3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item An investigation into the mineralogy and processing characteristics of the Elsburg reefs at South Deep Gold Mine, South Africa(2024) Notole, ViweGold ores of the Witwatersrand Supergroup in South Africa are known to be amenable to metallurgical recovery through the process of cyanidation. However, the continuous decline in gold ore grade, increased environmental liability caused by residual cyanide in tailings and an increase in the complexity of ore composition calls for an alternative processing route. This is important to ensure that low-grade ore recovery is profitable while producing environmentally benign waste residue. Process mineralogy provides a systematic approach for the practical application of mineralogical knowledge, aiding ore characterisation and predictive behaviour, thus optimising how ores can best be mined, blended and processed. This study used mineralogical data and environmentally friendly leach reagent (i.e., glycine) to diagnose and predict processing characteristics of the composite Elsburg reefs at South Deep Gold Mine, South Africa. The mineralogy of these reefs is dominated by quartz and sulphide minerals, with pyrite, arsenopyrite, chalcopyrite and pyrrhotite being the common sulphides. More than 85% of gold in these reefs is locked or hosted in pyrite and quartz. The geochemistry shows high concentrations of siderophile (e.g., Cu, Ni and Co) and chalcophile (i.e., Cu and Zn) elements that can form stable complexes with glycine. A moderate to strong correlation of these elements (Cu, Co, Ni, Zn, etc.) with gold is conformable with the sulphide minerals-gold association. The poor liberation characteristics of Elsburg reefs ore and its geochemistry negatively influence gold recovery using glycine leaching. Sequential or multi-stage leaching is best to process ore with moderate to high Cu concentration and unliberated gold. The outcomes of this study demonstrate that Elsburg reefs gold ore responds well to sequential glycine leaching, with gold recoveries up to 95%, depending on which method or conditions are used. At low glycine dosage (e.g., 300 ppm), leaching duration of 50 hours, and ambient temperature (~23°C), bottle roll leaching of the Elsburg reefs yield low gold recovery (i.e., 30%), while at higher glycine dosage (e.g., 1500 ppm) and same leaching conditions (duration and temperature), a higher gold recovery (i.e., 41%) is attainable. Sequential leaching at a higher concentration of glycine (1500 ppm) with a leaching duration of 101 hours, yield cumulative gold recovery of up to 86%. Furthermore, at higher glycine concentration (1500 ppm) and elevated temperature (i.e., 40°C), Elsburg reefs yield considerably higher gold recovery (95%). The leaching solution was recharged at different time intervals from the beginning to the end of the leaching process. The increase in glycine was complemented by an increase in oxidant concentration (potassium permanganate). The ratio of potassium permanganate to glycine was kept at 2:1 (potassium permanganate: glycine).Item Fluid-rock interaction in carbonatite and alkaline composite intrusions and implications for rare earth element mineralization(2019) Ozturk, AnilThe Spitskop Igneous Complex is a carbonatite-alkaline silicate complex located 190 km northeast of Pretoria and 48 km east of Groblersdal in South Africa. It covers an area of 50 km2 and intruded into the Bushveld Complex on the Kaapvaal Craton at 1.3 Ga. It is considered a part of the Pilanesberg Alkaline Province, as it contains similar rock types such as nepheline syenites, ijolites and carbonatites and has a similar age. The carbonatite component of the Spitskop Complex consists primarily of dolomite carbonatite, calcite-dolomite carbonatite and calcite carbonatite with an apatite-rich zone. The outer part of the complex comprises alkaline rocks including ijolite and nepheline syenite, surrounded by the Rustenburg Layered Suite and the Lebowa Granite Suite of the Bushveld Complex. It is a unique complex, where both felsic and mafic fenites occur together. REE mineralization is hosted in carbonatites, however it is not considered an economic mineral deposit. This study characterizes the alteration stages that led to the formation of fenites and alkaline rocks, and the petrology and geochemistry of the Spitskop Complex. It shows that the fluids controlled the rare earth element content of Spitskop and affected