Ce mémoire décrit les corps dolomitiques des zones de Ranero et El Moro (vallée de la Karantza, zone Cantabrique, NO de l’Espagne) et précise les variations temporelles et latérales de leurs attributs pétrographiques et géochimiques. Les corps dolomitiques sont portés par les calcaires Albiens, déposés sur la marge du bassin Basque-Cantabrique en période d’intense subsidence. Les dolomies sont formées par replacement et par cémentation, et précédées et suivies par divers types de ciment calcitique. L’étude pétrographique, minéralogique et géochimique (XRD, ICP, XRF, isotopes stables et Sr) est conduite le long de sections transverses sur les corps dolomitiques et permet de comparer les caractéristiques de plusieurs stades de circulations hydrothermales. Deux épisodes contrastés de dolomitisation sont identifiés. Les dolomies précoces sont ferreuses, très localement associées à une minéralisation de type MVT, appauvries en δ18O (de -14 à -10‰ V-PDB) et remplacent largement les calcaires massifs en générant des zebras. Les dolomies tardives sont non-ferreuses, plus sévèrement appauvries en δ18O (-19 to -15‰ V-PDB), et ne semblent pas remplacer le calcaire mais, au contraire, les dolomies précoces. Toutes ces dolomies sont pratiquement stœchiométriques (49.76 à 51.59 mole% CaCO3). Leurs inclusions fluides ont piégé des saumures de haute température (Th de 120 à 200°C). Leur contenu en Sr, radiogénique, suggère que les fluides responsables de la dolomitisation ont préalablement circulé à travers des roches silicoclastiques. La texture comme les propriétés pétrophysiques des dolomies sont largement affectées par les déformations cataclastiques et un épisode tardif de dédolomitisation (météorique).Le premier épisode de dolomitisation résulte probablement de l’expulsion des fluides issus de la compaction du bassin adjacent et de leur migration le long des fractures affectant la marge de la plateforme carbonatée Albienne. Ces fluides précoces étaient riches en Mg, Fe et peut-être légèrement acides pour pouvoir remplacer les calcaires. Les fluides responsables du deuxième épisode de dolomitisation sont pauvres en Fe, paraissent plus chauds et en relation avec une anomalie thermique. / This study documents the temporal and lateral variation in petrographic and geochemical signatures of fault-related dolomite bodies in the Ranero and El-Moro areas (Karrantza valley, Cantabrian mountains; NW Spain). These dolomite bodies are hosted in Albian carbonates, which were deposited at the margin of the Basque-Cantabrian Basin during an intense rift-related subsidence. Fluid circulations generated replacive and cementing dolomites, paragenetically predated and followed by various calcite cements. Petrography, mineralogical and geochemical systematics (XRD, ICP, XRF, stable and Sr isotopes) along sections cutting the dolostone bodies document successive hydrothermal stages. Two contrasting dolomite formation events are evidenced. Early dolomites are ferroan, locally associated with MVT mineralisation, δ18O depleted (-14 to -10‰ V-PDB) and mostly replace limestone producing abundant zebra lithotypes. Later dolomites are non-ferroan, severely δ18O depleted (-19 to -15‰ V-PDB), and do not replace limestones but rather previous dolomites. Dolomites are generally stoichiometric (49.76 to 51.59 M% CaCO3). Fluid inclusions record high temperature brines (Th 120 to 200°C). Sr isotope data suggest that the dolomitising fluids interacted upstream with siliciclastic lithologies. The dolomite fabric and its petrophysical properties are variably altered through cataclastic deformation and late (meteoric) dedolomitisation.The first episode of pervasive ferroan dolomitisation probably resulted from compactional dewatering of basinal fluids from the nearby Basque trough and hydrodynamic fluid flow along the fractures in the Albian carbonate platform. These early fluids must have been Mg, Fe-rich and slightly acidic (limestone-replacive). The second episode of very hot and localized dolomitisation may be related to a thermal anomaly and/or convective flow of Fe-poor fluids.

