M.Sc. / Please refer to full text to view abstract

Master of Science / Department of Geology / Abdelmoneam Raef / Matthew W. Totten / The Woodford shale in west-central Oklahoma is an organic and silica rich shale that is a prolific resource play producing gas and liquid hydrocarbons (Gupta et al., 2013). Unconventional shale wells are only producible due to modern hydraulic fracturing techniques. Production surveys from unconventional reservoirs show significant variability between wells and even between fracking stages (Kennedy, 2012). The production potential of a particular shale appears to be related to its brittleness and kerogen content "sweetness". Thus, brittleness analysis becomes important when choosing which shales to produce. A rocks brittleness index can be related directly to elastic properties derived from P- and S-wave velocities, as well as, its specific mineral makeup. This project's main focus is to determine the elastic rock properties that affect or relate to Woodford shale brittleness and how they relate to the rock's specific mineral makeup and kerogen content. Measurements to determine elastic properties, based on ultrasonic laboratory testing, were conducted on available Woodford cores. The estimated elastic moduli were evaluated via cross-plotting and correlation with a variety of rock properties. Elastic properties are of essential relevance to forward seismic modeling in order to study seismic response. Mineral makeup, determined via XRD and XRF analyses done by Kale Janssen (2017), was used to calculate a mineral-based brittleness index for comparison with the elastic moduli. Evaluation of the elastic moduli assisted in determining which elastic properties directly relate to the brittleness of the shales and, in turn, to geomechanical aspects. These properties were correlated with data from previous studies including mineral percentages, total organic content (TOC), and thermal maturity. These correlations were used to determine which elastic properties best predict a rock's brittleness index. The calculated brittleness was used to develop a brittleness index map of the Woodford Formation.

No description available.

From introduction: Vein-type mineralization, particularly gold, copper, tin and tungsten has provided a source of metal to man for over 2000 years. These deposits are usually small but in some cases are of very high grade. Prior to 1940 veins were extremely important sources of metals because of their relatively high-grades. However, with improved mining, smelting and concentrating methods, much lower grade material became economic, hence these smaller deposits could no longer hold their dominance. Recently the energy crisis and escalating costs of capital for large projects has made smaller deposits attractive once more (Temblay and Descarreaux, 1978) . At the present time gold, tin and tungsten command high prices on world markets. It is for these reasons that a study of the evaluation techniques pertaining to these deposits has been undertaken. In this review the geological factors which influence the evaluation are stressed. In particular, emphasis is placed on the emplacement of vein deposits, and the subsequent chemical and structural modifications of these deposits. The latter part of the review concentrates on the limitations of the sampling and ore reserve techniques that can be applied to the evaluation of mineralized veins. In the conclusion those techniques that are most applicable are stressed, and an evaluation model is outlined.

Scheelite, wolfram Ite and cassIterIte mIneralizat ion is hosted wIthin numerous quartz-tourmaline-feldspar-fluorite veins at Van Rooi's Vley, N.W. Cape Province . MineralizatIon and hydrothermal alteration within, and around, these veins is hIghly complex and reflects the intricate interaction of hydrotherma l activity upon a structurally deformed sequence of ProterozoIc med ium to high-grade gneisses. Four distinct stages of alteration and mineralization occurred, including a l ate 'epithermal stage'. Although the location of mineralization was strongly controlled by st ructure, the concentration of mineralizati on was controlled by physicochemical variables, of which host-rock geochemistry was particularly important . Further W/Sn mineralization occurs on a local scale, some of which is spatia lly related to minor leucogranite dykes. Leucogranite bodies are not uncommon within the region and some are enriched in Wand Sn. By comparing FIB ra tio s,W/Sn ratios, the alteration mineralogy, the ore mineralogy and the Fe-content of tourmaline, the deposits within the Van Rooi's Vley area can be placed into a 'proximal' to 'distal' classification, with respect to a common source of mineralizing hydrothermal fluids. The Van Rooi's Vley deposit, whilst affiliated to greisen-style deposits, represents a ' distal' quartz-vein lode deposit. / KMBT_363 / Adobe Acrobat 9.53 Paper Capture Plug-in