the mobility of REE. The Spitskop Complex was mapped and samples were collected from different lithologies. Thin section petrology was used to determine the characteristic features and distribution of minerals. A total of 125 polished thin sections were studied using transmitted-reflected light microscopy and scanning electron microscopy (SEM). XRF and ICP-MS data of rocks have been obtained and the distribution of major-, trace- and rare earth elements of different lithologies were studied. The chemical composition of the fenitized Bushveld rocks have been compared with the unfenitized Bushveld rocks. The carbonatites all have similar major element concentrations except for CaO, MgO and MnO. The CaO and MgO concentrations reflect the type of carbonatite and the carbonatite mineralogy. Trace element and REE patterns of the different carbonatites are similar. The REE content of Spitskop carbonatites is up to 740 ppm. Nepheline syenites show metasomatic REE alteration patterns. Fenites are divided into two groups in the Spitskop Complex, mafic fenites and granite fenites. Mafic fenites represent metasomatized Upper Zone gabbro, whereas granite fenites represent metasomatized Nebo Granite. Moreover, granite fenites are subdivided into feldspar fenite, 4 which contains mostly feldspar; and quartz-feldspar fenite, which contains quartz and feldspar together. Mafic fenites are enriched in Na2O-K2O and P2O5 relative to the likely parental Upper Zone gabbros. Most of the trace element and all of the REE content of the mafic fenites are higher than the Upper Zone gabbros except Sc, V, Ni, Cu and U. Feldspar fenites are enriched in Na2O, K2O and MgO, and depleted in SiO2 compared to the parental Bushveld Granites. There are only some limited locations in the world where mafic and granitic rocks are extensively metasomatized together, therefore the Spitskop Complex is an ideal place to investigate the metasomatic geochemical processes. The mobility of the trace elements changes with increased fenitization. Nebo Granite has the highest trace elements concentrations, rather than in the quartz-feldspar fenite, with the feldspar fenite most depleted. However Cu, Sc and Eu are depleted in Nebo Granite. The REE data shows that the fenites compositionally lie between the unaltered Nebo Granite and the unaltered Upper Zone rocks. Fenitized Nebo Granite is depleted in REE and fenitized Upper Zone rocks are enriched in REE. The unaltered Upper Zone country rocks defines the lower REE boundary and the Nebo Granite defines the upper REE abundances. It is suggested that the metasomatic fluids caused a depletion of REE in the felsic rocks, whereas the same fluids caused an enrichment of REE in the mafic rocks. In mafic rocks the enrichment is dispersed through the whole rock across a broad zone and is therefore not economic. The data from thin section petrography and SEM suggests that the fenitization evolved in multiple steps at the Spitskop Complex. Alteration minerals show that there is a systematic change of minerals, from plagioclase to albite or nepheline, from olivine and orthopyroxene to clinopyroxene, from nepheline to analcite and from clinopyroxene to amphibole, which represent mafic fenites. Geochemical data, particularly REE patterns, suggests that the nepheline syenite at Spitskop is not a magmatic nepheline syenite, rather it is a product of fenitization. The REE patterns of the nepheline syenites are similar to the fenites of the Spitskop Complex and differ from other Pilanesberg nepheline syenites such as those in Pilanesberg, which are not fenitized. REE geochemistry also suggested that the syenites produced from fenitization (feldspar fenites) can be distinguished from magmatic syenite with the same REE patterns.Item Distribution of rare earth elements in the Epembe Carbonatite Dyke, Opuwo Area, Namibia(2019) Kapuka, Ester P.The Epembe carbonatite dyke at the Epembe Carbonatite-Syenite Complex in the Kunene region on the northwestern border of Namibia was emplaced along a northwest-trending fault zone, into syenites and nepheline syenites and extends for approximately 6.5 km in a northwest to southeast direction with a maximum outcrop width of 400 m. The Epembe carbonatite has a Mesoproterozoic age of 1184 ± 10 Ma which is slightly younger than their host nepheline syenites (1216 ± 2.4 Ma). Following the geological data collection and laboratory analysis of whole-rock samples [using optical