Orientador: Arai Augusta Bernardez Pecora / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-11T13:29:17Z (GMT). No. of bitstreams: 1 Hory_RogerioIshikawa_D.pdf: 3549862 bytes, checksum: 727c6ab5dce7454b6af9546842232b2e (MD5) Previous issue date: 2007 / Resumo: Este trabalho apresenta o estudo experimental do processo de combustão de carvão mineral brasileiro em reator de Leito Fluidizado Circulante (LFC) com o objetivo de avaliar as taxas de emissões de di óxido de enxofre (S02) e eficiência de conversão de carbono no processo de combustão. Para diminuir a emissão do S02 nos gases de exaustão, foi adicionado, ao carvão, quantidades de calcário dolomítico (dolomita), de modo que a relação molar entre o cálcio (Ca) presente no calcário e o enxofre (S) presente no carvão variou entre 0,0 e 2,0. A variação na relação molar Ca/S, como é denominada na literatura, foi um dos dois fatores avaliados neste trabalho. O outro fator envolvido nos testes foi o excesso de ar utilizado para combustão do carvão. Trabalhou-se com excesso de ar na faixa de 20 a 30%. Foram realizados 11 ensaios seguindo um planejamento experimental estatístico do tipo CCD (Composite Central Design) e mais 02 ensaios complementares. A relação molar Ca/S de 0,6 apresentou emissão zero de S02 e propôs-se utilizar uma nova relação molar: (Ca+Mg)/S para retratar processos de sorção com dolomitas. Para emissão zero de S02, uma relação molar (Ca+Mg)/S de 1,8 já é suficiente. Foram obtidas eficiências de conversão do carbono entre 86,0 e 93,0% para combustão do carvão / Abstract: This work presents an experimental study with Brazilian mineral coal combustion in a Circulating Fluidized Bed (CFB) reactor with the objective to evaluate the sulphur dioxide emissions (S02) and the carbon conversion efficiency in the combustion processo Dolomite was added to the coal to minimize the S02 emissions during combustion. The quantity of dolomite added was calculated based on the molar relation of calcium (Ca) present in the dolomite and sulphur (S) present in the coal. Ca/S molar relation had a variation between 0,0 and 2,0. Two factors were evaluated in this work: Ca/S relation and excess of air during combustion which had a variation between 20 and 30%. Eleven (11) experimental tests were evaluated following a statistical experimental design called CCD (Composite Central Design) and 02 (two) more complementary tests. Emissions of S02 with zero value were obtained for a Ca/S of 0,6. It was also proposed in this work a new relation for sorption of S02 with dolomite: (Ca+Mg)/S relation. Tests showed that a relation of 1.8 for (Ca+Mg)/S is sufficient for zero emissions of S02. Carbon conversion efficiency between 86.0 and 93.0 was also obtained during coal combustion / Doutorado / Termica e Fluidos / Mestre em Engenharia Mecânica

M.Tech. (Extraction Metallurgy) / The discovery of gold at Langlaagte in 1886 led to the development of gold mining in the Far West Rand in 1934. When shafts were sunk, water from the dolomites posed a serious threat to mining. Despite cementation that sealed the many fissures, water still found its way into the underground workings. This led to the “uniform” policy of dewatering. The farming communities in the area that were dependent on the ground water had to be considered, as they had lost their livelihood. As the water levels lowered, dolines and sinkholes were formed, posing a serious threat to life and property. When the mines eventually cease to operate, be it due to high working costs, or the declining grade of the ore body, the re-watering of the dolomitic compartments will occur as a natural consequence. When water comes to within six metres of the original water level, ground instability, the formation of dolines and sinkholes, both new and existing, will occur, threatening the important rail link between Pretoria and Cape Town as it passes through Far West Rand, as well as the N12 between Johannesburg and Potchefstroom, as well as the N14 which lies to the east connecting the Gauteng Province and the North West Province. The dewatering of the compartments caused the soil which formed the roof of the cavities to dry. Re-watering will cause this dry, stable material to become wet and unstable. Where mixtures of slime and/or other material, which is not part of the geological composition of that area was used, the same phenomenon will apply. A further complication is caused by the slimes dams which are unlined. In fact, some of the slime dams were deliberately constructed over cavernous dolomite. This large mass of mine tailings over the dolomitic aquifers will “liquefy”. If the re-watering is not carefully managed the rising water table will undoubtedly trigger a rash of new sinkholes, with catastrophic consequences for unsuspecting communities that may have been established in sensitive areas. The results of previous investigations by the Departments Minerals, Energy and Water Affairs who, due to the loss of institutional memory, might not be able to find the relevant information. Other organizations such as the Council for Geoscience could be using the results for consultancy. The information should be digitized and be available to the broader South African public. FWRDWA is currently in charge of monitoring events in the area. Levelling observations have been carried out quarterly and, so far the movement of ground is minimal. The potential hazard of ground instability will recur with the re-watering of the dolomitic compartments of the Far West Rand. To support what could happen, reference is made to events which took place in the late seventies when the Far West Rand had an above average rainfall. The Donaldson Dam overflowed into the Wonderfontein Spruit and into the dewatered Venterspost compartment. As a result, the water level of the Venterspost Compartment rose rapidly which led to the re-activation of sinkholes and the formation of new ones in the Venterspost area. In the present work levelling has been carried out along most of the loops affected and the results of the levelling give an impression that the surface is currently relatively stable. This Dissertation is presented as an attempt to alert the authorities to the potential dangers if the post mining period is not carefully monitored and insufficient provision made to deal with potential contingencies.

