vlei sediments are analysed in terms of their morphology, particle slze distribution, and other physical and chemical characteristics. These data facilitate the construction of detailed stratigraphic diagrams and a chronological summary of sediment accumulation, from which the period and governing processes of vlei development under changing environments may be described. It is found that the Winterberg vleis contain sediments which respond to changes in the prevailing environment. This makes these sediments useful indices from which to trace such changes during the late Pleistocene and Holocene times. These features are found to be similar in many respects to those described elsewhere in Southern Africa. The study attempts to provide greater understanding of contemporary vlei processes and emphasises the necessity of their preservation, as finite and valuable resources, by future generations
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Fraser, Nicholas Tweedie. "A Metamorphic Study of Pretoria Group Sediments Found at the Dwarsrivier Pass, Bushveld Igneous Complex, South Africa." Diss., University of Pretoria, 2019. http://hdl.handle.net/2263/76009.
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The study takes place in the Dwarsrivier area which lies on the border between Mpumalanga and Limpopo, to the North-West of Lydenberg, at an exposed road cutting. Within the road cutting, there is a unique portion of exposed rock which is light in colour and identified as a calc-silicate. The calc-silicate material is present as a package of rock and is surrounded top and bottom by pyroxenite. The surrounding rock belongs to the Bushveld Igneous Complex (BIC), which is the largest known layered intrusion on the planet and is host to numerous mines. The sample area is within the Critical Zone of the BIC and the host rock consists of pyroxenite which is crystalline and mafic. The calc-silicate package originates from the Pretoria Group sediments, which hosts the BIC, and has undergone varying degrees of metamorphism and mineralisation. The metamorphism formed and allowed for the preservation of two rare minerals, namely wüstite and chlorospinel. Numerous tests were performed on the samples, including SEM point scans to identify these rare minerals and to better understand how the calc-silicate package was preserved in the BIC. A model was created to explain the occurrence of the calc-silicate slab and surrounding features. The previous model involved the slab rising up through the BIC, but the proposed model in this thesis is that the calc-silicate was part of the roof rock which then delaminated, and subducting into the ductile magma of the BIC.Dissertation (MSc)--University of Pretoria, 2019.
Geology
MSc
Unrestricted
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Ojongokpoko, Hanson Mbi. "Porosity and permeability distribution in the deep marine play of the central Bredasdorp Basin, Block 9, offshore South Africa." Thesis, University of the Western Cape, 2006. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_1341_1189600798.
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This study described porosity and permeability distribution in the deep marine play of the central Bredasdorp Basin, Block 9, offshore South Africa using methods that include thin section petrography, X-ray diffraction, and scanning electron microscopy, in order to characterize their porosity and permeability distributions, cementation and clay types that affect the porosity and permeability distribution. The study included core samples from nine wells taken from selected depths within the Basin.
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Chere, Naledi. "Sedimentological and geochemical investigations on borehole cores of the Lower Ecca Group black shales, for their gas potential : Karoo basin, South Africa." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/d1021201.
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In the recent years, the shale gas discourse has become central to discussions about future energy supply in South Africa. In particular, the Permian black shales of the Lower Ecca Group formations in the Karoo Basin are considered potential source rocks for shale gas. The research presented in this thesis advances the understanding of the shale gas potential of mainly the Prince Albert, Whitehill and Tierberg/Collingham Formations. These shale sequences were sampled from eight deep boreholes spread across the main Karoo Basin and geochemically analysed at the GFZ - Helmholtz Centre Potsdam, Germany. Three key questions guided the study, these are: (i) what is the lithology of the sequence; (ii) where in the basin do the shale sequences attain maximum thickness at optimum depth i.e. beneath 1000-1500m; and (iii) and their shale characteristics. To evaluate these, borehole core logging, petrology and organic geochemistry were used extensively. Petrology involved the use of thin section, scanned electron and transmission electron microscopy for mineralogy as well as the identification of sedimentary features, organic matter and nano-scale porosity. These were coupled with standard organic geochemistry techniques such as Rock Eval. analysis, open pyrolysis gas chromatography and thermovaporisation to quantify the free gas, total organic carbon (TOC), present-day gas generative potential and kerogen type. The results show that the Whitehill Formation, away from the CFB and not intruded by dolerite, has the most potential for shale gas. Microscopic studies of this pyritic black shale reveal the occurrence of porous amorphous matter, indicating thermal maturity within the gas generation zone (i.e. > 1.1 percent Ro, 120ºC). The TOC content is consistently high within the Whitehill (exceeding industry requirement of 2 percent), attaining maximum of 7.3 percent. The highest yields of free and desorbed gas, especially methane, were emitted within this formation (S1 and nC1 peaks); mostly within its dolomitic units. In addition, dissolution porosity within dolomite units of the Whitehill Formation was identified as the predominant type of porosity. Thus, it is deduced that the dolomitic units of Whitehill Formation potentially contain the greatest volumes of free gas. HI values attain maximum of 25 mg HC/g TOC, whereas the OI values 26 mg CO2/g TOC. Such low HI and OI values are typically attributed to the dominance of Type IV kerogen, and consistent with overmaturity. Open pyrolysis (GC) show the main the chemical compound of the organic matter to be m-p-xylene, consistent with a mix of Type III, Type I/II and Type IV kerogen. Lithologically, the Whitehill Formation is composed of ~ 35 quartz, 13 percent feldspar, 26 percent illite and ~ 23 percent dolomite with variable amounts of pyrite. The dominance of quartz is directly proportional to the brittleness of the rock. Thus it can be deduced that the Whitehill Formation is relatively brittle and therefore fraccable. Burial trends indicate increasing depth (from ground level) to the top of the Whitehill Formation towards the south and south-eastern portion of the basin. It is in the southern region where thicknesses of this black shale exceeding 50m occur at depths more than 1500m; 1000m beneath fresh water aquifers. It therefore concluded that Whitehill Formation in the southern portion of Karoo Basin, but away from the thermo-tectonic overprint of the Cape Orogeny, is the most probable shale gas reservoir in South Africa.
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Baiyegunhi, Christopher. "Sedimentary, geochemical and geophysical study of the Ecca group, Karoo supergroup and its hydrocarbon potential in the Eastern Cape Province, South Africa." Thesis, University of Fort Hare, 2017. http://hdl.handle.net/10353/4881.
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The Ecca Group of Karoo Supergroup is a sedimentary rock sequence that deposited between the Late Carboniferous (Dwyka Group) and the Late Permian-Middle Triassic (Beaufort Group). The Ecca Group investigated in this study is situated in the Eastern Cape Province of South Africa and it comprises mainly of shales, mudstones, siltstones and sandstones. The Ecca Group sequence contains considerable carbon content and suitable thickness to make it an ideal target for shale gas exploration. Previous studies put more emphasis on the geology and stratigraphy of the Ecca Group, this study revised the stratigraphy, and put new insight on the petrography, depositional processes, sedimentary facies, provenance, paleoweathering, tectonic setting, subsidence rates and history, electrical resistivity, source rock characteristics and diagenesis of the potentially feasible sandstone and mudrock reservoir rocks of the Ecca Group. Based on the lithological features, sedimentary structures and facies characteristics, the stratigraphy of the Prince Albert, Whitehill, Collingham and Fort Brown Formations of the Ecca Group is now subdivided into two informal members each, i.e. Lower Member and Upper Member. Furthermore, the Ripon Formation is now subdivided into three informal members. Each member has been asigned a lithological name. The grain size parameters show that most of the Ecca Group sandstones are very fine to fine grained, poorly to moderately well sorted, mostly near-symmetrical and mesokurtic in grain-size distribution. The linear discriminant function analysis is dominantly indicative of turbidity current deposits under deep marine environment for Prince Albert, Whitehill and Collingham Formations, shallow marine environment for Ripon Formation, while the Fort Brown Formation is lacustrine-deltaic deposits. Modal composition analysis and petrography studies revealed that the detrital components of the sandstones are dominated by monocrystalline quartz, feldspar and lithic fragments. The sandstones are compositionally and texturally immature and can be classified as feldspathic wacke and lithic wacke. The provenance analysis revealed plutonic and metamorphic terrains as the main source rocks with minor debris derived from recycled sedimentary rocks. The detrital modal compositions of these sandstones are related to back arc to island and continental margin of tectonic setting. Based on the detailed sedimentological analyses of outcrop and borehole data, fourteen lithofacies were identified and seven facies associations (FAs) were recognised. The facies associations are: FA 1: Shale and mudstones intercalated with siltstones, FA 2: Carbonaceous shale, mudstone with subordinate chert and sandstone, FA 3: Mudstones rhythmite with thin bedded mudstone and lenticular siltstone, FA 4: Greyish medium bedded sandstone intercalated with laminated mudstone, FA 5: Dark-grey medium to thick bedded mudstone and siltstone, FA 6: Thin to medium bedded sandstone alternated with thin bedded carbonaceous mudstone, and FA 7: Varved mudstone rhythmite intercalated with siltstone and minor sandstone. Sedimentological characteristics of the identified facies associations indicate four deposition environments, namely, deep marine basin, turbidite, shallow marine and lacustrine environments, which constitute a gradually regression sequence as a result of sea-level dropping and shallowing of the basin during the developmental processes. Geochemical analysis of the Ecca mudrocks and sandstones revealed that the rocks are of quartzose sedimentary provenance, suggesting that they were derived from a cratonic interior or recycled orogen. The petrography and geochemistry of the sandstones indicated that the source areas are composed of plutonic and metamorphic rocks with a minor component from sedimentary rocks. The geochemical diagrams and indices of weathering suggested that the granitic source rocks underwent moderate to high degree of chemical weathering. The tectonic setting discrimination diagrams support passive continental margin setting of the provenance.
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Olajide, Oluseyi. "The petrophysical analysis and evaluation of hydrocarbon potential of sandstone units in the Bredasdorp Central Basin." Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_9559_1181561577.
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This research was aimed at employing the broad use of petrophysical analysis and reservoir modelling techniques to explore the petroleum resources in the sandstone units of deep marine play in the Bredasdorp Basin.
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Pienaar, Marc. "Dating the stone age at Rose Cottage Cave South Africa : an exercise in optically dating cave sediments." Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-06052007-084723.
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Megner-Allogo, Alain-Cedrique. "Sedimentology and stratigraphy of deep-water reservoirs in the 9A to 14A Sequences of the central Bredasdorp Basin, offshore South Africa." Thesis, Stellenbosch : Stellenbosch University, 2006. http://hdl.handle.net/10019.1/17400.
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Thesis (MSc)--University of Stellenbosch, 2006.ENGLISH ABSTRACT: The Barremian to Albian siliciclastic deep-water deposits of the central Bredasdorp Basin were investigated primarily in terms of their stratigraphic evolution, depositional characteristics and facies distribution. Cores from the deep-water deposits reveal that the facies successions are composed of massive, ripple cross- to parallel-laminated sandstones, conglomerate, massive claystone, alternating laminated to interbedded sandstone/siltstone and claystone, laminated and clay-rich siltstone. These facies are grouped into channel-fill, sheet-lobe, overbank and basin plain deposits, by inference. The application of sequence stratigraphy, based on gamma ray and resistivity log patterns, reveals that all 3rd-order depositional sequences comprise 4thorder cycles. The latter are subdivided into three components (lowstand, transgressive and highstand systems tracts), based on vertical facies changes and internal stratigraphic key surfaces. Taking the 13Amfs as the stratigraphic datum for each well, correlation was possible on a regional basis. Lowstand deposits, comprising thick amalgamated massive sandstones, were interpreted to represent channelfills. Their vertical and horizontal stacking forms channel-fill complexes above Type 1 unconformities. Adjacent thin-bedded intervals, comprising parallel- to ripple cross-laminated sandstones, were interpreted as levee/overbank deposits, whereas clay-rich intervals were interpreted to represent basin plain deposits of hemipelagic origin. Facies associations and their distribution have revealed that channel-fills are associated with overflow deposits and sheet sand units. These deposits, as well as downdip sheet sands associated with small channel-fills within the 9A, 11A/12A, 13A Sequences and the 14A Sequence were interpreted to have been deposited in a middle fan to upper fan setting. A similar association occurs in the 10A Sequence, except that thick conglomerate units are present at the base of proximal channel-fills. This led to interpret the 10A Sequence as being deposited in a base-of-slope to upper fan setting. The thickness of each sequence, as revealed by isochore maps, shows sinuous axial flow path which corresponds to channel-fill conduit. The continuous decrease of this sinuosity upward in the succession was interpreted as being related to basin floor control along the main sand fairways. Successive flows result in erosion-fill-spill processes, which locally favour connectivity of reservoirs over large areas. Recognition of higher-order sequences and key stratigraphic surfaces helps to understand internal stratigraphic relationships and reveals a complex and dynamic depositional history for 3rd-order sequences. However, sparse well control and uneven distribution of boreholes, as well as lack of seismic and other data, limited the models derived for this study.
AFRIKAANSE OPSOMMING: Die Barremiaanse tot Albiaanse silisiklastiese diepwater afsettings van die sentrale Bredasdorp Kom is hoofsaaklik in terme van stratigrafiese evolusie, afsettingskarakteristieke en fasies distribusie ondersoek. Kerne van die diepwater afsettings toon dat die fasies opeenvolgings uit massiewe, riffelkruis- tot parallel-gelamineerde sandstene, konglomerate, massiewe kleistene, afwisselende gelamineerde tot intergelaagde sandstene/slikstene en kleistene, sowel as gelamineerde en klei-ryke slikstene bestaan. Hierdie fasies word onderverdeel in kanaalopvulsel, plaatlob, oewerwal en komvlakte afsettings. Die toepassing van opeenvolgingsstratigrafie gebaseer op gammastraal en resistiwiteit log patrone toon dat alle 3de-orde afsettingsopeenvolgings uit 4deorde siklusse bestaan. Laasgenoemde word onderverdeel in drie komponente (lae-stand, transgressie en hoë-stand sisteemgedeeltes), gebaseer op vertikale fasies veranderinge en interne stratigrafiese sleutel vlakke. Korrelasie op ‘n regionale basis is moontlik gemaak deur die 13Amfs as die stratigrafiese verwysing vir elke boorgat te neem. Lae-stand afsettings, wat uit dik saamgevoegde massiewe sandstene bestaan, word geïnterpreteer as kanaalopvulsels. Die vertikale en horisontale stapeling van die sandstene vorm kanaalopvulsel komplekse bo Tipe 1 diskordansies. Naasliggende dungelaagde intervalle, wat uit parallel- tot kruisgelaagde sandstene bestaan, word geïnterpreteer as oewerwal afsettings, terwyl klei-ryke intervalle geïnterpreteer word as verteenwoordigend van komvlakte afsettings van hemipelagiese oorsprong. Fasies assosiasies en hul verspreiding toon dat kanaalvul geassosieër word met oorvloei afsettings en plaatsand eenhede. Hierdie afsettings, sowel as distale plaatsande geassosieër met klein kanaalopvulsels binne die 9A, 11A/12A, 13A en die 14A Opeenvolgings, word geïnterpreteer as afgeset in ‘n middelwaaier tot bo-waaier omgewing. ‘n Soortgelyke assosiasie bestaan in die 10A Opeenvolging, behalwe dat dik konglomeraat eenhede teenwoordig is by die basis van proksimale kanaalopvullings. Dit het gelei tot die interpretasie van die 10A Opeenvolging as afgeset in ‘n basis-van-helling tot bo-waaier omgewing. Die dikte van elke opeenvolging, soos verkry vanaf isochoor kaarte, toon ‘n kronkelende aksiale vloeipad wat ooreenkom met ‘n kanaalopvulling toevoerkanaal. Die aaneenlopende afname van hierdie kronkeling na bo in die opeenvolging word geïnterpreteer as verwant aan komvloer-beheer langs die hoof sand roetes. Opeenvolgende vloeie veroorsaak erosie-opvul-oorspoel prosesse, wat lokaal die konnektiwiteit van reservoirs oor groot areas bevoordeel. Herkenning van hoër-orde opeenvolgings en sleutel stratigrafiese vlakke dra by tot ‘n goeie begrip van die interne stratigrafiese verhoudings en ontbloot ‘n komplekse en dinamiese afsettingsgeskiedenis vir 3de-orde opeenvolgings. Beperkte boorgatbeheer en ‘n tekort aan seismiese en ander data het egter ‘n beperkende rol gespeel in die daarstel van modelle vir hierdie studie.