microscopy, X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS)] the collected data was studied in detail in order to determine the geochemical composition of the Epembe carbonatite dyke. This research therefore presents new geochemical data for the Epembe carbonatite in order to describe the distribution and occurrence of rare earth elements of this dyke. The carbonatite displays a heterogeneous characteristic both texturally and mineralogically highlighting clear successions of at least three magmatic pulses. Irrespective of the changes, all carbonatite phases are inferred to be sourced from the same magma because they are typified by a similar geochemical signature of both major and trace element composition. They are characterised by high concentrations of calcium (CaO: 38.01 - 55.31 wt. %), phosphorus (P) (up to 18076), titanium (Ti) (up to 5122 ppm) strontium (Sr) (up to 12315 ppm) and niobium (Nb) with the (highest value of up to 2022 ppm ) alongside low concentrations of iron (FeO: 0.87 - 9.29 wt. %), magnesium (MgO: 0.19 – 1.33 wt. %) silica (SiO2: 1.30 – 10.89 wt. %) and total alkalis (K2O + Na2O < 2.0 wt. %) , hence they are regarded as one carbonatite dyke. The petrography and whole-rock element compositions of major elements have demonstrated the Epembe carbonatite is primarily made up of course-grained calcite (~92%) with a CaO+MgO+Fe2O3+MnO ratio of 0.93 relative abundances (in wt. %) and thus is classified as calcio or calcite carbonatite. The total REE content of Epembe carbonatite is high (406 – 912 ppm) with high LaN/YbN value (10.19 -28.49) and thus atypical of calcio-carbonatites. Chondrite normalized REE pattern for the carbonatite exhibit a strong steady decrease (negative slope) from LREEs to HREEs with a slight negative Eu anomaly but those are relatively low compared to global average calcio-carbonatites. Even though the Epembe carbonatite is enriched in Rare Earth Elements, there were no REE-bearing minerals observed at Epembe carbonatite except for monazite in trace amounts. Geochemical results show that the REE are either included in several accessory minerals such as apatite and pyrochlore and possibly in gangue minerals (i.e., silicates [including calcite and zircons] and carbonates) through enrichment processes related to fractional crystalisations and chemical substitution.Item Process mineralogy and extraction of rare earth elements from a beach placer deposit(2019) Moila, Awelani VeronicaRare earth elements (REE) are a group of the lanthanides and are significant in the world’s economic growth and modern technology market. This REE technological resource is globally distributed and highly monopolised in China. The global demand in REE led to China – “the leading economic producer of REE”, limiting its export quotas of the commodity, thus reducing the supply of REE. The decline in REE supply opened up opportunities for other countries to explore alternative and additional sources of REE. This research aims to investigate alternative sources of REE and to explore an efficient means of processing REE minerals from an existing beach placer deposit operation, currently being mined for titanium. Mineralogical characterisation and hydrometallurgical testwork were chosen for this study. The sample represented a tailings fraction from heavy mineral concentration. The sample was screened into four size classes namely; +212μm, –212+150μm, –150+106μm and –106μm. Each size class was mineralogically characterised. Mineralogy is an important factor in plant optimisation and process route predictions. In order to process REE efficiently, an upfront mineralogy is a necessity to reduce the rising hefty ore-processing costs. An integration of X-ray diffraction, optical microscopy, scanning electron microscopy (SEM), electron microprobe analysis (EMPA), automated SEM and bulk chemical analysis was employed in defining the mineralogical characteristics of the tailing sample. The mineralogical analysis of the tailing sample showed monazite as the prominent REE- bearing mineral, followed by zircon. Other minerals such as epidote, amphibole, rutile, quartz, leucoxene, titanite and almandine were identified in the sample. The results also revealed that the mineralogy of the sample varies per size fraction. The concentrations of REE in other minerals were confirmed in zircon, leucoxene, titanite and almandine by means of EMPA. The mineralogy findings showed that zircon and monazite are well liberated, with