Pyrrhotite (Fe(1-x)S) is one of the most commonly occurring metal sulfide minerals and is recognised in a variety of types of ore deposits. Since the principal nickel ore mineral, pentlandite, almost ubiquitously occurs with pyrrhotite, the understanding of the behaviour of pyrrhotite during flotation is of fundamental interest. For many nickel processing operations, pyrrhotite is rejected to the tailings in order to control circuit throughput and concentrate grade and thereby reduce excess sulfur dioxide smelter emissions. For the platinum group element processing operations however, pyrrhotite recovery is targeted due to its association with the platinum group elements and minerals. Therefore, the ability to be able to manipulate pyrrhotite flotation performance is of importance. It can be best achieved if the mineralogical characteristics of the pyrrhotite being processed are known and their relationship to flotation performance is understood. Pyrrhotite is known to naturally occur in different forms that have varying physical and chemical attributes. These different pyrrhotite forms are commonly known as magnetic (Fe7S8) and non-magnetic pyrrhotite (Fe9S10, Fe10S11, Fe11S12) and as a result of their varying properties are expected to show some difference in their reactivity towards oxidation and flotation performance. Yet the accounts in the literature are inconsistent as to which of the pyrrhotite types is more reactive. Similarly, there appears to be little agreement in the literature as to which of the pyrrhotite types is more floatable. It is probable that this lack of agreement arises from the fact that previous studies have not given due consideration to the effect of the mineralogy of the samples examined. The success of the discipline of process mineralogy as a whole however, has been to gain an understanding of how the mineralogy of an ore affects its processing properties. The objective of this process mineralogy study was to develop the relationship between pyrrhotite mineralogy and flotation performance based on a thorough characterisation of pyrrhotite from selected nickel and platinum group element ore deposits in terms of their crystallography, mineral association, mineral chemistry and mineral reactivity. This was achieved through the characterisation of the mineralogy and mineral reactivity of pyrrhotite samples obtained from the Sudbury ore in Canada, Phoenix ore in Botswana and the Merensky Reef and Nkomati ores in South Africa. Based on the linkage of these characteristics to flotation performance, an understanding of the relationship and mechanisms that cause pyrrhotite mineralogy to influence pyrrhotite flotation performance has been gained. Mineralogical characterisation of the pyrrhotite samples in this study was performed using ore petrography, x-ray diffraction and mineral chemistry analysis. On the basis of these results pyrrhotite samples were classified as: single phase magnetic 4C Fe7S8 pyrrhotite, single phase non-magnetic 5C Fe9S10 pyrrhotite; two phase magnetic 4C Fe7S8 pyrrhotite intergrown with non-magnetic 5C Fe9S10 pyrrhotite and as two phase non-magnetic 6C Fe11S12 pyrrhotite intergrown with 2C FeS troilite. Nickel was identified as the main trace element impurity in the pyrrhotite structure and the amount of solid solution nickel in the pyrrhotite structure was correlated with whether the pyrrhotite was magnetic or non-magnetic, and whether it coexisted with another pyrrhotite phase. All pyrrhotite samples investigated showed a strong association to pentlandite that occurred in both granular and flame pentlandite forms. These key features of pyrrhotite mineralogy were in turn shown to be controlled by the bulk composition and cooling history of the monosulfide solid solution (MSS) from which pyrrhotite is derived. The reactivity of the different pyrrhotite samples towards oxidation was determined using open circuit potential, cyclic voltammetry and oxygen uptake measurements at both pH 7 and 10. Non-magnetic Sudbury Copper Cliff North pyrrhotite was the most unreactive of the samples examined, whereas magnetic Sudbury Gertrude West pyrrhotite was the most reactive. The magnetic Sudbury Gertrude West pyrrhotite was so reactive that open circuit potential and oxygen uptake measurements showed it was already passivated and likely covered with hydrophilic ferric hydroxides. The magnetic Phoenix pyrrhotite was slightly less reactive than the magnetic Sudbury Gertrude West pyrrhotite. The reactivity of the Nkomati Massive Sulfide Body (MSB) mixed pyrrhotite was in between that of the non-magnetic Sudbury Copper Cliff North and magnetic Phoenix pyrrhotite, due to the combined contribution of intergrown magnetic and non-magnetic pyrrhotite to its reactivity. The flotation performance of the different pyrrhotite samples was investigated at both pH 7 and 10 using microflotation tests. A variety of different reagent conditions was also investigated that included the use of different chain length xanthate collectors (sodium isobutyl xanthate (SIBX), sodium normal propyl xanthate (SNPX)) and the use of copper activation. The collectorless flotation of the non-magnetic Sudbury Copper Cliff North pyrrhotite was the greatest of the samples investigated. Only with the addition of flotation reagents were differences in the floatability of the other pyrrhotite samples identified. Magnetic Phoenix pyrrhotite showed good flotation performance whereas the flotation performance of the magnetic Sudbury Gertrude and Gertrude West pyrrhotite was very poor. The Nkomati MSB mixed pyrrhotite only showed good flotation performance at pH 7. All pyrrhotite samples generally showed improved flotation performance with the use of the longer chain length SIBX collector than the shorter chain length SNPX, whereas the efficiency of copper activation was influenced by pyrrhotite mineralogy, pH and collector chain length. Differences in the flotation performance of the pyrrhotite samples investigated were linked to their reactivity towards oxidation. Although not directly measured, the formation of hydrophilic ferric hydroxides on pyrrhotite surfaces due to oxidation was inferred as the reason for the poor flotation performance of some of the pyrrhotite samples. Key features interpreted to influence both pyrrhotite reactivity and flotation performance were pyrrhotite crystallography, mineral chemistry and mineral association. It has been proposed that differences in the amount of vacancies in the pyrrhotite crystal structure influence the oxidation rate and similarly the greater proportion of ferric iron in the magnetic pyrrhotite structure was argued to account for its greater reactivity relative to non-magnetic pyrrhotite. Differences in the solid solution nickel content and trace oxygen in the pyrrhotite structure were also proposed as additional characteristics influencing pyrrhotite oxidation rate and flotation performance. Depending on the degree of association of pyrrhotite to pentlandite, its flotation performance could be affected by the liberation characteristics and flotation of composite particles containing abundant locked flame pentlandite, although this could be manipulated by changing the grind size. The presence of nickel ions derived from the flame pentlandite in these composite particles could also assist in the activation of pyrrhotite and further improvement of its flotation performance. Some guidelines are also presented as to which simple mineralogical and mineral reactivity measurements have been of the most use in developing the relationship between mineralogy and flotation performance. / Thesis (DPhil)--University of Pretoria, 2009. / Materials Science and Metallurgical Engineering / unrestricted