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Mahed, Gaathier. "Analysis of temporal and spatial variations in water storage by means of gravimetric and hydrologic methods in the region around the South African gravimetric observation station." Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/6714.
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This work examines the use of gravity data and its application to subsurface water reservoirs in the immediate vicinity of the South African Geodynamic Observatory, Sutherland (SAGOS), situated in a semi-arid region of the Karoo region of South Africa, and underlain by the Karoo sedimentary rocks intruded by dolerite dykes and sills. SAGOS houses the only supergravity metre (SG) in Africa, and this thesis sets out to test its use in monitoring groundwater dynamics using hydrological and gravity data. The main aim of this work is the application of the SG data, in conjunction with hydrological data, to better understand episodic recharge of subsurface reservoirs. The importance of water as a resource, globally and specifically the Karoo, is reviewed in conjunction with supply and demand of water. This is to contextualise the socio-economic, technical as well as policy issues related to water resource management. Applicable technologies for water resource management and efficient water use are highlighted and the application of gravity to hydrology is introduced, including satellite as well as ground based tools. In addition, arid zone hydrology as well as recharge and its mechanisms are analysed in order to better understand these processes when examined from gravity measurements. Issues related to understanding flow within the vadose zone as well as in secondary aquifers are examined, and gravity residuals and subsurface hydrology are highlighted. Thereafter, a conceptual groundwater flow modelof the study area is developed using multiple tools. First, the geology around SAGOS was mapped using SPOT 5 imagery and then ground truthed. Second, stable isotopes and water chemistry analysis was undertaken on water samples from selected boreholes. The results allude to preferential flow acting as the main mechanism for groundwater recharge. Follow-up pump-tests illustrate that fracture connectivity is greatest at close proximity to the dyke. Soil mapping, using aerial photography was also undertaken. Duplex soils, enriched with clay at depth, dominate the study area. Using in-situ infiltration tests, it is shown that the alluvium, which lines the river beds, has a higher hydraulic conductivity than the other soils, confirming that these streams act as preferential conduits for subsurface recharge. Precipitation events were correlated against gravity residuals at 4 wells, over different time periods. The results are examined using time series analyses. Gravity residuals from well SA BK07, over a period of 24 hours after the rainfall event, delineate instances of negative correlations, as well as strong positive correlations (of up to 0.9). On the whole however, correlations between gravity and groundwater at SA BK07 are variable and weak, and in conjunction with water level measurements and water chemistry, the data suggest that this well is located in a dynamic conduit (throughflow) and not in a permanent groundwater reservoir. By contrast, other wells show strong positive correlations between gravity residuals and water levels following episodic recharge events for a later time series. Correlations between the water levels and gravity residuals in wells SA BK04, SA BK05 and SA BK 01 are in excess of 0.7 for specific rainfall events. In summary, the results suggests that gravity is an excellent tool for measuring episodic groundwater recharge within the immediate vicinity of the SAGOS. This implies that gravity can aid in monitoring groundwater losses/gains in arid and semi-arid areas. Recommendations for future work are highlighted at the end; these include the possible use of hydrological modelling of reservoirs at various scales and then comparing these results to the SG as well as GOCE and GRACE satellites data, and then improving numerical modelling of the groundwater dynamics for sites like Sutherland and the surrounding arid Karoo region, where sparse water shortages, and potential pollution related to fracking for shale-gas, are likely to compete with established water needs for farming and human consumption. It is also suggested that the gravity modelling be examined to better understand site specific scenarios and thus aid in improving the processing of the gravity signal.
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Shaw, Alexander Iain. "The characterisation of calcrete based on its environmental settings within selected regions of the Kalahari, Southern Africa." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:3474d9e4-fa10-4bd4-af7e-dcbe9ebad640.
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Chemical sediments in a variety of geomorphic environments (pedogenic, fluvial, palustrine, lacustrine and pan) were investigated from seven regions (SW Kalahari, Kgalagadi, Kalkweissrand, Etosha, Linyanti, Okavango and Ngami) in the Kalahari of southern Africa. These primary and multi-phase sediments were characterised by a range of pure and intergrade silcrete, calcrete and dolocrete fabrics which contained an array of structures indicative of the crystalline and biogenic processes responsible for their precipitation, epigenesis and paragenesis. Petrography, mineralogy and isotope geochemistry provided significant insight regarding the environmental and geochemical conditions at the time of precipitation. Petrography indicated that the majority of chemical sediments were undergoing epigenetic modification as a consequence of the desiccation induced transition from phreatic to vadose diagenetic and geochemical conditions. The role of rapidly infiltrating meteoric water, associated with unstable wetting fronts, is believed to be instrumental in vadose diagenesis and the precipitation of crystalline/alpha fabric carbonate. Salinisation within the capillary fringe and deeper vadose zone is believed to be responsible for the sequence dolomitisation of crystalline calcite within mature sequences. Highly saline pan conditions instigate the precipitation of authigenic dolomite, calcite and K-feldspar within the surface sediments and authigenic silica at depth. Phreatic water beneath the islands, floodplains and fluvial systems of the Okavango, which undergoes evapotranspirational and transmission salinisation and ultimately terminal desiccation, are similarly precipitating silcrete. Pedogenic processes principally associated with C4 vegetation are responsible for the gratification of carbonate mud within desiccating lacustrine, palustrine and pan sediments. Within the thin sandy Kalahari soils, pedogenesis is limited, but biogenic/beta fabric precipitation linked to mycorrihizae and tree/shrub savanna vegetation is instrumental in the formation of hardpans and the modification of upper calcrete horizons. The dominance of a distinct assemblage (smectite/kaolinite or sepiolite/palygorskite) of authigenic clay minerals present within all the environments provides evidence of semi-arid precipitation within Mg and Ca enriched saline/rapidly evaporating water or brackish/reduced permeability environments.
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Ntombela, Nondumiso. "A 3D fault seal analysis study conducted in the Ibhubesi Gas Field Offshore the West Coast of South Africa." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/27833.
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A three dimensional fault seal analysis study of the AK fault situated offshore of the West Coast of South Africa is presented. This study is aimed at informing the development plan of the Ibhubesi gas field with regards to the compartmentalization of the reservoirs, by understanding whether a key fault, the AK fault facilitates hydrocarbon migration to the Ibhubesi field reservoirs or whether it provides a seal. In order to address this research aim, a seismic interpretation of the area was carried out and combined with an interpretation of well data to construct a 3D structural model from which the fault seal analysis was carried out. Juxtaposition analysis was used to determine the lithologies that had been juxtaposed across the fault. Fault clay was determined using the Shale Gouge Ratio (SGR) algorithm and permeability and threshold pressure were also used to quantify the fault seal capacity. The results from the SGR were correlated to the across fault pressure difference and plotted on a reference diagram which is a comparison of sealing faults vs. leaking faults. This diagram indicates that faults with an SGR greater than 25% and threshold pressures greater than 8bars, have a high potential to seal. The AK fault SGR results range between 25 and 55 % with a threshold pressure of up to 20bars. These results indicate that the AK fault is likely to be a sealing fault.
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Le, Roux F. G. "The lithostratigraphy of Cenozoic deposits along the south-east Cape coast as related to sea-level changes." Thesis, Stellenbosch : Stellenbosch University, 1989. http://hdl.handle.net/10019.1/67134.
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Thesis (MSc)--University of Stellenbosch, 1989.AFRIKAANSE OPSOMMING: Senosoiese sedimente langs die suidooskus van die Kaapprovinsie is periodiek deur verskeie outeurs vir meer as 'n eeu bestudeer. In hierdie aanbieding word die Iiteratuur saamgevat en vele dubbelsinnige stratigrafiese onderverdelings en definisies opgeklaar. Die Senosoiese afsettings kan volgens oorsprong geklassifiseer word as marien, eolies en fluviaal. Die mariene afsettings, synde strand-, nabystrand-, estuarien of lagunale afsettings geassosieerd met transgressiewe/ regressiewe kusIyne, word nou op grond van kenmerkende litologiese, paleontologiese sowel as ouderdomsverskille onderverdeel in die Paleogeen Bathurst, Neogeen Alexandria en Kwaternere Salnova Foraasies. Die Laat-Plioseen tot Vroeg-Pleistoseen Nanaga Formasie, Middel- tot Laat- Pleistoseen Nahoon Formasie en die Holoseen Schel• Hoek Formasie vorm die kus-eoliese afsettings. AI die mariene en marienverwante (eoliese} formasies, gekenmerk deur kalkige klastiese afsettings, is saamgegroepeer in 'n nuutgedefinieerde Algoa Groep. Fluviale afsettings word onderverdeel in die Martindale, Kinkelbos, Bluewater Bay, Kudus Kloof en Sunland Formasies. Die onderskeie afsettings word gekorreleer met verskillende seevlakstande deur geologiese tye. Die vroegste Senosoiese transgressiewe/regressiewe siklus het in die Vroeg-Paleoseen begin en die hoogste aangetekende elevasie vir die era bereik. Die Bathurst Formasie is waarskynlik gedurende hierdie regressie afgeset. 'n Tweed~ kleiner transgressie/ regressiesiklus het plaasgevind gedurende die Laat-Eoseen tot Vroeg-Oligoseen. Sover tans bekend, kan geen afsetting in die dagsoomgebied van die Algoa Groep definitief met hierdie siklus in verband gebring word nie. Die volgende siklus, wat 'n transgressiewe maksimum van c. 250 m bereik het, het begin in die Middel-Mioseen en verstryk in die Vroee Plioseen. Mariene planasie van die kusplatform het gedurende die transgressie plaasgevind terwyl die Alexandria Formasie wat tans bo 120 m geleë is, gedurende die regressie afgeset is. Die Vroeg-Plioseen transgressie het waarskynlik 'n maksimum huidige hoogte van c. 120 m bereik, waartydens o.a. die 120 m branderstoep en "Humansdorpterras" gekerf is. Die Alexandria Formasie tans geleë tussen 60 en 120 m, is afgeset gedurende die Laat-Plioseen regressie. Hierdie regressie het verskeie relatief lang stilstande, wat waarskynlik die 106-m, 90- tot 100-m en 84-m branderstoepe verklaar, ondervind. Selfs die 60-m en 52-m kuslyne kon tydens hierdie regressie gevorm het. Voorlopige paleontologiese getuienis dui egter daarop dat die 60-m kuslyn 'n transgressiewe maksimum van 'n daaropvolgende siklus verteenwoordig, gevolg deur 'n regressie met minstens een beduidende stilstand by 52 m. Die Alexandria Formasie geleë tussen c. 60 en 30 m, is waarskynlik gedurende hierdie regressie gedeponeer, waartydens ook die Bluewater Bay, Kinkelbos en Kudus Kloof Formasies afgeset is. Gedurende die Kwaternêre transgressie/regressiesiklusse, waarvan minstens vier aangedui word, is die Salnova Formasie (afwesig bo 30 m) afgeset. Die Nahoon Formasie, wat ook op groot skaal op die kontinentale bank ontwikkel is, is gedeponeer gedurende die laaste twee Pleistoseen glasiale toe seevlakke tot benede -100 m gedaal het. Die Schelm Hoek Formasie wat tans nog afgeset word, het ontstaan uit die transgressiewe maksimum van die Flandriese transgressie aan die begin van die Holoseen.
ENGLISH ABSTRACT: Cenozoic sediments along the south-east coast of the Cape Province have been studied intermittently for more than a century by various authors. In this presentation the literature is reviewed and many ambiguous stratigraphic subdivisions and definitions are clarified. The Cenozoic deposits can be classified, according to origin, as marine, aeolian and fluvial. The marine deposits, being lagoonal deposits either beach, nearshore, estuarine or associated with transgressive/regressive shorelines, are now subdivided on the grounds of distinct lithological, palaeontological as well as age differences into the Palaeogene Bathurst, Neogene Alexandria and Quaternary Salnova Formations. The Late Pliocene to Early Pleistocene Nanaga Formation, the Hiddle to Late Pleistocene Nahoon Formation and the Holocene Schelm Hoek Formation constitute the coastal and marine-related aeolian deposits. All the marine (aeolian) formations, which are characterised by calcareous clastics, have been grouped together in a newly defined Algoa Group. Fluvial deposits are subdivided into the Martindale, Kinkelbos, Bluewater Bay, Kudus Kloof and Sunland Formations. The various deposits are correlated with different stands of sea-level through geological time. The earliest Cenozoic transgression/regression cycle started in the Early Palaeocene and reached the highest recorded altitude for the era. The Bathurst Formation was probably deposited during this regression. A second lesser transgression/regression cycle occurred in the Late Eocene to Early Oligocene. As far as is presently known, no deposit in the outcrop area of the Algoa Group can be definitely related to this cycle. The next cycle, which reached a transgressive maximum of c. 250 m, started in the Middle Miocene and terminated in the Early Pliocene. Marine planation of the coastal platform took place during the transgression, whilst the Alexandria Formation presently situated above 120 m, was deposited during the regression. The Early Pliocene transgression is considered to have reached a maximum present-day elevation of c. 120 m, during which the 120 m marine bench and "Humansdorp Terrace", amongst others, were carved. The Alexandria Formation presently situated between 60 and 120 m, was deposited during the Late Pliocene regression, which experienced several relatively long stillstands which probably account for the 106 m, 90 t.o 100 m and 8.4 m benches. Even the 60 m- and 52 m-shorelines could have been formed during this regression. Preliminary palaeontological evidence, however, suggests that the 60 m shoreline represents a transgressive maximum of a subsequent cycle followed by a regression with at least one significant stillstand at 52 m. The Alexandria Formation situated between c. 60 and 30 m, was probably deposited during this regression, which also saw the deposition of the Bluewater Bay, Kinkelbos and Kudus Kloof Formations. During the Quaternary transgression/regression cycles, of which at least four are indicated, the Salnova Formation (absent above 30 m) was deposited. The Nahoon Formation, which is also extensively developed on the continental shelf, was deposited during the last two Pleistocene glacials, when sea-levels receded to less than -100 m. The Schelm Hoek Formation, which is still being deposited, originated from the transgressive maximum of the Flandrian transgression at the start of the Holocene.