the majority of these minerals distributed in the–150+106μm and –106μm finer fractions. Approximately 50 mass% of the sample, constituting the finer fraction, has concentrated monazite and zircon. The naturally concentrated monazite and zircon in the finer size fractions showed that the fraction does not require ore upgrading and it is amenable to direct leaching. Subsequent to the mineralogical findings, the leaching testwork was carried out on the combined –150+106μm and –106μm finer fractions in three stages: caustic cracking, water leaching and HCl leaching. The leached products and residues were investigated for their REE extraction success. The extraction findings showed a 55% extraction efficiency of rare earth elements extracted from monazite only. The mineral zircon was identified as an alternative source of REE, apart from monazite, although processing of zircon proved to be inefficient.Item Pegmatites of the Cape cross-U is pegmatite belt, Namibia: structural, mineralogical, geochemical and mineral chemical characterization with implications for petrogenesis and mineralisation(2018) Fuchsloch, Warrick CThe Neoproterozoic Pan-African Damara Orogen in Namibia is host to a variety of mineral resources, most occurring within the metasedimentary and igneous lithologies of the inland branch of the orogen, known as the Damara Belt. Examples of economic deposits include base metals, semi-precious stones and rare-metal pegmatites hosting minerals such as cassiterite, columbitegroup minerals, petalite, spodumene, lepidolite and U-bearing phases. The Cape Cross-Uis pegmatite belt is one of several pegmatite belts within the Damara Belt, located in the Northern tectonostratigraphic Zone. The LCT-type pegmatites of the belt were divided into three different types based on characteristics, mineralogy and whole-rock geochemistry. The types from most abundant to least are: 1) metasediment-hosted, Nb-Ta-Snbearing, unzoned pegmatites, 2) granite-hosted, garnet-tourmaline-bearing, crudely zoned pegmatites and 3) metasediment-hosted, Li-bearing, complexly zoned pegmatites. To the southeast of Uis, the Nainais pegmatites occur within the Nainais-Kahero pegmatite belt and were studied for comparison to the Cape Cross-Uis pegmatites. They are similar in almost all aspects to the NbTa-Sn-bearing type pegmatites and were grouped together accordingly. Field characteristics and structural analyses of the pegmatites indicate an overall northeast trend of pegmatites in line with the belt-wide northeast regional lineation. Furthermore, the pegmatites intrude various Damaran structures, however, they are not co-genetic with these structures and cross-cutting relationships and a lack of micro- or macroscopic deformational features within pegmatites indicate an exclusively post-orogenic emplacement age. Regional mapping of the pegmatite types also indicates that there is no apparent mineralogical or whole-rock geochemical spatial relationship of pegmatites with resident granites. Whole-rock geochemistry of fine-grained border zones within pegmatites reveals that fractionation was the dominant process by which incompatible elements within the pegmatitic melt were enriched. Assimilation was discounted as a potential process in which elements such as Sn were incorporated into the pegmatitic magma as assimilation indicators such as MgO+FeO-CaO do not correlate with any trace elements. In addition, there is a mass balance problem since biotite schist country rocks on average show 70 ppm Sn and pegmatites may reach up to 1 wt% Sn in late-stage alteration zones such as greisens. Furthermore, the dominant morphologies of greisens indicate that late-stage, Cl-complexed, Sn- and possibly Ta-Nb-enriched fluids were trapped by larger feldspar crystals and therefore could not have remobilised Sn from country rocks in a leaching, circulating, hydrothermal system. Whole-rock geochemistry also shows that pegmatites and granites either follow completely different fractionation trends or overlap in fractionation trends, suggesting a decoupling of elements and preclusion from being coeval. Rare-earth elements confirm that a granite-pegmatite cogenetic relationship is unlikely since REE values of pegmatites (0.1-5 chondrite normalised) are two orders of magnitude lower than granites (10-100 chondrite normalised) where one would expect concentrations of incompatible elements in pegmatites to be far greater than in granites if a