The P2 reverse fault in the metasedimentary basement rocks of the eastern Athabasca Basin is the main structural control of the world-class McArthur River uranium deposit. The earliest preserved assemblage along the fault is oxy-dravite, rutile, quartz, pyrite and graphite. This assemblage formed at temperatures of up to 890 °C, during regional metamorphism or a thermal event at ~1.75 Ga. The exhumation and surface exposure of the rocks was accompanied by paleo-weathering, and the deposition of the Athabasca sandstones. Diagenetic fluids of the sandstones altered the basement rocks to form Sr-Ca-SO42- rich aluminum phosphate sulfate (APS) minerals + hematite ± kaolin. The onset of hydrothermal activity along the basement and the P2 fault is recorded by local anatase at 1569 ± 31 Ma. Uraniferous fluid formed an assemblage of sudoite illite, magnesio-foitite and LREE+P rich APS minerals (rims earlier diagenetic-type APS minerals) along the entire P2 fault. Magnesio-foitite exhibits a high X-site vacancy (0.70 – 0.85 apfu) and contains high Al in its Y-site (0.70 – 1.12 apfu), suggesting that magnesio-foitite likely replaced kaolin. The REE pattern of magnesio-foitite is similar to that of uraninite (CeN<YN), likely due to their co-crystallization with LREE-rich APS minerals. APS minerals show variably high S/P ratios (0.05 - 0.21) in proximity to the deposit and low ratios (0.11 - 0.13) far from the deposit along the P2 fault, indicating reducing conditions in the ore zone. Low values of δD (-41 to -98 ‰) and high values of δ11B (+13.1 to +23.2 ‰) for magnesio-foitite suggest that groundwater interacted with carbonates or evaporites and was progressively enriched in 11B through interaction with illite and kaolin minerals. This work demonstrates that i) the P2 fault was a site of extensive fluid-rock interaction, ii) mineralizing fluids travelled along the entire P2 fault in the basement, iii) the deposition of the McArthur River deposit was controlled by the availability of a reducing fluid through the P2 fault, and iv) mineral chemistry (tourmaline and APS minerals) may help identify fertile faults in exploration for uranium deposits.