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Van, Eeden Johan. "Basin analysis and sequence stratigraphy a review, with a short account of its applicability and utility for the exploration of auriferous placers in the Witwatersrand Basin." Thesis, Rhodes University, 1996. http://hdl.handle.net/10962/d1005546.
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The Witwatersrand basin is unique in terms of its mineral wealth. The gold in the Witwatersrand basin is mainly concentrated in the placers and two types of unconformities are associated with the placer formation. This paper attempts to quantitatively describe the origin and depositional process of placers within the context of basin analysis, geohistory and sequences stratigraphic framework. Several tectonic models have been proposed for the evolution of the Witwater~rand basin and it seems as if a cratonic foreland basin accounts for many of the observed features observed the Central Rand Group basin. The tectonic subsidence curve generated for the Witwatersrand Basin clearly implies foreland basin response which was superimposed an older, deep seated extensional basin. These compressive tectonics can be superimposed on extensional basins, where the shift from extensional to compressional tectonics lead to inversion processes. The critical issues about the Witwatersrand basin which were addresed in this review, is the validity of basin wide correlation of placer unconformuties and whether sequence stratigraphy is applicable to fluvial systems of the Witwatersrand sequence. It is believed that the Central Rand Group was deposited as alluvial - fan deltas by fluvially dominated, braidplain systems with minor marine interaction which had a considerable impact on the preservation of economically viable placers. Most important to the exploration geologist is the recognition of stacking patterns of the fluvial strata to determine change in the rate at which accommodation was created. Identifying sequence boundaries and other relevant surfaces important for identifying these stacking patterns of the sequences, depends entirely on the recognition of a hierarchy of stratal units including beds, bedsets, parasequences, parasequence sets and the surfaces bounding sequences. Placers are closely associated with the development of disconformities and therefore become important to recognise in fluvial strata. If these placers are to become economic, the duration of subaerial exposure of the unconformities that allowed the placers to become reworked and concentrated must be determined. In order to preserve the placer, a sudden marine transgression is necessary to allow for minimal shoreline reworking and to cap the placer to prevent it from being dispersed. The placers in the Witwatersrand basin occur in four major gold-bearing placer zones in the Central Rand Group. Accordingly they can be assigned to four supercycles, which are cyclical and therefore predictive. It is the predictive nature of these rocks and the ability of sequence stratigraphy to enhance this aspect, which is a pre-requisite for an effective exploration tool in the search for new ore bodies or their extension in the Witwatersrand basin.
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Brennan, Michael Brendan. "The genesis of ilmenite-rich heavy mineral deposits in the Bothaville/Delmas area, and an economic analysis of titanium, with particular reference to the Dwarsfontein deposit, Delmas district." Thesis, Rhodes University, 1991. http://hdl.handle.net/10962/d1005561.
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A number of ilmenite-rich heavy mineral deposits occur along the northern margin of the intracratonic Karoo basin, and are hosted by the fluvio-deltaic Middle Ecca Group. Coastal reworking of delta front sands within a regressive, microtidal shoreline may be considered as a depositional model for the development of the heavy mineral deposits. An economic analysis of titanium suggests long term positive demand, and sustained high prices for this commodity. An evaluation of the Dwarsfontein ilmenite-rich heavy mineral deposit, using available data, indicates how important it is for deposits of this type to be situated close to an upgrading plant or export harbour.
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Wu, Changhong. "Groundwater Occurrence of Table Mountain area in Cape Town South Africa." Thesis, University of the Western Cape, 2009. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5926_1279233915.
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Groundwater is an important water resource to be used to supplement the water demand for the City of Cape Town for present and future generations. Understanding the groundwater occurrence of the Table Mountain area is very important for future groundwater exploitation and management. Apart from the sea in the west, Table Mountain is mostly surrounded by the unconsolidated sediments including the Kirstenbosch, Newlands, and Oranjezicht areas. These areas are rich in groundwater resources, like springs
some of them were utilized, others not. However, there are few studies that focused on spring resource in this area. No up to date information is available for spring resources research and relative data is lacking from local research institutions. In fact, some of the spring resources in the Table Mountain area had been extracted and been utilized for local community for many years. Data and information newly obtained from this study about such groundwater resources will help future groundwater development and management. There are at least 13 springs in the selected study area. Those springs were investigated for groundwater occurrence, because spring is an important manifestation of the underlying aquifer through which groundwater dynamics can be detected. The main objective of the study was to sketch a clear picture of groundwater occurrence and to obtain an improved understanding of how geomorphology affects groundwater flow, its manifestation and quality. Water resources management is also important because this kind of water resource can be used to help meet the water demand of this local area in the future. There is relationship between the topographical features of the Table Mountain and spring occurrence. The research area delineated is used to interpret the relationship. Hydro-geochemical analysis is carried out to indicate the chemical components of the groundwater and to understand the groundwater type and water quality of this particular area. Based on the completed analysis and interpretation of factors influencing discharge and recharge, some good results were obtained and useful information is made available for first time.
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Tembisa, Papiyana Ayavuya. "Isolation and characterisation of lignocellulose degrading bacteria from Tyume River in the Eastern Cape Province, South Africa." Thesis, University of Fort Hare, 2015. http://hdl.handle.net/10353/d1021293.
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This study focuses on the isolation and characterization of bacteria from lignocellulosic biomass obtained from the sediments of the Tyume River in Alice, Eastern Cape and to determine those bacterial isolates with good potential for modification and decomposition of lignocellulosic biomass for industrial application. Several bacterial isolates were recovered and screened for ability to degrade various lignocellulosic materials. Nine of the isolates were positive for lignocellulolytic activity. Four isolates were cellulase positive and six were xylanase positive. Moreover, one isolate (SB1) was positive for both xylanase and cellulase activities and showed the best hydrolysis zone on solid media. This isolate was then chosen as the best and identified molecularly. The 16S rDNA sequence analysis indicated that SB1 was a Bacillus cereus species. Factors affecting the cellulose and xylanase enzyme production by the organisms were studied. The organisms produced the enzymes maximally at earlier hours of incubation (12-30 hr) and optimally at acidic pH (3-5) and at moderate temperatures (35-45ºC). SB1 appears to hold promise in the decomposition of lignocellulosic wastes.
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Hendricks, Mogammad Yaaseen. "Provenance and depositional environments of early cretaceous sediments in the Bredasdorp Sub-basin, offshore South Africa: an integrated approach." University of the Western Cape, 2020. http://hdl.handle.net/11394/7596.
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>Magister Scientiae - MScSouthern offshore basins of South Africa are well known as potential provinces of hydrocarbon exploration and production. The complex nature of the Bredasdorp sub-basin’s syn-rift architecture (transform fault system) can have adverse effects on reservoir distribution due to periodic local and regional uplift of horsts and grabens. This present investigation focusses on an integrated approach of the 1AT1-V horizon or early Cretaceous sediments in the Bredasdorp sub-basin to identify the depositional environment and provenance of these sediments as well as their role in regionally complex compositional heterogeneities associated with the late stage rifting of Gondwana break-up. An integrated seismic, sedimentological (including petrography and geochemistry) and ichnologic analysis of the 1AT1-V horizon sediments showed an overall lower regressive element complex assemblage set and an upper transgressive element complex assemblage set that occurred as a >120m thick succession. The analysis identified a mixed-energy deltaic succession followed by an estuarine succession. The 1AT1-V interval (late syn-rift) consisted of nine sedimentary facies associations (and associated petrofacies) on a dipslope setting with variations occurring along the strike and the downdip depositional slope areas. Two overall sequences were identified as a lower regressive and upper transgressive sequence (Element complex assemblage sets). The regressive sequence consisted of middle to distal delta front lobe fringes, hyperpycnal event beds (sourced from basement highs), offshore migrating tidal bars (and associated inter-bar regions), distal mouth bars, terminal distributary channels (and associated inter-terminal distributary regions). The distal delta plain to proximal delta front consisted of interdistributary bays, distributary channels, crevasse splay sub-deltas, mouth bars, tidal flats and offshore embayments. In the laterally isolated depocenter, these deposits also consisted of basement high slopes with upliftment of the basement highs leading to proximal/central embayment to regressive shoreface/foreshore environments. These sequences consisted generally of low diversity and intensities (impoverished abundances) of trace fossils. The paleoclimate inference from this sequence indicates a humid climate with intermediate degrees of weathering intensities (possibly fluctuating arid-humid conditions). The transgressive sequence consisted of estuarine sedimentation with the occurrence of tidal sand ridges and compound dune fields, embayment facies and tidal bars. These sequences consisted of relatively higher ichnodiversities and intensities than their relative regressive sequences. The paleoclimate inference during these times consisted of more arid to semi-arid settings with low degrees of weathering in the source terrain. Local tectonic upliftment and subsidence, with exposed basement highs, gave rise to differential process regimes (tidal, wave and fluvial) and hence depositional facies in the diachronous updip/downdip areas (spatial) and within-stratigraphic (temporal) variations. There are several modern analogues that are similar to the 1AT1-V horizon sequence and they are the Mahakam, Ganges-Brahmaputra, Po, Burdekin deltaic and Satpara lake environments Compaction and dissolution diagenetic features as well as transportation were responsible for the major compositional heterogeneities concerning the reservoir quality and distribution. Proximal and distal sources were identified with first cycle and polycyclic sediments being deposited in the northern and southern part of the basin during the late stages of rifting in the Bredasdorp sub-basin. The provenance lithology has been identified as recycled sedimentary rocks (and their meta-equivalents) with an ultimate source terrain that was largely felsic in nature (Cape granite suite). The northern part of the studied section is suggested to have received sediments from the main metasedimentary rocks of the Cape fold belt (including the Table Mountain Group and Bokkeveld Group) whereas the southern sections received more sediments from the basement highs (recycled Malmesbury Group (and Pre-Cape sediments) and Cape granite suite), which is further supported by seismic data. Provenance analysis revealed that the Cape Fold belt (most recent collision) was possibly a provenance terrain but overprinting of several collisions are also acknowledged. The tectonic setting was envisaged to be of a rifted margin during the break-up of Gondwana. This compositional heterogeneity due to facies and provenance-related terrains had major consequences to the reservoir quality and distribution from the northern part to the southern part of the studied section
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Harrison, Bianca. "Palaeoenvironments and position of the Precambrian–Cambrian boundary within the lower Vanrhynsdorp Group of South Africa: sedimentary facies analysis, U-Pb series zircon geochronology and micropalaeontology." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29450.
Full textAbstract:
The Vanrhynsdorp Group is a mainly fluvio-marine siliclastic succession that outcrops in the northwestern part of South Africa. The critical Precambrian-Cambrian boundary falls within the group, however the depositional environments across the boundary, its exact stratigraphic position and nature are unresolved. The group was deposited in the Vanrhynsdorp Basin, which has been shown to be the southernmost extension of the Nama Foreland Basin. Consequently, the Vanrhynsdorp Group has been correlated with the world-famous Nama Group, which features diverse Ediacaran-Cambrian fossils. To date, no body fossils have been discovered in the Vanrhynsdorp Group. Through U-Pb dating of detrital zircons using LA-ICP-MS, radiometric ages for the middle part of the Vanrhynsdorp Group (Besonderheid Formation) were obtained in a preliminary study of this project. The radiometric data, yielding a maximum depositional age of 524 to 528 Ma from the youngest zircon grain population, indicated that the Precambrian-Cambrian boundary is stratigraphically lower in the group than it was thought before. To further constrain the age of the lower Vanrhynsdorp Group, and by extension the position of the Precambrian-Cambrian boundary, several detrital zircon samples were processed for age determination from the succession in this study. In addition, using sedimentary facies analysis, the lateral and vertical facies variation in this lower part of the group were (re)documented in order to refine the palaeoenvironmental setting. The current results suggest a dominantly shallow marine, partly storm-dominated depositional environment for the lowermost units as opposed to the previous interpretations of dominantly alluvial settings. Because of the global importance of the Ediacaran-Cambrian transition for diversification of marine biota in the Cambrian, addressing these palaeoenvironmental inconsistencies is the vital outcome of this study. By integrating our sedimentological and geochronological results, the project presents an improved understanding of the depositional history of the Vanrhynsdorp Group during the critical Ediacaran-Cambrian transition.
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Sekese, Siviwe Pamela. "Geomorphic analysis of river character and behaviour in three semi-arid, mountainous catchments in the Eastern Cape, South Africa." University of Western Cape, 2019. http://hdl.handle.net/11394/7412.
Full textAbstract:
>Magister Scientiae - MScThe analysis of what controls why rivers are the way they are, and how and why they change is crucial in predicting river dynamics and deriving classification systems that can assist management. A variety of factors control the pattern of fluvial styles in a river system across spatial scales. The geomorphic response of a river to an individual control, such as stream power for example, will vary due to a combination of other contributing factors such as geology and climate.
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Vennemann, Torsten Walter. "A geochemical and stable isotope study of some rocks from the Bandelierkop formation, southern marginal zone of the Limpopo Belt, South Africa( vol.1 Text)." Doctoral thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/23476.