granite-parent, pegmatite-daughter type relationship is implied. In addition, a lack of pegmatite spatial association with granites supports this hypothesis. Fractionation trends and minor element substitution trends in CGM suggest that mineral competition for elements within the melt produced Fe-rich CGM phases over a wide range of T/(Ta+Nb) values (fractionation indicator in CGM; 0.03-0.96) which supports an LCT, Petalitesubtype pegmatite signature. Furthermore, the CGM mineral chemical data and textures of zonation patterns in CGM may indicate that Ta, Nb and Sn were complexed and subsequently enriched in a late-stage exsolved pegmatitic aqueous fluid, which led to economic mineralisation of cassiterite, CGM and tapiolite in greisenised zones within pegmatites. Additional evidence is shown by the elevated values of Ta, Nb and Sn in host rock metasomatic contact zones which are abundant in tourmaline. Tourmaline mineral chemistry reveals that assimilation played a negligible role in the element diversity of the pegmatites, supporting whole-rock geochemical data. Tourmaline compositions indicate that the pegmatite magmas went through a phase of mafic depletion and Fe-enrichment in the early stages of crystallisation. During an intermediate stage of magma evolution, early CGM stabilised and competed with tourmaline for Fe in the magma, subsequently decreasing Fe contents in tourmaline and increasing Al, Li and Mn (elbaitic compositions). Highly mafic tourmaline compositions from pegmatites are rare and most likely indicate a crustal anatexis petrogenetic model for the pegmatites of the Cape Cross-Uis pegmatite belt, confirming whole-rock geochemical and field observationItem Significance of liquid inclusions in the C-O-H fluid system of the upper zone, Bushveld Igneous Complex, South Africa(2018) Buthelezi, MusawenkosiFluid inclusions in the Upper Zone quartz of the Bellevue drillcore and quartz of the monzonite/two-feldspar granite from the Stoffberg area are studied by a suite of advanced high precision methods. The accessory magmatic quartz of the Bellevue drillcore samples hosts a complex suite of H2O-CO2-CH4 fluid inclusions which have thus far received very little attention. For the abundant quartz in the Stoffberg samples (quartz monzonite/two-feldspar granite) hosts a simple suite of H2O-NaCl, H2O-CaCl2 and H2O-MgCl2 fluid inclusions, which is yet to be described. CH4-rich fluid inclusions of the Bellevue drillcore (e.g. olivine ferrodiorite, quartz anorthosite, anorthosite and leucogabbronorite) can be shown based on fluid inclusion petrography to be mainly part of the primary fluid inclusion assemblage. Based on conducted study four types of fluids were identified in Bellevue drillcore, all of them separated during the crystallization of volatile-rich residual melt of original mafic magma, whilst in the Stoffberg samples only three types of fluids were identified and are likely to be derivatives of the later felsic melts, probably of crustal melts. The melting temperatures of the carbonic (CO2 ± CH4) of olivine ferrodiorites and leucogabbronorites, ranges from -59.7 to 56.8 ºC (mean = 58 ± 0.9 ºC; n=50), fluid inclusions, with their homogenization temperatures (TCO2) ranging from 18.8 to 30 ºC (28 ± 3.6 ºC). The number of carbonic (CO2 and CH4) fluid inclusions in the Bellevue drillcore suggests that the carbonic (CO2 and CH4) fluids played a significant role, by acting as a geochemical barrier in shallow magmatic systems, which is contrary to the generally accepted idea that carbonic fluids are generally not a major component in such magmatic systems as these fluids tend to escape from magma at relatively deep environments. For the Stoffberg samples there is no evidence for carbonic (CO2 and CH4) fluid inclusions, which may imply that (CO2 and CH4) fluids played no part during the crystallization and cooling of the Stoffberg rocks. The Ti-in-quartz geothermometry suggests that the maximum temperature of entrapment from about 677 ± 29 to 767 ± 18ºC and 738 ± 35 and 799 ± 22°C, at 3 kbar pressure, for the Bellevue core and Stoffberg samples, respectively. Based on the microthermometric, geochemical (Ti-in-quartz geothermometry) and petrographic evidence, the CH4 observed in the samples of the Bellevue drillcore was produced by respeciation of the C-O-H fluids via in situ phase separation (immiscibility of the fluids in the H2O-CO2-CH4 system) and probably the interaction of fluids with rocks during the