>Magister Scientiae - MSc / The present research deals with the characterization of the Lower Ecca Group in terms of sedimentology, mineralogy and organic geochemistry. A field study was conducted in order to characterize the sedimentology and thereby determine the environments of deposition of the Prince Albert, Whitehill and Collingham Formations. In addition, shale samples were subjected to geochemical and mineralogical analyses so as to ascertain its source rock properties. The study utilized X-ray diffraction (XRD), scanning electron microscopy with an energy dispersive spectrometer (SEM-EDS), total organic carbon (TOC) and Rock-Eval pyrolysis to determine the mineralogy and organic geochemistry of shale from the formations under investigation. The sedimentological investigation revealed that the upper Prince Albert Formation is dominated by shale with thin beds of carbonate. These shales are interpreted to have been deposited by suspension settling in a marine environment which was occasionally interrupted by deposition of carbonates that form in a shallow marine environment. The overlying Whitehill Formation consists predominantly of carbonaceous shale with relatively more resistant shale beds also present. The fine sediments are interpreted to have been deposited from suspension settling under anoxic bottom conditions which would favor the preservation of organic rich material. Deposition of the Whitehill Formation was followed by the Collingham Formation which is dominated by rhythmic deposits of shale and sandstone that are occasionally interrupted by tuff layers. The clay size sediments are interpreted to have been deposited from suspension settling which are interbedded with low density turbidite current deposits in a marine environment. Based on the findings of the field study, it is apparent that the Prince Albert and Collingham Formations were deposited in marine environments, with the Whitehill Formation being deposited in an anoxic environment. These environments are known to be dominated by phytoplanktonic organisms and algal debris, and as such shales deposited in these environments contain predominantly Type I (derived from algae) and II kerogen (derived from plankton). It can therefore be postulated that Type I and II kerogens are the dominant constituents of organic matter in the Lower Ecca Group shales. Mineralogically, the shales consist chiefly of kaolinite, smectite and illite clay minerals, which are derived from a combination of weathering of feldspars, and the alteration of other clay minerals. The latter being inferred from the existence of albite in all the studied shale samples, pyroclastic material observed in the field, as well as the occurrence of alteration along clay mineral edges.

Philosophiae Doctor - PhD / Coal fly ash has been studied extensively to understand the environmental impacts associated with its disposal, management and reuse. Although several beneficiation processes have been proposed, there has been little or no emphasis on the environmental safety of such processes, products and wastes. Elemental analysis has revealed that toxic elements and radionuclides are present in coal fly ash. Rare earth elements (REE) such as La, Ce and Y are also present in significant amounts in coal fly ash. The aims of this study were to determine the total elemental composition of coal fly ash using different analytical techniques; to validate the application potentials of fly ash beneficiation processes in terms of their environmental safety; and to valorise coal fly ash with a view of recovering REE either by concentrating or leaching the REE in the coal fly ash, products or waste from the beneficiation processes. The beneficiation processes studied were treatment of acid mine drainage (AMD) with fly ash; and the synthesis of geopolymer from fly ash. The fresh fly ash sample used in this study was collected directly from the hoppers at Matla power station and the AMD sample was collected from Carletonville goldmine. A total of 54 major, trace and REE were accurately determined in the ash using different analytical techniques. It was shown that the elemental content of Matla fly ash was of the same order as the SRM NIST coal fly ash 1633b. The comparative study of the four analytical techniques established that ENAA can accurately determine the major, minor and trace elements; that XRF is best suited for the determination of the major and minor elements, whilst the LA ICP-MS is reliable for trace elements determination. The solid residue (AMD/FA) resulting from the AMD interaction with fly ash was characterized with fly ash and the results compared. The results revealed that the amounts of La (141.09 ± 3.85 mg/kg), Ce (27.45 ± 2.04 mg/kg), and Nd (63.73 ± 0.05 mg/kg) in AMD/FA residue was considerably higher than their average abundance in the earth crust that varies from 66 mg/kg in Ce and 40 mg/kg in Nd to 35 mg/kg in La. The results also showed that the AMD/FA residue contained As (11.39 ± 1.21 mg/kg), Cd (3.77 ± 0.02 mg/kg), Cr (72.43 ± 1.27 mg/kg), Hg (10.50 ± 0.85 mg/kg), Ni (124.15 ± 1.6 mg/kg) and Pb (22.46 ± 1.43 mg/kg) which are potentially harmful if leached in to the environment in excessive amounts.