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The Bandelierkop Formation of the Southern Marginal Zone (SMZ) of the Limpopo Belt consists of metamorphosed ultramafic, mafic and sedimentary rocks. Metamorphic conditions indicated by the petrography of these different rock groups are consistent with upper amphibolite to granulite facies. The ultramafic and mafic rocks are geochemically akin to peridotitic-pyroxenitic intrusive rocks and high-Mg basalts respectively. Metamorphism of these two rock groups in the SMZ was an essentially closed system process, except for the highly volatile phases such as H₂O and CO₂. The metasediments appear to represent a sequence of high (Mg+Fe)-greywackes and/or deep-water shales with minor amounts of iron formation material. The unusually mafic character of the metasediments can be ascribed to a high ultramafic + mafic source component to the original sediment. Some modification of the major and trace element compositions of the pelitic rocks has been caused by the removal of partial melts and the metamorphism of the pelitic rocks is not therefore considered to have occurred under closed system conditions. Variable extraction of partial melts is implied by the chemical variations shown by the pelitic rocks and is also suggested by the presence of large pegmatitic felsic bodies which are commonly found close to the pelitic rocks. Detailed petrographic study of the Bandelierkop Formation rocks suggests an increase in metamorphic grade, and/or a decrease in water activity, from south to north within the Southern Marginal Zone. Peak metamorphic conditions of 730°C + 65°C at pressures of 6.1 ± 1.5 kbars may be deduced from a careful application of several cation thermometers and barometers on selected mineral analyses. A rigorous application of garnet-biotite thermometry to the pelitic rocks indicates that the transition from orthoamphibole gneisses in the south to orthopyroxene-bearing rocks in the north of the SMZ terrane, is a function of changing biotite composition and/or decreasing water activities rather than an increase in metamorphic temperatures. In contrast to the major and trace element data, the stable isotope data for the ultramafic and mafic rocks in the SMZ indicate open system behaviour for some of these rocks, but closed system behaviour for the pelites. Extraction of SO to 70% partial melts from the pelitic rocks, should not, however, have affected the δ¹⁸O value of the restite. Petrological and stable isotope data in the SMZ rocks are consistent with retrogression in all these rocks and open system behaviour for oxygen in some ultramafic and mafic rocks, being caused by the crystallization and accompanying fluid release of melts produced during prograde metamorphism of the pelitic rocks. Small scale (-5 to 30m's) heterogeneity is implied by both oxygen and carbon stable isotope compositions of closely spaced rock samples, even for those collected from within large "shear zones", suggesting small fluid/rock ratios for most of the samples in the high-grade terrane or heterogeneous stable isotopic compositions of the fluids. Furthermore, a similarity in mineral-mineral stable isotope fractionation factors is observed for all the pelitic rocks, including the orthoamphibole gneisses found immediately south of the orthopyroxene isograd. These features preclude the presence of pervasive fluid infiltration after peak metamorphism. Two implications are, that granulite facies metamorphism in the SMZ terrane was not caused by an influx of mantle derived CO₂-rich fluid and, that the orthoamphibole gneisses are not retrogressed equivalents of the granulites found to the north of the orthopyroxene isograd. It is suggested that this isograd represents a change in the water activities of the rocks during metamorphism. Apparent disequilibria in mineral - mineral stable isotope fractionations observed amongst different minerals within any one pelitic rock, may be explained by a combination of the crystallization of residual melt within these rocks and oxygen diffusion amongst minerals which have not reached their oxygen-closure. The concordant quartz-plagioclase, quartz-biotite and plagioclase-biotite oxygen isotope equilibration temperatures are taken to represent minimum crystallization temperatures for the melts (-560°C), while successively higher quartz-orthopyroxene, quartz-amphibole and quartz-garnet oxygen isotope equilibration temperatures are a function of increasing closure temperatures for the orthopyroxene, amphibole and garnet respectively. The minimum estimate to peak metamorphic temperatures is given by the quartz-garnet oxygen isotope temperature averaging 736 + 52°C. If oxygen diffusion experiments performed in hydrothermal systems are appropriate for the SMZ rocks, then cooling rates for the SMZ terrane could have been as low as 12 to 25°C/My over a temperature range of 480 to 600°C. Stable isotope modeling of hypothetical fluids that may have been in equilibrium with the high-grade rocks, suggests that a mixture of CO₂ and H₂O, with CO₂/H₂O mole ratios > 0.1 can precipitate both quartz and carbonate of stable isotope composition similar to those determined for quartz and carbonate from the mineralized Archaean lode gold deposits of the Murchison and Pietersburg greenstone belts. A model involving granulite facies metamorphism, partial melt extraction and subsequent release of fluids, Au, K and S upon crystallization of such melts, appears to be viable for gold mineralization occuring in the adjacent lower grade greenstone belts and in the high-grade terrane of the Southern Marginal Zone.
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Shackford, Julia Keegan. "Continuous Late Pleistocene Paleoclimate Record from the Southwest African Margin: A Multi-Proxy Approach." unrestricted, 2005. http://etd.gsu.edu/theses/available/etd-04212005-174202/.
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Thesis (M.S.)--Georgia State University, 2005.Title from title screen. Beth A. Christensen, committee chair; W. Crawford Elliott, Eirik J. Krogstad, Deborah Freile, committee members. Description based on contents viewed Dec. 22, 2006. Includes bibliographical references (p. 107-112).
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Duncan, C. E. "Holocene environmental change and the vegetation community dynamics of the Kynsna forest : pollen and charcoal analysis of sediments from Groenvlei, Southern Cape, South Africa." Master's thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/4847.
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Includes bibliographical references.To establish an understanding of the long-term community dynamics of the Knysan forests, and gain a better understanding of the impacts of colonial exploitation of the forests agains a background of environmental change, sediments were extracted from the lake shore of Groenvlei, an endorheic coastal vlei in the Wilderness Lake system on the southern Cape coast, some 10 km from the present-day forest core. These sediments were described, dated by radiocarbon means and subsampled for the analysis of fossil pollen and charcoal particles, environmental proxies used respectively to infer a vegetation and fire history for the region.
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Spaggiari, Renato Igino. "Sedimentology of plio-pleistocene gravel barrier deposits in the palaeo-Orange River mouth, Namibia : depositional history and diamond mineralisation." Thesis, Rhodes University, 2011. http://hdl.handle.net/10962/d1004636.
Full textAbstract:
The largest known marine diamond placer, the Namibian mega-placer, lies along the Atlantic coast of south-western Africa from the Orange River mouth 1,000 km northwards to the Namibian-Angolan border. The most economically viable portion of the Namibian mega-placer (>75 million carats recovered at >95% gem quality) comprises onshore and offshore marine deposits that are developed within ∼100km of the Orange River outfall. For much of the Cainozoic, this long-lived fluvial system has been the main conduit transporting diamonds from kimberlitic and secondary sources in the cratonic hinterland of southern Africa to the Atlantic shelf that has been neutrally buoyant over this period. Highly energetic marine processes, driven in part, by southerly winds with an attendant northward-directed longshore drift, have generated terminal placers that are preserved both onshore and offshore. This study, through detailed field sedimentological and diamond analyses, investigates the development and mineralisation of gravel barrier deposits within the ancestral Orange River mouth area during a major ∼30 m regional transgression ('30 m Package') in the Late Pliocene. At that time, diamond supply from this fluvial conduit was minimal, yet the corresponding onshore marine deposits to the north of the Orange River mouth were significantly diamond enriched, enabling large-scale alluvial diamond mining to take place for over 75 years. Of the entire coastline of south-western Africa, the most complete accumulation of the '30 m Package' is preserved within the palaeo-Orange River mouth as barrier spit and barrier beach deposits. Arranged vertically and laterally in a 16m thick succession, these are deposits of: (1) intertidal beach, (2) lagoon and washover, (3) tidal inlet and spit recurve and (4) storm-dominated subtidal settings. These were parts of larger barrier features, the bulk of which are preserved as highstand deposits that are diamond-bearing with varying, but generally low grades (<13 stones (diamonds) per hundred tons, spht). Intertidal beach and spit recurve deposits have higher economic grades (12-13 spht) due to the energetic sieving and mobile trapping mechanisms associated with their emplacement. In contrast, the less reworked and more sandy subtidal, tidal inlet and washover deposits have un-economic grades (<2 spht). Despite these low grades, the barrier deposits have the largest average stone (diamond) size (1-2 carats/stone, cts/stn) of the entire Namibian mega-placer, given their proximity to the ancestral Orange River outfall. This study demonstrates that barrier shoreline evolution at the fluvial/marine interface was controlled by: (1) a strong and coarse fluvial sediment supply that sustained shoreline growth on a highly energetic coast, (2) accommodation space facilitating sediment preservation and (3) short-duration, high-frequency sea-level cycles superimposed on the∼30 m regional transgression, promoting hierarchal stacking of progradational deposits. During these sea-level fluctuations, diamonds were 'farmed' from older, shelf sequences in the offshore and driven landward to accumulate in '30 m Package' highstand barrier deposits. In spite of the large supply of diamonds, their retention in these deposits was poor due to an incompetent footwall of ancestral Orange River mouth sediment and the inherent cobble-boulder size of the barrier gravels. Thus the principal process controlling diamond entrapment in these barrier deposits was kinetic sieving in a coarse-grained framework. Consequently, at the marine/fluvial interface and down-drift for ∼5 km, larger diamonds (1-2 cts/stn) were retained in low-grade (<2 spht), coarse-gravel barrier shorelines. Smaller diamonds (mostly < I cts/stn) were rejected into the northward-driven littoral sediments and further size-sorted along ∼95 km of Namibian coast to accumulate in finer, high-grade beach placers (> 100 spht) where bedrock footwall promoted such high concentrations. The gravel-dominated palaeo-Orange River mouth is considered to be the ' heart' of the Namibian mega-placer, controlling sediment and diamond supply to the littoral zone further north. Although coarse gravel is retained at the river mouth, the incompetence of this highly energetic setting to trap diamonds renders it sub-economic. This ineffectiveness at the fluvial/marine interface is thus fundamental in enriching the coastal tract farther down-drift and developing highly economic coastal placers along the Atlantic coast of south-western Africa.KMBT_363
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Adriaans, Luke. "Geology, geochemistry and Sr-Nd isotope analysis of the Vredenburg Batholith and Cape Columbine Granites Paternoster/Vredenburg, South Africa: Implications on their petrogenesis, tectonic setting, and sources." University of the Western Cape, 2018. http://hdl.handle.net/11394/6527.
Full textAbstract:
>Magister Scientiae - MScThe late− to post−collisional Cape Granite Suite (CGS) located in the southwest of South Africa is comprised of S−, I−, and A−type granites, mafic intrusives, and volcanic flows. The CGS is interpreted to have formed during the closing of the Adamastor Ocean during the Late−Proterozoic to Early−Cambrian. Recently, the S−type granites have received much attention concerning their petrogenesis and sources. However, the I− and A−type granites remain poorly understood and little studied. Therefore, with new geochemical and isotopic data the petrogenesis, sources, and tectonic settings of I− (Vredenburg Batholith) and A−type (Cape Columbine) granites of the CGS form the focus for this study. The major and trace element data presented in this thesis show that the granites from the Vredenburg Batholith are weakly peraluminous to metaluminous, ferroan, and alkali−calcic. Associated with the granites are metaluminous, magnesian, and calc−alkalic igneous enclaves. Formerly, the granites have been interpreted to have formed by fractionation. However, with new geochemical analyses and reassessment of such models, it can be shown that such processes are incompatible with accounting for the chemical variation displayed by the granites and their enclaves. Moreover, the I−type granites and enclaves exhibit positive linear trends between whole−rock major and trace elements vs. maficity (Fe + Mg), which can be explained by co−entrainment of peritectic and accessory phases. The lithogeochemical characteristics of the enclaves and host granite reflect melting of a heterogeneous source. Moreover, the granite and enclave's εNd(t) values reflect melting of Paleoproterozoic-aged crustal sources. Finally, with tectonomagmatic discrimination diagrams, it can be shown that the tectonic setting of the granites indicates a transition from a collisional to extensional regime which corroborates the inferences of previous studies. The Cape Columbine Granites lithogeochemical characteristics are ferroan, calc−alkalic and weakly peraluminous. They show typical A−type granite characteristics in having high silica content, high Na + K values, REE enrichment as compared to S− and I−type granites and strong negative Eu anomalies. For this thesis, it can be shown that anatexis of quartzofeldspathic protolith in an extensional regime produced the chemical variation of the Cape Columbine Granite. Moreover, their isotope ratios are typically radiogenic, indicative of a crustal origin. With this new geochemical data evidence is provided against and in support of previous inferences made about the petrogenesis of the I− and A−type granites of the CGS. This also betters our understanding of the magmatic processes involved in the construction of the CGS over time.
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Bowen, Michael Peter. "The petrogenesis of the volcanic rocks of the Witwatersrand triad in the Klerksdorp area, Transvaal." Thesis, Rhodes University, 1985. http://hdl.handle.net/10962/d1001569.
Full textAbstract:
Several hundred chemical analyses of early Proterozoic lavas of the Witwatersrand triad (incorporating the Dominion Group, Witwatersrand Supergroup and Ventersdorp Supergroup) in the Klerksdorp area, have revealed the presence of various distinct magma types. These essentially correspond to formally defined lithostratigraphic units, but several inconsistencies have necessitated the use of informal nomenclature. The lavas have been regionally metamorphosed to low-grade, greenschist facies assemblages. Original igneous textures are preserved, despite a metamorphic overprint. Metamorphism has resulted in a certain degree of random chemical remobilization. Ba, Sr, Rb, K₂0, Na₂0 and CaO have been highly mobile, and their usefulness in petrogenetic modelling is extremely limited. In contrast, Zr, Nb, Y, LREE's, Cr, Ni, Ti0₂ P₂0₅ and Al₂0₃ have remained immobile. Ti/Zr and Ti/P ratios together constitute efficient discriminating variables for characterizing the different magma types. Lava compositions range from primitive Mg-rich tholeiites to rhyolites, the bulk being tholeiitic andesites. Al₂0₃ contents do not exceed 15%, a feature which reflects the tholeiitic, as opposed to calcalkaline, character of these lavas. Two magma-types are present within the Dominion Group, which is a typical example of bimodal volcanism. The Dominion basic lavas are overlain by the Dominion acid porphyries, with a limited amount of interfingering. The basic lava suite is highly fractionated, with compositions ranging from Mg-, Cr- and Ni-rich tholeiites (close to primary mantle melts) to evolved tholeiitic andesites. The most primitive liquids evolved by 45% fractional crystallization of hornblende, followed by a further 70% crystallization of an orthopyroxene-plagioclase assemblage containing up to 3% sulphides. The Dominion porphyries are rhyolitic, display very limited compositional variation, and probably represent a crustal melt related to the same magmatic event which produced the basic lavas. The only lavas from the Witwatersrand Supergroup present in the Klerksdorp area are those of the Crown Formation (Jeppestown amygdaloid). These are tholeiitic dacites which display extremely limited compositional variation, and are unrelated to any of the other magmas of the Witwatersrand triad. The Ventersdorp Supergroup comprises 4 magma-types: The Kliprivierberg Group lavas at the base are subdivisible into 3 sub-types on the basis of Zr contents. (Zr>11Oppm) are the most evolved. They are tholeiitic andesites which display fairly limited compositional variation. It is likely that more evolved compositions are present in other areas where the porphyritic lavas which characterize this unit are better developed. The overlying Orkney lavas are characterized by 110ppm>Zr>90ppm. They are tholeiitic andesites of similar composition to the Alberton lavas, but have lower incompatible element levels, higher siderophile element levels, and are of extremely uniform composition. The uppermost Loraine/Edenville lavas range from magnesian tholeiites to tholeiitic andesites. They are distinguished by Zr< 90ppm, and contain the most primitive magmas af the Witwatersrand triad, with up to 17,5% MgO, 2600ppm Cr, 600ppm Ni and M-values up to 77. The most primitive liquids evolved by 38% fractional crystallization of orthopyroxene ∓ chromite, followed by 35% fractional crystallization of an extract containing clinopyroxene and plagioclase. The absence of olivine precipitation is a result of the inherently high Si0₂ content of the magma. The Loraine/Edenville, Orkney and Alberton lavas do not lie on a common liquid line of descent, but are probably consanguinous. The Platberg Group overlies the Kliprivierberg Group, and has a coarse-clastic sedimentary unit, the Kameeldoorns Formation, at the base. Three petrographically distinct porphyritic lava sequences overlie the Kameeldoorns Formation, namely the informal "Goedgenoeg formation", the Makwassie quartz-feldspar porphyries and the Rietgat Formation. Despite petrographic differences, the Goedgenoeg and Rietgat lavas are chemically indistinguishable and thus form a single magma-type. The Makwassie porphyries are dacitic in composition with a high proportion of feldspar and quartz phenocrysts. Rational variation trends are attributed to a nett loss of Si0₂ during secondary alteration. The porphyries are probably of crustal origin. The Goedgenoeg/Rietgat lavas display unusual chemistry and a broad, irrational compositional spectrum. They contain very high incompatible element levels, high nonnative quartz, as well as high MgO, M-values, Cr and Ni relative to the other tholeiitic andesites of the Witwatersrand triad. It is tentatively suggested that they are hybrid magmas containing both crust and mantle components, the former possibly represented by the Makwassie porphyries. Field evidence suggests that Platberg volcanism commenced directly after Klipriviersberg volcanism ceased, and was accompanied by a period of enhanced tectonic activity. The Platberg lavas thus probably reflect a crustal melting cycle associated with the Klipriviersberg magmatic event. The Allanridge lavas are the youngest rocks of the Witwatersrand triad. They are separated from the Platberg Group by a unit of flat-lying sediments, the Bothaville Formation, which was deposited after an extended period of peneplanation. The Allanridge lavas form a separate magma-type. They are tholeiitic andesites of similar composition to the Alberton lavas, but have higher incompatible element levels and are not consanguinous. The compositional similarities amongst the basic magma-types of the Witwatersrand triad suggests that all were generated in an hydrous mantle. Interelement ratio differences between the various magma-types nevertheless support the concept that the mantle was chemically heterogeneous during the early Proterozoic.