late-stages of crystallization in the Bushveld Igneous Complex (BIC). This is further supported by the presence of graphite in H2O-CO2 bearing inclusions, in quartz anorthosite and leucogabbronorite. The lower melting temperature of aqueous-rich fluid inclusions, in olivine ferrodiorites and quartz anorthosites, suggest a later entrapment along cracks in quartz. This study further emphasizes the idea that the oxidation of reduced heterophase fluids could be the most important geochemical barrier caused the crystallization of solid mineral phases from heterophase fluids. The evidence presented in this study suggest that the Stoffberg material is unlikely to represent the most evolved part of the Rustenburg Layered Suite as previously suggested, but represents relic products of the Lebowa Granite Suite or crustal melts into which the Bushveld Igneous Complex intruded into.Item An economic evaluation of the Rosh Pinah polymetallic deposit using the net smelter return model(2018) Shava, Privilege RangariraiItem Primary uranium mineralisation of the central Damara Orogen, Namibia: a petrographic, geochemical and mineralogical account of the granite - hosted uranium deposits situated along the Swakop- and Khan River valleys(2017) Freemantle, Guy GeorgeNamibia, the 6th largest producer of uranium globally, has produced uranium from Pan African granite-hosted (primary) deposits since 1976, and from palaeochannel deposits since 2007; exporting 3 472 tonnes U in 2016. The large granite-hosted deposits at the Husab Mine are expected to add over 5 700 tonnes U/year at peak, while three large primary-hosted deposits remain in various stages of development at Goanikontes, the Ida Dome, and Valencia. This study presents a comprehensive geological, geochemical and uranium mineralogical appraisal of four of the major primary-hosted uranium deposits, all situated within the southern Central Zone (sCZ) of the polydeformational (D1-D3) Damara Belt. The sCZ comprises highly deformed Neoproterozoic sediments, unconformably draped over rheologically competent granite-gneiss domes and inliers of a Palaeoproterozoic basement. A suite of fractionated sheeted leucogranites (SLGs) are a characteristic of the final stages of Orogenic deformation; while most SLGs appear to precede D3 deformation and metamorphism (ca. 510 Ma); most of the mineralised SLGs across the region invade reduced-facies sediments in pressure shadows formed in the hinges and limbs of upright D3 antiforms, proximal to basement inliers. A pre-existing, six-fold, alphabetised SLG classification scheme is revised and extended to categorise distinctive and consistent field and petrographic characteristics of the SLGs across the region. Discriminating SLG sub-types is less consistent in standard geochemical diagrams, except where high field-strength (HFS) and rare-earth elements (REE) are concerned. REE profiles in pre-D3 SLGs reflect abundances, or paucities, of characteristic accessory mineral assemblages; while REE profiles show relative REE enrichment, prominent REEfractionation and -ve Eu anomalies in the uraniferous SLGs, reflecting lower-percentage partial melts in the more uraniferous samples. The overwhelming majority of primary uranium mineralisation is in magmatic uraninite, followed by coffinite which predominate as a replacement phase of uraninite, and more rarely as solid solution with thorite. The refractory minerals betafite and brannerite are rare, but are locally abundant in discrete, magmatic textures within uraniferous SLGs of some deposits. Hydrated uranyl silicates predominate in the supergene portions of the orebodies across the region. An electron microprobe study presents the first comprehensive assessment of uraninite compositions in the region, while Husab deposit betafite and brannerite compositions allow for a well-rounded comparison with refractory minerals from the Rössing deposits. Key Words Primary Uranium, Granite, Orogenic, Damara, Namibia, Rare Earth Elements, Mineralisation, Fractionation, High-grade Metamorphism, Economic Geology, Mining, Processing, Uraninite, Coffinite, Etango, Goanikontes, Husab, Ida Dome, Rössing, ValenciaItem The optimal depletion of mineral deposit(1992) Eshun, Samuel YawsonThe optimal depletion of a mineral deposit involves the optimisation of all the proccesses involved in the mining operation. [Abbreviated Abstract. Open document to view full version]Item Seismological and mineralogical studies of the