Les études géologiques des régions volcaniques de Mars ont clairement montré la diversité et la complexité du volcanisme martien avec des structures aux morphologies variées, témoins de son évolution volcanique et magmatique. Une meilleure compréhension de ce volcanisme nécessite toutefois une connaissance plus précise de la composition minéralogique de ces régions. Cette composition est en effet très dépendante des conditions internes de la planète et de son évolution. Dans ce travail de thèse je me suis donc intéressée à l’évolution volcanique et interne de Mars à partir d’une étude de la minéralogie obtenue grâce à l’imageur hyperspectral OMEGA/Mars Express. Le jeu de données OMEGA a permis la cartographie à l’échelle globale et avec une résolution kilométrique des principaux minéraux mafiques (pyroxènes et olivines), et des phases ferriques, incluant les oxydes ferriques nanophases, qui permettent de jauger l’état d’oxydation de la surface et de tracer la présence de poussière. Leurs distributions spatiales confirment la composition basaltique des terrains de l’hémisphère sud et de certaines régions sombres des plaines du nord ainsi que la nature nanophasée des oxydes ferriques présents dans la poussière martienne. Ces cartes représentent des produits complets et finaux qui sont mis à la disposition de la communauté. En complément de cette analyse globale, la distribution de l’olivine à la surface de Mars a fait l’objet d’une étude locale plus détaillée mettant en évidence plusieurs aspects du volcanisme et du magmatisme martien. Des laves hespériennes enrichies en olivine ayant rempli des dizaines de cratères et de dépressions de l’hémisphère sud ont été identifiées. De l’olivine a également été identifiée dans les plaines du nord associée à du matériau excavé par des cratères (<20 km) et à des affleurements étendus suggérant que ces plaines du nord soient également en partie recouvertes de ces laves. Ces observations peuvent s’expliquer par un évènement planétaire de volcanisme fissural durant le début de l’Hespérien. Ceci indique également que la couche supérieure de sédiment présente dans les plaines du nord est peu épaisse et d’origine volcanique. Cet enrichissement en olivine des laves hespériennes, à l’opposé des terrains noachiens dépourvus de signatures, pose la question d’une évolution des conditions internes de la planète entre ces deux périodes, et/ou d’une altération importante des terrains noachiens. De l’olivine associée à des éjectas de grands cratères (>20 km) dans les plaines du nord, ainsi qu’à des buttes dans l’hémisphère sud suggère que la croûte noachienne/primitive enfouie soit enrichie en olivine au moins en certains endroits. Enfin, de l’olivine associée à des buttes sur les terrasses des bassins d’Argyre et d’Hellas, interprétées comme étant des éjectas de manteau, indique que le manteau martien a subi un overturn à la suite de sa cristallisation. La dernière étape de mon travail a consisté à identifier les régions sources de certaines météorites martiennes en recherchant la similarité de leurs signatures spectrales dans l’infrarouge proche avec celle de la surface de Mars. Un des résultats majeurs de cette étude est que les shergottites basaltiques Los Angeles et Shergotty ont des signatures spectrales similaires à celles des grands massifs volcaniques hespériens tels que Syrtis Major, Thaumasia et Hespéria Planum. Une telle analogie est en accord avec un âge ancien pour ces météorites. / Geologic studies of martian volcanic regions have demonstrated the diversity and complexity of the martian volcanism through various morphologies, witnesses of the volcanic and magmatic evolution of this planet. A better understanding of this volcanism nevertheless requires a better knowledge of the mineralogical composition of these regions. This composition highly depends on the internal conditions of the planet and its evolution. In my PhD thesis, I focused on the internal and volcanic evolutions of Mars from a study of the mineralogy obtained with the visible near-infrared imaging spectrometer OMEGA / Mars Express. The OMEGA dataset has allowed the mapping of key anhydrous mineral of the martian surface at a global scale with a kilometer spatial resolution. These minerals are major mafic minerals (pyroxene and olivine), and ferric phases, including nanophase ferric oxides. Their spatial distributions confirm the basaltic composition of the southern hemisphere and the low albedo regions of the northern plains, as well as the nanophase nature of ferric oxides present in the martian dust. These global maps represent complete and final products and are available for the community. In addition to this global analysis, the global distribution of olivine on the surface of Mars was the subject of a more detailed local study highlighting several aspects of the martian volcanism and magmatism. Hesperian olivine enriched lavas that have filled dozens of craters and depressions in the southern hemisphere were identified. Olivine was also identified in the northern plains associated with material excavated by craters (<20 km) and with extended outcrops, suggesting that the northern plains were also partly filled with these lavas. These observations can be explained by a planetary event of olivine enriched fissural volcanism during the early Hesperian. They also indicate that the upper layer of sediment present in the northern plains is very fine (<100m) and of volcanic origin. This olivine enrichment of hesperian lavas, unlike olivine-depleted noachian terrains, questions the variation of internal conditions of the planet between these two periods, and/or significant alteration of the noachian terrains. Olivine associated with large crater ejectas (> 20 km) in the northern plains, and buttes in the southern hemisphere suggests that the buried noachian/primitive crust was olivine enriched in some locations. Finally, olivine found in buttes on terraces of Argyre and Hellas basins, interpreted as mantle ejectas, indicates that the martian mantle have experienced an overturn after its crystallization. The last chapter of my work was to identify the source regions of Martian meteorites by looking for some similarity in their spectral signatures in the near infrared with those of the martian surface. A major outcome of this study is that the basaltic shergottites Shergotty and Los Angeles have spectral signatures similar to those of the hesperian volcanic massifs such as Syrtis Major, Hesperia Planum and Thaumasia Planum. Such an analogy is consistent with an old age for these meteorites.