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Sonwa, Cyrille Stephane Tsakou. "Analysis of the structural geology of the high-grade metamorphic rocks in part of the Kakamas terrane of an area adjacent to the Neusspruit shear zone South of the orange river, Northern Cape, South Africa." University of the Western Cape, 2021. http://hdl.handle.net/11394/8257.
Full textAbstract:
>Magister Scientiae - MScThe Proterozoic Namaqua-Natal Province comprises highly deformed rocks of medium to high grade metamorphism and is bordering the Archean Kaapvaal Craton to the west, south and east in South Africa. The sector to the west of the Craton, namely the Namaqua Sector, is structurally complex and subdivided from west to east into the Bushmanland Subprovince, the Kakamas and Areachap terranes of the Gordonia Subprovince and the Kheis Subprovince. The prominent Neusberg Mountain Range, with exposures to the north and south of the Orange River in the Kakamas Terrane constitutes evidence of crustal shortening as a result of continental collision of the Namaqua Sector block with the Kaapvaal Craton during the Namaquan Orogeny. The Mesoproterozoic Korannaland Group in the Kakamas Terrane is affected by faulting, folding and shearing.
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Shaddock, Bridget Florence. "Development of a sediment quality triad approach to evaluate sediments in marine and freshwater environments of South Africa." Thesis, 2014. http://hdl.handle.net/10210/11412.
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Colarossi, Debra. "Geology and geochronology of the Nyl River floodplain sediments, Limpopo province, South Africa." Thesis, 2013. http://hdl.handle.net/10539/12951.
Full textAbstract:
A Dissertation submitted to the Faculty of Science, University of the Witwatersrand,
Johannesburg, in fulfilment of the requirements for the Degree of Master of Science
in Geology.
Johannesburg 2013The Nyl River floodplain, located in the Limpopo Province, is one of the few active sedimentary basins that exist within the South African interior, providing a unique opportunity to study the effect of climate change on fluvial systems. Progradation of tributary fans into the Nyl/Mogalakwena River has raised the surface by 30 m and forced the course of the river westwards towards the Waterberg. Periods of progradation deposited thick sequences of coarse-grained sediments with sand- to gravel-sized mean grain sizes and coarsely-skewed populations in the distal reaches of the tributary fans. These periods were interspersed with periods of relative non-deposition, when active sedimentation on the fan ceased and shallow lakes (or vleis) developed in the trunk river, resulting in deposition of fine-grained, organic-rich, floodplain sediment layers with silt-sized mean grain sizes and finely-skewed distributions in the extreme outer reaches of the tributary fan. The alternating progradational sequences and non-deposition events produced interlayered floodplain and fan deposits in the furthest reaches of the tributary fans along the banks of the Nyl/Mogalakwena River. Incised river cuts within the Rooisloot tributary fan were dated using OSL and 14C techniques. For OSL samples, the SAR protocol was used to measure the equivalent dose and the burial dose was determined using the CAM and MAM. Emission counting methods, including TSAC, GM-beta counting and HRGS were used to determine the dose-rate. The OSL ages ranged from 99 years to 3884 years, constraining the sampled deposits within the late Holocene. Although the 14C ages agreed with this range, carbon contamination of the samples resulted in inverted and overestimated ages. Based on stratigraphic relationships the non-deposition events have been dated at approximately 750–800 years ago, 600 years ago, 475 years BP and 100–150 years ago and two major periods of aggradation at ~ 800–1000 years ago and ~ 500–700 years ago. The rate of aggradation (0.29 cm/year) calculated implies that the entire 30 m deposit could have been deposited in 9 000 years. However, an independent study by McCarthy et al. (2011) proved that tributary sedimentation began prior to 220 ka. Therefore, in order to deposit 30 m of sediment over 220 ka, either the mid – late Quaternary sedimentation rate was lower than the recent past (Late Holocene) or the system periodically undergoes extensive erosion in order to flush the accumulated sediment from the tributary fan system.
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Steininger, Christine Marrie. "The dietary behaviour of early pleistocene bovids from Cooper's Cave and Swartkrans, South Africa." Thesis, 2012. http://hdl.handle.net/10539/11390.
Full textAbstract:
Ph.D., Faculty of Science, University of the Witwatersrand, 2011There is ongoing speculation about how an increasingly arid environment contributed to the extinction of Paranthropus robustus, given that a mosaic landscape with a major part of the area consisting of predominantly open grassland environment accompanied by an escalating cooler drier climate remains the persistent palaeoecological reconstruction for this species. It has been suggested that P. robustus, a dietary specialist, was not able to adapt to an increasingly xeric habitat. This notion has been challenged by recent multi-disciplinary research on P. robustus remains, including stable light isotope and dental microwear analyses, which portray a more complex diet. Paranthropus robustus is present in a number of key fossil assemblages spanning the period ca. 1.8 to 1.0 Ma. Analysis of the stable carbon isotope composition of bioapatites and dental microwear texture analysis of different bovid taxa, associated with P. robustus remains from five discrete deposits, were used to reconstruct dietary behaviour and by inference availability of local resources. The overall pattern emerging from the bovid data indicates a more mixed and varied diet than previously thought, suggesting a heterogeneous environment, and hence a less static ecological profile for Paranthropus. The significant occurrence of mixed diets and relatively few obligate C4 grazers suggest that although C4 grasses were available in a mosaic environment, a C4-dominated ecosystem was not present. Swartkrans Member 2 (ca. 1.6 Ma) contains substantially more C3 feeders than other P. robustus deposits, signifying a vegetation community structure that was more C3-dominated than the other deposits. There is an apparent indication of shifting vegetation structure between P. robustus deposits. Thus, despite its derived craniodental morphology, P. robustus seems to have thrived through a range of climatic and ecological shifts by selecting from a variety of available foods present on the landscape.
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Obbes, August Murray. "The structure, stratigraphy and sedimentology of the Black Reef-Malmani-Rooihoogte succession of the Transvaal supergroup south-west of Pretoria." Thesis, 2014. http://hdl.handle.net/10210/12713.
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"Sedimentology of the Middelvlei Reef on Doornfontein Gold Mine." Thesis, 2015. http://hdl.handle.net/10210/14353.
Full textAbstract:
M.Sc.Doornfontein Gold Mine is the westernmost member of a group of mines in the West Wits Line, extending from Westonaria to Carletonville. A study of the sedimentology and gold distribution of the Middelvlei Reef was carried out with the aim to acquire an understanding of the processes responsible for the economic concentration of gold ...
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Jolly, Malcolm Kenneth. "The sedimentology and economic potential of the auriferous Middelvlei Reef on Driefontein Consolidated Limited." Thesis, 2015. http://hdl.handle.net/10210/14393.
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Sudan, Pascal. "Sedimentology, stratigraphy and geological history of part of the northern KwaZulu-Natal coastal dune cordon, South Africa." Thesis, 1999. http://hdl.handle.net/10413/4631.
Full textAbstract:
The northern KwaZulu-Natal coast is backed by a continuous aeolian dune cordon that rises
in places, to a height of more than 100 metres and a width of 2 kilometres. This MSc thesis
documents the geomorphology of the area, as well as the mineralogical, geochemical and
textural variation of nine boreholes within a small part of the coastal dune cordon between Lake
Nhlabane and Cape St.-Lucia. The results provide useful constraints on the identification of
individual beach and aeolian dune systems, their age relationships and spatial distribution.
Aeolian dunes within the coastal dune cordon were studied using aerial photographs and
grouped into five dune classes that reflect their relative age. These comprise 1) a system of
highly weathered dunes inland of the present coastal dune cordon, that are thought to represent
older dune cordons; 2) a system of weathered and reworked dunes located on the most inland
portion of the coastal dune cordon; 3) a less altered, large field of linear parallel dunes located in
the northern part of the study area; 4) a system of large scale parabolic dunes; and 5) a system of
coastal, relatively unweathered small parabolic dunes.
Mineralogy, geochemistry, texture and SEM analysis of borehole samples revealed a
complex internal structure within the present coastal dune cordon. In the most inland part of the
dune cordon, a basal light grey unit (Unit K) presents similar characteristics to the Kosi Bay
Formation. This is overlain by Unit A, comprising beach and dune systems, characterised by a
very high heavy mineral content. Unit A also forms the basal unit of the central and coastal
portions of the dune cordon. Unit B contains a mixture of reworked sediments from Unit A and
younger sediments. Aeolian Units D and E form the upper part of the dune cordon. Units D and
E were derived from beach - foredune systems and contain a high carbonate bioclast content.
All units are interpreted to be derived from immature sediment from the Tugela River and
mature sediment from the continental shelf. In the southern part of the study area, an additional
unit (Unit C) with unique characteristics has been interpreted as an aeolian deposit reworked
from local fluvial sediments. The units identified from their sedimentological characteristics can
be directly correlated to the regional dune classes identified from the geomorphology.
Luminescence dating of two calcareous dunes was undertaken, revealing that only the
sediment of the small coastal parabolic dunes (Dune Class 5, Unit E2) is of Holocene age. The
deposition of the large field of linear dunes (Dune Class 3, Unit D2) took place between 15 000
and 11 000 BP, during the marine transgression following the last glaciation. Luminescence
dating also indicated that both dunes were subject to at least one major reworking event.
A study on the weathering characteristics of the dunes can be used to attribute a relative age
to the nine sedimentological units. With the help of sea level curves and the two luminescence
dates, the nine units were attributed an approximate absolute age and regrouped into four
sediment packages thought to broadly represent four interglacial periods. The three younger
packages are attributed to the penultimate interglacial (lower part of Unit A), last interglacial
(upper part of Unit A, Units B and C) and "Holocene" interglacial (Units D and E). Hence the
northern KwaZulu-Natal coastal dune cordon under study represents a complex stacking of
three generations of coastal dune cordons, and appears to be constituted of sediments with age
ranging from at least two hundred thousand years ago to present.
The oldest sediment package (Unit K), interpreted as the Kosi Bay Formation, and the older
dune cordons (Dune Class I) must be older than 200 000 years, which is older than considered
by previous studies. The "Holocene" dune cordon (Units D and E) is interpreted as the Sibayi
Formation.Thesis (M.Sc.)-University of Natal, Durban, 1999.
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Roelofse, Tiani. "Mineralogy and geochemistry of clay sediments in pans of the Northern Cape Province, South Africa." Thesis, 2010. http://hdl.handle.net/10413/5355.
Full textAbstract:
This thesis reports the results of a mineralogical and geochemical study of pans situated in the
Northern Cape Province with special emphasis on the clay minerals. From east to west the
depth and size of the pans increase and associated with this increased maturity the abundance
of salt (halite and thenardite) and the quantity of green sediment are also enhanced.
Chemically the sediments are dominated by SiO2 that also dilutes Fe2O3, K2O, Na2O, Al2O3
and MgO (when associated with dolomite) concentrations. Authigenic calcite, dolomite,
analcime and loughlinite (Na-sepiolite) occur in some of the pans to the west and FTIR
spectrometry indicates that all the pans host glauconite and/or celadonite. However, smectite,
illite/smectite interstratification, kaolinite and/or chlorite and loughlinite only occur in some
pans. The glauconite and/or celadonite does not occur as discrete mineral grains, but forms
part of the fine-grained matrix common to all of the pans and no evidence of any precursor
minerals were observed. The pan environment appears to present a closed, saline setting that
is conducive for the direct precipitation of a mica with a chemical composition between that
of glauconite and celadonite. The influence of the water-table on the formation of the
glauconite and/or celadonite appears to be significant, as the highest abundance of salt is
invariably associated with the position in the profile where the sediment appears to reach its
most intense green colour. In the case of Koi Pan, the celadonite component of the solid
solution seems to increase as the green colour intensifies. Loughlinite in Koi Pan and Brak
Pan sediments also appear to be authigenic and it is suggested that it forms after precipitation
of low Mg calcite that leads to Mg enrichment of the system and consequent sepiolite
formation associated with minor dolomite. Thermoluminescence ages obtained from the Koi
Pan sediment range between 37ka and 48ka before present at a depth of ~120cm below the
surface, while for Brak Pan, at roughly the same depth, an age of between 110ka and older
than 150ka before present was obtained. This may suggest different sedimentation rates in the
pans or much younger ages and thus faster formation of glauconite and/or celadonite in Koi
Pan since it is suggested that the mineral is authigenic.Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2010.
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Burri, Nicole M. "Depositional slope surface of the western margin of the Nylsvlei, South Africa : active piedmont aggradation and sedimentation processes." Thesis, 2014.