world’s deepest gold-bearing horizon, the Carbon Leader Reef, West Wits Line goldfields (South Africa): implications for its poor seismic reflective character(2016) Nkosi, Nomqhele ZamaswaziThe measurements of physical rock properties, seismic velocities in particular, associated with ore deposits and their host rocks are crucial in interpreting seismic data collected at the surface for mineral exploration purposes. The understanding of the seismic velocities and densities of rock units can help to improve the understanding of seismic reflections and thus lead to accurate interpretations of the subsurface geology and structures. This study aims to determine the basic acoustic properties and to better understand the nature of the seismic reflectivity of the world’s deepest gold-bearing reef, the Carbon Leader Reef (CLR). This was done by measuring the physical properties (ultrasonic velocities and bulk densities) as well as conducting mineralogical analyses on drill-core samples. Ultrasonic measurements of P- and S-wave velocities were determined at ambient and elevated stresses, up to 65 MPa. The results show that the quartzite samples overlying and underlying the CLR exhibit similar velocities (~ 5028 m/s-5480 m/s and ~ 4777 m/s-5211 m/s, respectively) and bulk densities (~ 2.68 g/cm3 and 2.66 g/cm3). This is due to similar mineralogy and chemical compositions observed within the units. However, the CLR has slightly higher velocity (~ 5070 m/s-5468 m/s) and bulk density (~ 2.78 g/cm3) than the surrounding quartzite units probably due to higher pyrite content in the reef, which increases the velocity. The hangingwall Green Bar shale exhibits higher velocity (5124 m/s-5914 m/s) and density values (~ 2.89 g/cm3-3.15 g/cm3) compared to all the quartzite units (including the CLR), as a result of its finer grain size and higher iron and magnesium content. In the data set it is found that seismic velocities are influence by silica, iron and pyrite content as well as the grain size of the samples, i.e., seismic velocities increase with (1) decreasing silica content, (2) increasing iron and pyrite content and (3) decreasing grain size. Reflection coefficients calculated using the seismic velocities and densities at the boundaries between the CLR and its hangingwall and footwall units range between ~0.02 and 0.05, which is below the suggested minimum of 0.06 required to produce a strong reflection between two lithological units. This suggests that reflection seismic methods might not be able to directly image the CLR as a prominent reflector, as observed from the seismic data. The influence of micro-cracks is observed in the unconfined uniaxial compressive stress tests where two regimes can be identified: (1) From 0 - 25 MPa the P-wave velocities increase with progressive loading, but at different rates in shale and quartzite rocks owing to the presence of micro-cracks and (2) above stresses of ~20 - 25 MPa, the velocity stress relationship becomes constant, possibly indicating total closure of micro-cracks. The second part of the study integrates 3D reflection seismic data, seismic attributes and information from borehole logs and underground mapping to better image and model important fault systems that might have a direct effect on mining in the West Wits Line goldfields. 3D seismic data have delineated first-, second- and third-order scale faults that crosscut key gold-bearing horizons by tens to hundreds of metres. Applying the modified seismic attribute has improved the imaging of the CLR by sharpening the seismic traces. Conventional interpretation of the seismic data shows that faults with throws greater than 25 m can be clearly seen. Faults with throws less than 25 m were identified through volumetric (edge enhancement and ant-tracking seismic attributes) and horizon-based (dip, dip-azimuth and edge detection seismic attributes) seismic attribute analysis. These attributes provided more accurate mapping of the depths, dip and strikes of the key seismic horizon (Roodepoort shale), yielding a better understanding of the relationship between fault activity, methane migration and relative chronology of tectonic events in the goldfield. The strato-structural model derived for the West Wits Line gold mines can be used to guide future mine planning and designs to (1) reduce the risks posed by mining activities and (2) improve the resource evaluation of the goldbearing reefs in the West Wits Line goldfields.