Abstract:
The Nyl River and its floodplain are situated on the eastern foothills of the Waterberg mountain range in the Limpopo Province of South Africa. Tributaries flowing out of the Waterberg range display unusual downstream changes, as they approach and converge with the Nylsvlei (or Nyl floodplain). Tributary channels decrease in size downstream until, eventually, they disappear altogether forming unchannellized floodouts. On one such floodout, on the farm Driefontein, an actively aggrading piedmont has formed adjacent to the famous Wonderkrater peat mound, known for its pollen record dating back ~45,000 years. Sediments from the aggrading piedmont interlace with Wonderkrater’s peat layers, suggesting that as the piedmont aggrades so too does the peat mound. This setting presents a unique opportunity to study active aggradational processes, and their products, on hillslope deposits and floodout environments. This study aims to describe the geomorphology and nature of depositional processes along the length of the piedmont adjacent to the Wonderkrater peat mound. Cross-sections, drainage channels and vegetation indices based on topographic maps, orthophotographs and hyperspectral images, were created using ArcGIS in order to describe and determine the surface morphology and hydrology of the Driefontein piedmont in detail. Surface soil samples were collected in order to determine particle size distribution, which were in turn compared to vegetation indices and changes in slope elevation. Further grain samples were collected from depth for age dating using Optically Stimulated Luminescence (OSL), as well as to determine grain size distribution in relation to surface sediments and other fluvial environments. Hyperspectral indices were found to correlate to surface grain size distribution, demonstrating that the presence of vegetation acts as a retaining mechanism for particles along hillslopes where incline should be too steep to support fine-grained sedimentary material. Surface sediments were found to demonstrate the characteristics of an alluvial floodout system, affected greatly by the presence of vegetation and slope inclination. Sub-surface samples were characteristic of a colluvial setting, suggesting that pediment retreat and basin fill, coupled with evidential climatic changes, were dominant controls on the pediment’s morphological and aggradational mechanisms. OSL age results estimated the sediments to be between 37.33 and 58.66 ka old. As a result of its unique sedimentary characteristics, a new type of ‘slow creep fan’ class was established in order to describe the characteristics of the Driefontein piedmont.
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Evans, Mary Yvonne. "The geology, sedimentology, geochronology and palaeo-environmental reconstruction of the Heelbo hillslope deposit, Free State Province, South Africa." Thesis, 2016. http://hdl.handle.net/10539/19373.
Full textAbstract:
Thesis submitted in fulfillment of the requirements for the
Degree of Doctor of Philosophy
University of the Witwatersrand
South Africa
2015A multidisciplinary sedimentological, stratigraphic, mineralogical and geochronological analysis of a small, fossil-bearing, Holocene hillslope deposit, flanking a mesa, has enabled a reconstruction of the palaeo-environmental history of the region. The hillslope deposit, located on the farm Heelbo in the eastern Free State Povince, South Africa, overlies Jurassic mudrock and sandstone of the Elliot Formation, Karoo Supergroup. The deposit is located on a steep (~10°) slope and covers an area of ~7 km2 in two separate sections. It extends ~475 m downslope and reaches a maximum thickness of at least 6-8 m towards the base. Mineralogy indicates the deposit is sourced from the mesa but its fine grain size and location on a steep slope position Heelbo outside the scope of traditionally described alluvial fans or colluvial deposits. The hillslope deposit is described as an alluvial slope based on the morphology of the deposit and the grain size distribution against the slope gradient. The deposit comprises fine-sand to silt- grain size, but is found on a steep (~10°) slope. The source of the sediment is shown to be the sediment of the mesa, rather than input from an aeolian source. The grains are described as sub-angular and poorly sorted which also suggests a local provenance for the sediment. Microscopic and XRF analysis confirm the derivation of the sediment from the Elliot Formation, with the lithic fragments derived from subarkoses to arkoses of the underlying bedrock of the Upper Elliot Formation (UEF) in the Karoo Supergroup. Secondary calcite was visible in only two of the thin sections, thus it is likely due to a diagenetic overprint that is constrained by depth from the surface or time and not to specific layers. The deposit is cut by several mature and continuous gully networks with V-shaped profiles in the proximal slope, and combined V- and U-shaped profiles in the medial and distal sections. Gully formation is linked to both the sodium adsorption ratio (SARs), and high soil clay content, which facilitates swelling and shrinking. The Heelbo deposit comprises two palaeosols (BT1 and BT2) and four sediment (B1, B2, RB and TS) horizons. Through luminescence dating, the ages were found to be approximately 6390 ± 740 years BP for the oldest Brown (B1) horizon and 250 ± 170 years BP for the Red Brown (RB) horizon. The radiocarbon ages of the sediment were inconclusive, but the 14C ages of the fossil bones were in agreement with the luminescence ages. The multiple palaeosol horizons identified suggest two cycles of deposition, pedogenesis and erosion of the alluvial succession. The palaeosols and the presence of calcareous nodules and rhizocretions, and smectite and mixed-layer clay minerals, together with the total absence of illite and kaolinite, suggest protracted, dry periods with intermittent short periods of high rainfall. This is a similar climate regime to what the region experiences currently. Main findings: The Heelbo alluvial slope comprises locally derived sediment, rather than an aeolian source. Heelbo suggests that the hillslope deposits classification system needs to be re-evaluated and opens opportunities for wider study of Pleistocene-Holocene hillslope deposits in central / northern South Africa. This study also contributes to climate change debates in the Holocene.
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Pentz, Tarryn Susan. "Chemical characterisation of sediments and its correlation with the bioavailability of selected heavy metals." Thesis, 2012. http://hdl.handle.net/10210/6327.
Full textAbstract:
M.Sc.The study looks into the sediment-bound metals (Fe, Mn, Cu, Cr, Cd, Co, Pb, Ni, Zn and Hg) of the Leeu/Taaibospruit catchment, which is impacted by agricultural, industrial and urban development. A number of chemical procedures, including total metal determination, the Tessier-sequential extraction scheme, the BCR Protocol, evaluation of the % TOC and determination of AVS to SEM ratios were applied to sediment samples collected from eight sites along the two rivers in the study area. Samples were collected during both high flow (summer) and low flow (winter) conditions. Following the chemical characterisation, bioaccumulation testing was conducted by exposing chironomid larvae to the sediment samples collected in from the study sites and determining their metal uptake relative to control specimens in uncontaminated sediments. These bioaccumulation results were then considered in conjunction with the chemical parameters in an attempt to identify any trends and correlations. Significant spatial and temporal differences were found in the metal concentrations from the study area. The total extraction results indicated that abundant amounts of Cr and Fe are present throughout the system. This was expected based on the make-up of the underlying geology. In addition, one of the sites, which is in close proximity to the town of Sasolburg, was identified as a potentially contaminated site. This site had significantly higher concentrations of Zn, Cu, Pb and, most notably, Hg when compared to the other sites. The elevated metal concentrations are most evident in samples collected under low flow conditions, but are also seen in the high flow Hg concentrations. Sequential extractions showed that Fe and Cr are concentrated in the residual phases of the sediment. Copper is largely present in the oxidisable fraction under low flow conditions, but also has considerable residual and reducible chemical forms. Manganese and Zn are distributed among all the different chemical phases and are therefore likely to be readily available for uptake by benthic organisms. The TOC was found to be highest during low flow conditions and at those sites with observable amounts of organic debris from the surrounding reeds and other vegetation. The AVS/SEM ratios were used to predict that due to the formation of insoluble metal sulphides, Cd, Cu, Hg, Ni, Pb and Zn are unlikely to be bioavailable at certain sites, i.e. the contaminated site 1 and at site 5, which only has agricultural impacts. In general, the bioaccumulation of Fe, Co, Ni, Cr and Mn was higher in the test larvae than the control larvae. Bioaccumulation of Cu, Pb, Zn and Hg levels were only higher than the control worms at sites where contamination was suspected to have taken place. Average bioaccumulation factors indicated that Hg is the metal that is most readily available for bioaccumulation, followed by Cu, Zn and Mn. All of these metals were bioconcentrated in the tissues of the test chironomids, while levels of Fe, Ni, Cr and Pb were found to be lower in the organisms than in the sediments. Although many of the chemical fractions were found to correlate significantly with the uptake of the different metals, the best overall correlation existed between the bioaccumulated metal and the total non-residual fraction. In fact, the sum of the first four steps of the Tessier-scheme correlated significantly with the bioaccumulated metal for all elements considered in the calculation, except for Pb. Additionally, the predictions made by the AVS model were found to be useful in justifying the behaviour and accumulation patterns of Hg, Zn and Cu at certain sites. The correlations and bioavailability clearly differed spatially, temporally and among the different elements. It is therefore suggested that prediction of the bioavailability and subsequent uptake of sediment-bound metals will require as many chemical and environmental factors as possible, and should include bioaccumulation and toxicity testing in order to examine the validity and completeness of these predictions.
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Sepato, Obone. "Statistical and wavelet analysis of density and magnetic susceptibility data from the Bushveld Complex, South Africa." Thesis, 2015. http://hdl.handle.net/10539/18528.
Full textAbstract:
A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science.
Johannesburg, 2015The Bushveld Complex (BC) is the largest known layered intrusion. This suite of rock crop out in northern South Africa to form the Western, Eastern and Northern Limbs. Most research carried out focuses on the mineralized horizons in the Rustenburg Layered Suite (RLS) of the BC. This study presents a large database of wireline geophysical logs across a substantive part of the stratigraphy of the RLS. These consist of density and magnetic susceptibility datasets sampled at 1 cm. The major lithologies of the RLS intersected in the boreholes presented are gabbro, gabbronorite, norite and anorthosite whose density histograms reveal that they are predominantly normally distributed, with density averages of 2.86-2.91 g/cm3. The lithologies consist of mainly two minerals, pyroxene and plagioclase. In general, the average density increases with an increase in pyroxene. The distribution of the magnetic susceptibility for these lithologies has a large variation from SI to 13.2 SI, which is typical of layered intrusions. Susceptibility distributions are also multi-modal, asymmetric and not normally distributed, which makes the average magnetic susceptibilities less representative of the lithologies. Cross-correlation plots between density and magnetic susceptibility for several boreholes show that the above-mentioned lithologies form clusters (circular to elliptical), which typically overlap. This has been further investigated using k-means classification, to automatically detect these clusters in the cross-correlation plots and to compare these with those created by lithologies. The comparison shows some degree of correlation, implying that physical properties can be used to identify lithologies. This is particularly true for the Eastern Limb. However the classification has not been effective in all of the boreholes and often becomes complicated and an inaccurate representation of lithology log. This occurs in boreholes in which there is an overlap in the physical properties of the abovementioned lithologies. Analysis on the density and magnetic susceptibility data has also been carried out using wavelet analysis at individual locations across the BC. This has revealed multi-scale cyclicity in all of the boreholes studied, which is attributed to subtle layering created by variations in modal proportions between plagioclase and pyroxene. In addition to this, since layering is generally ubiquitous across layered intrusions, this cyclicity can be assumed to be present across the entire BC. This technique may become increasingly important should the cyclicity in physical property data correlate with reversals in fractionation trends since this may suggest zones of magma addition, whose thickness or III volumes can be quantified using wavelet analysis. This could be an important contribution since the current perspective on magma addition in the RLS is that four major additions have formed this 8 km thick suite of rocks, as opposed to smaller periodic influxes of magma. Wavelet-based semblance analysis has been used to compare the wavelengths at which the cyclicity occurs across boreholes. A comparison of wavelengths of this cyclicity shows that boreholes in the northern Western Limb show positive correlation in the density data at wavelengths >160 m and 20-60 m, while those further south show correlations at wavelengths of 120-200 m and 60-80 m. Boreholes of the Eastern Limb show positive correlation in the density and magnetic susceptibility data at wavelengths of 10-20 m, 20-30 m and 5m. These positive correlations across boreholes in density and magnetic susceptibility respectively, may imply that cyclicity may be produced by a chamber-wide process for several kilometres of the BC.
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McClung, Craig Randall. "Basin analysis of the Mesoproterozoic Bushmanland group of the Namaqua Metamorphic Province, South Africa." Thesis, 2008. http://hdl.handle.net/10210/610.
Full textAbstract:
The Mesoproterozoic Bushmanland Subprovince of northwestern South Africa forms the western continuation of the transcontinental Namaqua-Natal Metamorphic Province, a crustal domain affected by the 1020-1220 Ma Namaquan Orogeny. Cross-cut by several large faults, the Bushmanland Subprovince can be subdivided into a southern Garies Terrain and northern Aggeneys Terrain. The supracrustal rocks of the Aggeneys Terrain (i.e. Bushmanland Group), comprise a thin (<1 km thick) metavolcano-sedimentary succession composed of a very consistent, shallow marine duplex of sandstone-shale to chemogenic metasedimentary and metavolcanic rocks that have undergone multiple phases of deformation and metamorphism. Since the discovery of the Broken Hill-type (BHT) mineralization in the Aggeneys-Gamsberg district (~440 Mt, 5.2% Cu+Zn+Pb) in the early 1970’s, controversy has persisted regarding the stratigraphy of the Bushmanland Group, its lateral correlation throughout the Aggeneys Terrain, environment and age of deposition, as well as classification and origin of its base-metal sulfide ± barite deposits. For these reasons, the present study primarily focuses on two aims, namely: (1) regionally based comprehensive lithostratigraphic, geochemical and geochronologic analysis of the Bushmanland Group to be used in the construction of a basin model; and (2) petrographic and geochemical analyses of Fe-Mn-rich rocks and barites to determine if they are related to base-metal mineralization and if so, to what extent. New lithostratigraphic data for the Bushmanland Group indicate that it can be subdivided into two subgroups and thirteen formations that are directly correlatable throughout the terrain as well as similar supracrustal successions in neighboring portions of the Namaqua Metamorphic Province. The base of the Bushmanland Group (Wortel Subgroup) comprises a thin (250-350 m thick) sequence of interbedded upward-coarsening psammo-pelitic schists and mature quartzite (i.e. meta-orthoquartzites) of the Namies Schist Fm., Pella Quartzite Fm., Bloemhoek Fm. and laterally equivalent Kangnas Fm. In contrast, the metasedimentary rocks of the unconformably overlying Kouboom Subgroup can be separated into facies terrains divided by the Pofadder-Tantalite Valley Shear Zone (PTV Shear Zone). West of the PTV Shear Zone the Kouboom Subgroup is characterized by a thin (205-225 m thick) succession of interbedded mature quartzites and pelitic schists. East of PTV Shear Zone the Kouboom Subgroup encompasses a thick (~1250 m thick) succession of calc-silicate rocks hosted by biotite to calc-silicate-rich schists and metagreywackes. The Koeris Fm., a variably thick (0-650 m) succession of psammitic schists, metaconglomerates and ortho-amphibolites unconformably overlies the Kouboom Subgroup. Geochemical provenance and detrital zircon core populations of the Wortel Subgroup suggest the metasedimentary rocks were derived from the Paleoproterozoic continental island arc rocks of the Vioolsdrift Intrusive Suite and Gladkop Suite, as well as an unidentified sedimentary/metasedimentary succession. Deposition took place in a passive continental margin environment between 1140 to 1650 Ma. In contrast, the unconformably overlying Kouboom Subgroup is characterized by larger plutonic derived zircons of the basement rocks to the Orange River Group, suggesting deposition in a tectonically active environment marked by repeated periods of tectonic uplift. In addition, new age constraints reveal that deposition in the upper part of the Kouboom Subgroup (possibly upper part of the Gams Fm.) was synchronous with emplacement of the Little Namaqualand Suite (~1190 Ma) into the lower portions, i.e. Wortel Subgroup, of the Bushmanland Group. The geochemical attributes and detrital zircon populations of metagreywackes from the Driekop Fm. suggest they were eroded from the newly exposed, i.e. fresh to poorly weathered, intrusions of the Little Namaqualand Suite, indicating a renewed period of tectonic uplift. Lastly, unlike the other lithologic units of the Bushmanland Group, the Koeris Fm. exhibits four detrital zircon age populations at 1125-1325, 1605-1695, 1730-1910 and 1935-2075 Ma. The older sub-populations indicate sediment derivation from various units of the Richtersveld Subprovince and Steinkopf Domain, while the younger sub-populations suggest derivation from various units in the Rehoboth Inlier of Namibia and the Gordonia Terrain to the east. The provenance signature of the younger subpopulation implies that deposition of the Koeris Fm. occurred after continental collision between the Rehoboth Inlier-Kaapvaal Craton and the Namaqua Metamorphic Province. With regards to the base-metal deposits of the Aggeneys-Gamsberg district, petrographic and geochemical analysis of the Bushmanland Group Fe-Mn-rich rocks suggests that they can be subdivided into several types: (1) primary Fe-Mn-rich metasedimentary rocks; (2) magnetite-amphibole-rich Fe-Mn-rich rocks; (3) coticules; and (4) epigenetic Fe-Mn-rich rocks. Primary Fe-Mn-rich metasedimentary rocks occur throughout the western and central portions of the study area and appear to have been formed through the deposition of Fe-Mn-rich hydrogenous precipitates in areas of localized sediment starvation. However, as illustrated by the primary Fe-Mn-rich metasedimentary rocks of the Lemoenpoort prospect, a syn-diagenetic, hot (>250°C), metalliferous hydrothermal fluids infiltrated and altered these hydrogenous Fe-Mnrich metasedimentary rocks, resulting in the deposition of base-metal sulfides, formation of magnetite-amphibolite-rich Fe-Mn-rich rocks, as well as hydrothermal alteration of the siliciclastic wall rocks to form coticules. The spatial restriction of epigenetic Fe-Mn-rich rocks to shear zones, high Fe2O3 T (ca. 65 wt %), low ΣREE (ca. 13 ppm), presence of recrystallized quartz crystals, elevated concentration of Cu in some occurrences and general similarities with some hydrothermal iron/iron-oxide copper-gold (IOCG) deposits, suggests that the epigenetic Fe-Mn-rich rocks may have formed during prograde metamorphism. Low concentrations of SrO (0.5 ± 0.2 wt %), highly radiogenic Sr/ Sr ratios (0.7164 ± 0.0028), elevated δ S (27.3 ± 4.9 ‰) and δ O (7.7 ± 3.1 ‰) values in the barites, as compared to contemporaneous Mesoproterozoic seawater, suggests precipitation of stratiform and stratabound barite layers in the Bushmanland Group occurred through mixing of an evolved continental crustal source and contemporaneous seawater sulfate, 87 86 34 18 modified by bacterial sulfate reduction. Most importantly, δ O values suggest possible minimum temperatures of formation ranging from 18 <150°C for the Gamsberg deposit to >250°C for occurrences in the Aggeneys area. These obvious differences in temperature of formation are in good agreement with the Cu-rich, Ba-poor nature of the sulfide mineralization characteristic of the Aggeneys deposits versus the Cu-poor, Ba-rich character of the Gamsberg deposit. In conjunction with this, the isotopic and petrographic arguments favor a sub-seafloor replacement model for the stratabound barite occurrences of the Aggeneys deposits, while at Gamsberg, deposition at the sediment-water interface as a true sedimentary exhalite appears more acceptable. Data obtained in the present study, combined with the results of previous investigations can be used to develop a comprehensive model for the geological evolution of the Aggeneys Terrain and Namaqua Metamorphic Province. The tectono-sedimentary evolution of the Aggeneys Terrain and Namaqua Metamorphic Province is marked by two important tectonic events separated by an episode of tectonic quiescence. Extrusion and deposition of the metavolcano-sedimentary rocks of the Orange River Group at 1908 Ma marks the start of the Orange River Orogeny. vii Prior to emplacement of the Vioolsdrift Intrusive Suite, the Orange River Group appears to have undergone a period of folding and low-grade metamorphism [D1/M1] that was subsequently followed by emplacement of the Main Phase Vioolsdrift Intrusive Suite roughly dated at 1890 Ma. Rapidly following emplacement of these intrusions, the lower crustal rocks of the Richtersveld Subprovince underwent a second, higher, amphibolite-facies metamorphic event [M1B] from 1870-1840 Ma. This event may have resulted in lower crustal melting and emplacement of the Gladkop Suite into an unknown package of metasediments or metasedimentary rocks south of the present day Orange River at roughly 1820 Ma. The Gladkop Suite was subsequently subjected to high-grade metamorphism at 1800 Ma. The Orange River Orogeny was terminated by emplacement of the Late Phase Vioolsdrift Intrusive Suite at approximately 1765 Ma and later northward-directed thrusting. Following termination of the Orange River Orogeny, deposition of the Bushmanland Group began in a tectonically stable environment marked by punctuated periods of tectonic activity that lasted until emplacement of the Little Namaqualand Suite at 1190 Ma. The detrital zircon populations of the Pella Quartzite Fm. and Koeris Fm. support (a) regional correlation of these stratigraphic units throughout the study area, (b) confirms sediment derivation from various local source terrains and (c) suggests a maximum depositional age of 1650 Ma. Furthermore, new age constraints reveal initiation of the O’okiepian Episode (Namaquan Orogeny), characterized by regional-scale mid- to high-grade contact metamorphism, was synchronous with emplacement of the Little Namaqualand Suite and deposition of the upper Kouboom Subgroup. Furthermore, the detrital zircon populations for the Driekop Fm. (upper Kouboom Subgroup) contain a large population of 1190 Ma (i.e. O’okiepian-age) detrital cores, suggesting a renewed period of tectonic uplift. Analogously, age constraints for the Koeris Fm. indicate a maximum depositional age of 1130 Ma, as well as derivation from a number of local and exotic source terrains indicating that deposition of the Koeris Fm. must have occurred in response to continental collision between the Rehoboth Inlier-Kaapvaal Craton and the Namaqua Metamorphic Province. Furthermore, these new age constraints also constrain the timing of D2-D3 deformation to between 1130-1080 Ma and regional peak metamorphism to 1020- 1040 Ma.Prof. N.J. Beukes Prof. J. Gutzmer
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Mashabela, Sello. "Analysis of pre-impact and impact-induced geological structures in the northern collar of the Vredefort Dome, South Africa." Thesis, 2016. http://hdl.handle.net/10539/21696.
Full textAbstract:
A Dissertation submitted to the Faculty of Science, University of the Witwatersrand; in fulfilment of the requirements for the degree of Master of Science. Johannesburg
August 2016.Rocks of the Neoarchaean Witwatersrand Supergroup exposed in the collar of the impact-induced 2.02 Ga Vredefort Dome exhibit complex geological structures. These structures are generally considered to have been formed by the Vredefort impact event, through rapid deformations on time scales of seconds to minutes associated with the relatively brief impact processes. However, geological mapping of the structures and petrographic analysis from the northern collar of the dome show that the collar hosts at least three generations of pre-impact structures. In contrast to impact-induced structures, these pre-impact structures indicate slow and progressive deformations that are uncharacteristic of impacts. The pre-impact deformations comprise: (a) an extensional D1 deformation characterised by listric faults up to kilometre-scale; (b) Syn-metamorphic (M2(NC)) D2 ductile deformation characterised by regional S2 foliation, which locally indicates northwest-directed vergence; and (c) D3 deformation that crenulated the pre-existing S2 foliation (S3). Pre-impact structures can be distinguished from impact-induced structures by: (1) difference in the geometry and sense of slip between D1 faults and D4 impact-induced faults; and (2) crosscutting relationships between impact-induced D4 features and D2 and D3 pre-impact features. In their present (rotated) orientation, the D1 faults exhibit an apparent strike-slip separation, which translates to normal-slip fault geometries when impact-induced overturning of strata is undone. Displacement affects the Witwatersrand and Ventersdorp Supergroup rocks but no offset is observed of the base of the Transvaal Supergroup. The faults also exhibit a listric geometry, curving into parallelism with bedding in the lower West Rand Group. In their restored orientation, faults define half-graben and horst blocks, synthetic and antithetic faults, and rollover and drag folds, which are typical for extensional tectonics. These geometries and crosscutting relationships of the D1 faults are similar to that of the Neoarchaean listric faults described in the Witwatersrand goldfields and the wider Kaapvaal craton, that exhibit a general west-side-down sense of slip (2.70-2.64 Ga Hlukana-Platberg extensional event). Metamorphic grade in the study area decreases from amphibolite- to greenschist-facies away from the centre of the dome. These are largely M2(NC) metamorphic assemblages that are attributed to elevated regional heat flow related to 2.06 Ga Bushveld magmatism. There is some evidence that M2(NC) metamorphic mineral assemblages developed along the same stratigraphic units differ across the large D1 faults, indicating the pre-impact nature of the D1 faults and implying that the M2(NC) metamorphism occurred after the Hlukana-Platberg event. Also, M2(NC) assemblages are syn-tectonic to the S2 foliation hosted in metapelite units of the West Rand Group and knotted quartzite horizons of the Central Rand Group. The S2 foliation is attributed to the post-Transvaal Supergroup, compressional, Ukubambana Event. Crosscutting relationships in the study area indicate a deformational period of 2.06 Ga to no less than 2.02 Ga. The northwest-directed vergence exhibited by the S2 foliation is broadly consistent with the regional, general north-directed, vergence exhibited by post-Transvaal Supergroup foliation developed in the northeastern collar and the Johannesburg Dome. The S2 foliation and M2(NC) mineral assemblages are crosscut by D4 pseudotachylitic breccia, micro-faults and kinks, and M4(NC) metamorphic features associated with the impact.
LG2017
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Wieland, Frank Wolf. "Structural analysis of impact-related deformation in the collar rocks of the Vredefort Dome, South Africa." Thesis, 2008. http://hdl.handle.net/10539/5748.
Full textAbstract:
The Vredefort Dome is located southwest of Johannesburg, South Africa, and represents the deeply eroded remnant of the central uplift of the world’s largest known impact structure, with an estimated diameter of ~300 km. The Vredefort impact structure is also the oldest known impact structure on Earth (~2.02 Ga). The Vredefort Dome comprises an ~40 km wide core of Archaean basement gneisses and an ~20 km wide collar of subvertical to overturned Late Archaean to Palaeoproterozoic supracrustal strata.
This project presents the results of Landsat-TM and aerial photograph analysis, as well as field mapping of Witwatersrand Supergroup metasedimentary strata in the collar of the Vredefort Dome. The aim of this study was to investigate the structures (such as folds, faults, fractures), at all scales, and other deformation features (such as shatter cones and pseudotachylitic breccias) in the field area, and to establish geometric and temporal relationships between these features with regard to the impact cratering process. This study revealed a highly heterogeneous internal structure of the collar involving folds, faults, fractures and melt breccias that are interpreted as the product of shock deformation and central uplift formation during the Vredefort impact event. Broadly radially-oriented symmetric and asymmetric folds, with wavelengths from tens of metres to kilometres, and conjugate radial to oblique faults with strike-slip displacements of, typically, tens to hundreds of metres accommodated tangential shortening of the collar of the dome that decreased from ~17 %, at a radial distance from the dome centre of 21 km, to <5 % at a radial distance of 29 km. Ubiquitous shear fractures containing pseudotachylitic breccia, particularly in the metapelitic units, display variable local slip senses consistent with either tangential shortening or tangential extension; however, it is uncertain whether they formed at the same time as the larger faults during the rise of the central uplift or earlier, during the shock compression phase of cratering.
Contrary to the findings about shatter cones of some earlier workers in the Vredefort structure, the Vredefort cone fractures do not show uniform apex orientations at any given outcrop, nor do small cones show a pattern consistent with the previously postulated “master cone” concept. The model of simple back-rotation of the strata to a horizontal pre-impact position also does not lead to a uniform centripetal-upward orientation of the cone apices. Striation patterns on the cone surfaces are variable, ranging from typically diverging, i.e., branching off the cone apex, to subparallel to parallel on almost flat surfaces. Striation angles on shatter cones do not increase with distance from the crater centre, as suggested previously. Instead, individual outcrops present a range of such striation angles, and a more irregular distribution of striation angle values with regard to the distance from the crater centre suggests localised controls involving the nature and shape of various heterogeneities in the target rock on this aspect of cone morphology.
On the basis of the observations made during this study on small-scale structures in the collar of the Vredefort Dome, the relationship of shatter cones with curviplanar fractures (multipli-striated joint sets - MSJS) is confirmed. Pervasive, metre-scale tensile fractures crosscut shatter cones and appear to have formed after the closely-spaced MSJ-type fractures. The results of this study indicate that none of the existing models is able to explain all characteristics of shatter cones fully; therefore, a combination of aspects of the different models may currently be the best possible way to explain the formation and origin of shatter cones, and the formation of the related MSJ and their characteristic aspects (e.g., curviplanar shape, melt formation, etc.). The observed variety of shatter cone orientations, surface morphology and striation geometry in the dome concurs broadly with the results of some previous studies. The abundance of striated surfaces along closely-spaced sets of fractures (MSJ) observed in this study can be reconciled with reflection/scattering of a fast propagating wave at heterogeneities in the target rocks, as proposed by recent studies. This would mean that closely-spaced fractures and shatter cones were not formed during shock compression, as widely postulated in the past, but immediately after the passage of the shock wave, by the interference of the scattered elastic wave and the tensional hoop stress that develops behind the shock front.
In addition to shatter cones, quartzite units show two other fracture types – a centimetre-spaced rhomboidal to orthogonal type that may be the product of shock-induced deformation and related to the formation of shatter cones, and later joints accomplishing tangential and radial extension. The occurrence of pseudotachylitic breccia within some of these later joints confirms the general impact timing of these features.
Pseudotachylitic breccias in the collar rocks occur as up to several centimetre-wide veins with variable orientations to the bedding and as more voluminous pods and networks in zones of structural complexity, such as the hinges of large-scale folds and along large-scale faults, as well as locally, at lithological interfaces. In places, tension gash arrays along thin veins are observed indicating that movement occurred along these planes. Initial cooling calculations for pseudotachylitic breccias of different widths and compositions (metapelite or quartzite) suggest that thick veins (<10 cm) could have stayed molten over the entire duration of crater development (at least 10 minutes), making it possible for shock-induced melts to intrude dilational sites, such as fold hinges and extensional fractures, during the formation and subsequent collapse of the central uplift. Intrusion of such melts may also have lubricated movements along brittle and ductile structures. Thus, the presence of both shock- and friction-generated melts is likely in the collar of the Vredefort Dome.
Based on the spatial and geometric relationship between the structures and other deformation features observed in the collar rocks of the Vredefort Dome, it is possible to establish a temporal sequence of deformation events. Shatter cones and related closely-spaced fractures were formed during the contact/compression phase of the cratering process. The formation of at least some shock-induced pseudotachylitic breccia also belongs into this phase. Large-scale folds and faults and friction-generated melts can be related to the initial formation of the central uplift and extensional joints to the subsequent collapse of the central uplift.
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Simpson, Elizabeth Anne. "The role of sulphate-reducing bacteria in mercury-contaminated estuarine sediments : a case study of Durban Bay." Thesis, 2003. http://hdl.handle.net/10321/2017.
Full textAbstract:
Dissertation submitted in compliance with the requirements for the Master's Degree in Technology: Biotechnology, Durban Insititute of Technology, 2003.Stimulated by the findings of international researchers, that the sulfate-reducing microorganism Desulfovibrio desulfuricans could be incriminated in the process of mercury bio-methylation, it was decided to test this hypothesis on sediments from selected areas of Durban Bay where elevated levels of the bio-hazardous heavy metal had previously been detected. The Environmentek Division of the Council for Scientific and Industrial Research (Durban) is involved in an ongoing chemical assessment of heavy metal contamination (including levels of mercury) in the sediments of this estuary, but nothing is currently understood about the form in which mercury exists or the biological processes that could be determining its fate. The purpose of this project was to attempt to answer some of these questions. The study involved attempting to isolate, identify and quantify microorganisms of the species Desulfovibrio desulfuricans, Escherichia coli and Clostridium perfringens in one hundred and eighty sediment samples taken from three designated sites in the bay. Each sample was additionally analysed for total and methyl mercury and sulfate content, as well as a number of physical parameters. Based on the outcome of the initial survey, it was envisaged that further laboratory experimentation would be conducted to determine whether or not isolates were responsible for the production of the highly toxic organic mercury and whether this process was occurring in situ in the sediments. The findings of this project were contrary to what had been expected. Total mercury concentrations (apart from one instance) did not appear to be appreciably elevated in the areas under study. Similarly, the levels of methyl mercury were fourrd to be either diminished or absent. Numbers of D. desulfuricans were low and not uniformly distributed throughout the sediments. Cl. perfringens was more in evidence, but counts were not perceptibly increased. Sulfate levels were consistently high, indicating significantly impaired rates of sulfate reduction. Difficulty experienced in sub-culturing
M
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Hoosen, Zayd Goolam. "Defining the spectral characteristics of rocks within the Mambulu Complex, Natal Belt, South Africa." Thesis, 2012. http://hdl.handle.net/10413/9739.
Full textAbstract:
Field and laboratory spectroscopy are sub-fields of remote sensing, where the radiometric data of materials are individually measured either where the materials occur in situ or in a controlled laboratory environment. Both applications require the use of a spectroradiometer to record this reflected electromagnetic radiation. The spectral properties of rocks from the Mambulu Complex in the Natal Belt have not been studied previously. Four dominant rock types, namely, massif-type anorthosite, leuco-gabbro, pyroxenite and magnetitite were sampled from the Mambulu Complex and their spectral reflectances measured. Absorption features were determined after continuum removal was applied to the spectra.
Anorthosite showed absorption features at 480-490, 592, 603, 608, 627-726, 765, 1410, 1905-1955, 2200, 2250 and 2330nm. For leuco-gabbro absorption features were observed at 481, 950-1010, 1407, 1917, 2206, 2252, and 2300-2340nm. Magnetitite displayed absorption features at 414, 460-515, 620-715, 982, 1380-1480, 1800, 1905-1930 and 2145-2330nm. For medium-grained pyroxenite absorption features were present at 410-420, 483, 680, 977-993, 1410-1415, 1800, 1920, 2205, 2250, 2307, 2400 and 2430nm. Coarse-grained pyroxenite showed absorption features at 460-727, 979, 1000, 1401, 1422, 1800, 1913, 1930, 2203, 2258, 2321, 2388 and 2421nm. ANOVAs and Bonferroni tests were applied to the spectral data to calculate significant spectral differences and between which pairs of rocks these significant differences occurred. Results showed that there were significant spectral differences between all the rock types of the Mambulu Complex. The variability of spectral characteristics within rock species was attributed to the difference in composition of fresh and weathered surfaces; and the significant spectral differences between rock samples can be attributed primarily to differences in mineral composition.Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2012.
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Schiller, Jeffrey Christopher. "Structural geology, metamorphism and origin of the Kanmantoo Copper deposit, South Australia / by Jeffrey Christopher Schiller." 2000. http://hdl.handle.net/2440/19902.
Full textAbstract:
Appendices 5 and 6 are made available in CD-ROM format.Includes copies of articles co-authored by the author during the preparation of this thesis as appendix 7.
14 maps (some folded, some col.); inserted in back pocket.
Includes bibliographical references (leaves 242-264).
System requirements for accompanying CD-ROM: Macintosh of IBM compatible computer. Other requirements: Adobe Acrobat Reader.
[15], 264 leaves : ill. (some col.), maps ; 30 cm. + 1 computer optical disk (4 3/4 in.)
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
On the basis of the present study it is concluded that there is no firm evidence that the bulk of the mineralisation is pre-metamorphic, although the possibility has not been excluded.
Thesis (Ph.D.)--Adelaide University, Dept. of Geology and Geophysics, 2001
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"On the engineering geology of granite saprolite and its significance to the construction of Injaka Dam, South Africa." Thesis, 2004. http://hdl.handle.net/10413/2406.
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The intention of this work is to provide a deeper understanding of the engineering geological behaviour of granite saprolite and how this affects the engineering of such material, with specific reference to the construction of Injaka Dam in the north eastern portion of South Africa Whilst extensive investigation of weathered granites has been carried out internationally, very little detailed research on the nature of this material is documented locally. The construction of Injaka Dam afforded the opportunity to investigate the saprolite in detail. This study was initially submitted to the Department of Geology and Applied Geology at the University of Natal, Durban (renamed the University of KwaZulu-Natal in 2004) to fulfill the requirement of a Master of Science degree in 200 I. Following this submission, and supported by recommendations made by the external examiners and the project supervisor, it was agreed to upgrade the work and submit this thesis for the degree of Doctor of Philosophy. Intensive chemical weathering of granite at Injaka Dam site has resulted in the formation of thick saprolitic deposits overlying the weathered bedrock. The granite forms part of the 3 075 Ma Nelspruit Suite which has been intersected by the African erosion surface. The extensive, multicyclic period of weathering and erosion that formed this surface has resulted in deep (up to 35 m) chemical weathering of the underlying bedrock in this area. The construction of Injaka Dam on this material necessitated a thorough engineering geological investigation to understand the nature of the weathering and the possible influences it exerts on the engineering behaviour of the saprolite. This was accomplished by analysing the weathering of the granite and relating the effects of these weathering processes and changes to the engineering behaviour of the material. By applying various chemical and mineralogical indices to the weathered granite, the intensity of weathering and related changes could be quantified and compared with the engineering behaviour of the material. This was achieved by applying a series of engineering indices to the material and relating these to the quantified weathering changes. In this way tentative extrapolation of the engineering behaviour of the material could be gained and used to predict engineering performance. The resultant effects of the engineering behaviour of the material on the design and construction of the dam are also discussed.Thesis (Ph.D.)-University of KwaZulu- Natal, 2004.
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Sukdeo, Prisha. "A study of the natural and anthropogenic impacts on the sediment and water quality of the middle and lower Mvoti River System, KwaZulu-Natal, South Africa." Thesis, 2010. http://hdl.handle.net/10413/5361.
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This dissertation focussed on the Mvoti River system in KwaZulu-Natal, an important
resource for the numerous towns and villages along its course. Catchment activities are
varied with agriculture being the predominant activity, and industrial activities common in the
lower catchment. The Mvoti River is intensively utilized, especially in its lower reaches, to the
extent that it is referred to as a ‘working river’. Modifications of the chemical and physical
characteristics of the system, and consequently the biological characteristics, have led to
degradation of the system such that the functioning of the lower river has deteriorated in
comparison to that of its pre-disturbance condition. There are three main aspects of the Mvoti
system around which this dissertation is based, namely, water quality, geochemistry, and
conservation of the system.
The results of the water quality survey of the estuary revealed that the system is presently
experiencing water which is of an inferior quality. Compared against the South African water
quality standards, a majority of the parameters exceed acceptable limits and are likely to
present negative impacts on aquatic health and potentially human health. Comparison of
current results, and water quality data for the system dating back to 1964, revealed that this
degradation is not new to the system, and the Mvoti Estuary has in fact been experiencing
continued deterioration over the years.
The second part of this study investigated heavy metal presence in the sediments of the
lower system and elemental presence and distribution in the surface sediments of the middle
and lower River respectively. Results indicated that even though selected heavy metals are
present, they are of concentrations lower than those of two other South African and two other
international systems they were compared with.
Enrichment and contamination assessments reveal that contaminants are in all probability
present as a result of anthropogenic sources. However, distribution patterns which show
highest levels just after effluent disposal sites suggest that the contamination is presumably
human-induced and, the predominance of larger grained sediments that do not have high
adsorption capacities, suggest that contaminants are readily remobilized into the water
column.
The final part of this research investigates other environmental problems, and causes, both
natural and anthropogenic, experienced by the estuary system. These stresses include poor
water quality, reduced water quantity, sedimentation, alien vegetation invasions and loss of
biodiversity. Strategies to address these issues are proposed, with the intention of improving
the condition of the estuary. This is an attempt at ecological restoration, to restore the
estuary to a condition as close to as possible, to its pre-disturbance condition. These
strategies include controlling abstraction and discharge, eradicating alien vegetation,
controlling sandmining, and improving the overall quality of the system. Also proposed is an
estuary management plan (EMP) for the Mvoti system, as there is currently no plan of such a
nature in place. The EMP will aid restoration attempts, increase public awareness, and via
post-project monitoring and evaluation ensure the success and sustainability of any future
projects. Significantly, the adoption of an EMP will be a major step towards the rehabilitation,
conservation and protection of this already degraded system.Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2010.
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De, Lemos Hugo Jose. "A critical analysis using remote sensing and GIS techniques for spatial distribution and macro-morphological analyses of rockfalls in the Golden Gate Highlands National Park, South Africa." Thesis, 2015. http://hdl.handle.net/10539/16818.
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A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. 11/30/2013.A variety of mass movement and depositional geomorphic phenomena in the Golden Gate Highlands National Park have been described in the literature over the past few decades, yet notably, the prominent rockfalls remain understudied. The objective of the MSc study is to undertake detailed mapping of the GGHNP rockfalls, and in so doing ascertain a better understanding of their macro-morphologies, associated spatial-size dynamics and relationships to lithology, using both field-based and desktop image processing techniques. Ground truthing, using the highest possible resolution achievable through differential GPS (DGPS) and field measurements with an accuracy of cm to mm, serves to quantify the accuracy of mapping rockfall phenomena through 0.5 m GSD colour aerial imagery. In addition, field measurements are used as inputs for feature extraction, such that rockfalls associated with the Clarens, Elliot and Molteno Formation Sandstones may be defined using object orientated classification techniques. The dimensions, orientation and absolute coordinates of rockfalls for select representative sites were captured using both field based and desktop techniques. The rockfall coordinates were taken at the midpoint of each measured rock using a DGPS, with an accuracy of ~ 2 cm on the x, y and z axis. Object Based Image Analysis (OBIA) of Clarens and Molteno Fm. rockfalls was performed successfully using ground-truthed rockfall measurements to guide the creation of segmentation and classification rulesets. Multiple linear regression modelling can be used to model rockfall characteristics from ground-truthing with remotely sensed imagery, albeit to a very limited extent. Elliot Formation rockfalls could not be mapped and analysed mainly due to resolution limitations. Uni- and bi-variate statistics show promise in interpreting rockfall distribution and weighting with environmental variables derived from a DEM and geological vector. Point density analyses found that for the entire GGHNP ~2 and ~4 rockfalls are found per Km² of Clarens and Molteno Formation rockfall areas
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Sepuru, Terrence Koena. "Assessing the use of multispectra remote sensing in mapping the spatio-temporal variations of soil erosion in Sekhukhune District, South Africa." Thesis, 2018. http://hdl.handle.net/10386/2406.
Full textAbstract:
Thesis (M.Sc. (Geography)) --University of Limpopo, 2018Soil erosion, which is a critical component of land degradation, is one of the serious global environmental problems often threatening food security, water resources, and biodiversity. A comprehensive assessment and analysis of remote sensing applications in the spatial soil erosion mapping and monitoring over time and space is therefore, important for providing effective management and rehabilitation approaches at local, national and regional scales. The overall aim of the study was to assess the use of multispectral remote sensing sensors in mapping and monitoring the spatio-temporal variations in levels of soil erosion in the former homelands of Sekhukhune district, South Africa. Firstly, the effectiveness of the new and freely available moderate-resolution multispectral remote sensing data (Landsat 8 Operation Land Imager: OLI and Sentinel-2 Multi-Spectral Instrument: MSI) derived spectral bands, vegetation indices, and a combination of spectral bands and vegetation indices in mapping the spatio-temporal variation of soil erosion in the former homelands of Sekhukhune District, South Africa is compared. The study further determines the most optimal individual sensor variables that can accurately map soil erosion. The results showed that the integration of spectral bands and spectral vegetation indices yielded high soil erosion overall classification accuracies for both sensors. Sentinel-2 data produced an OA of 83, 81% whereas Landsat 8 has an OA of 82.86%. The study further established that Sentinel-2 MSI bands located in the NIR (0.785-0.900 μm), red edge (0.698-0.785μm) and SWIR (1.565-2.280 μm) regions were the most optimal for discriminating degraded soils from other land cover types. For Landsat 8 OLI, only the SWIR (1.560-2.300 μm), NIR (0.845-0.885 μm) region were selected as the best regions. Of the eighteen spectral vegetation indices computed, Normalized Difference Vegetation Index (NDVI) and Soil Adjusted Vegetation Index (SAVI) and Global Environmental Monitoring Index (GEMI) were selected as the most suitable for detecting and mapping soil erosion. Secondly, the study assessed soil erosion in the former homelands of Sekhukhune, South Africa by applying a time-series analysis (2002 and 2017), to track changes of areas affected by varying degrees of erosion. Specifically, the study assessed and mapped changes of eroded areas (wet and dry season), using multi-date Landsat products 8 OLI and 7 Enhanced Thematic Mapper (ETM+)). Additionally, the study used extracted eroded areas and overlay analysis was performed together with geology, slope and the Topographic Wetness Index (TWI) of the area under study to assess whether and to what extent the observed erosional trends can be explained. ii Time series analysis indicated that the dry season of 2002, experienced 16.61 % (224733 ha) of erosion whereas in 2017 19.71% was observed. A similar trend was also observed in the wet season. This work also indicates that the dominant geology type Lebowa granite: and Rustenburg layered its lithology strata experienced more erosional disturbances than other geological types. Slopes between 2-5% (Nearly level) experienced more erosion and vice-versa. On the hand, the relationship between TWI and eroded areas showed that much erosion occurred between 3 and 6 TWI values in all the seasons for the two different years, however, the dry season of 2002 had a slightly higher relationship and vice-versa. We, therefore, recommend use and integration of freely and readily available new and free generation broadband sensors, such as Landsat data and environmental variables if soil erosion has to be well documented for purposes of effective soil rehabilitation and conservation. Keywords: Food security Global changes, Land degradation, Land-based ecosystems, Land management practices, Satellite data, Soil conservation, Sustainable Development; Topographic Wetness Index; Time series analysis.