Carbonatites are unique and enigmatic magmatic rocks of unclear origin, with very specific mineralogy and geochemical properties. They are predominantly composed of magmatic calcite or other carbonate minerals (Le Bas 1987) and have low content of SiO2 (Le Maitre 2002). Origin of these peculiar magmas is still not clear but they appear to represent an important "window" into processes in Earth's mantle. They are considered either as residual melts from a fractionated carbonated nephelinite or melilitite (Gittins 1989; Gittins and Jago 1998), as immiscible fractions of CO2-saturated silicate melts (Freestone and Hamilton 1980; Amundsen 1987; Kjarsgaard and Hamilton 1988, 1989; Brooker and Hamilton 1990; Kjarsgaard and Peterson 1991; Church and Jones 1995; Lee and Wyllie 1997; Dawson 1998; Halama et al. 2005; Brooker and Kjarsgaard 2011), or as primary melts which are were generated from CO2-bearing peridotite through partial melting (Wallace and Green 1988; Sweeney 1994; Harmer and Gittins 1998; Harmer et al. 1998; Ying et al. 2004). Abundances of rare earth elements (REE) are often high in carbonatites because carbonatitic magmas can dissolve these elements much easily than silicate magmas (Nelson et al. 1988). Carbonatitic magma can also dissolve large quantities of Sr, Ba, P and mainly Zr and Nb,...

The subject of this diploma thesis is to analyse the Dolkam Šuja Company, a.s. Through the selected methods, described in the first part, the company’s current situation is evaluated and on its basis the measures for improving the current state of the company are proposed.

Masters of Science / This study was conducted to investigate hydrogeochemical processes controlling the evolution of groundwater chemistry and their influence on water quality in the Heuningnes Catchment. The role or influence of hydrogeochemical processes in groundwater quality in aquifer systems remains poorly understood. One of the ways of improving such understanding is to employ different techniques to explore key processes that govern groundwater quality in aquifer systems. Therefore, the present study investigated hydrogeochemical processes of groundwater resources and identified key processes that explained its quality from a spatiotemporal perspective. The quantitative approach that provides the ability to assess relationships between variables both spatially and temporally was applied. Groundwater sampling was done on four occasions during July 2017, October 2017, March 2018, and July 2018. Identification of hydrogeochemical processes controlling the evolution of groundwater chemistry and quality was done using various complementary tools. These tools included classification of the main water types, evaluation of water-rock interaction by means of stoichiometry analysis and bivariate correlation plots, inverse geochemical modelling, and statistical analysis (hierarchical cluster analysis and factor analysis). Physical parameters were measured in situ, while water samples were collected from boreholes, piezometers, springs, and artesian boreholes for laboratory analysis for major ions analysis. Descriptive and bivariate statistical methods were used to summarise and evaluate the strength of the relationship between variables, while multivariate statistical methods were applied to group similar samples based on their chemical compositions. Tri linear Piper diagrams were generated to characterize water type based on double normalizing the proportions of cations and anions, while correlation and stoichiometric analysis were applied to identify hydrogeochemical processes influencing groundwater chemistry. The results generated from the trilinear Piper diagrams confirmed the dominance of sodium and chloride ions in waters of the Heuningnes Catchment. Groundwater of a Na/Cl type is typical for a coastal aquifer characterised by saline, deep ancient groundwater. The lower parts of the Catchment were characterised by saline groundwater. The results indicated that shallow groundwater samples within the study area were more mineralised as compared to deep groundwater with EC values ranging between 20.8 and 2990 mS/m, with waters within the Table Mountain Group region (TMG), recording the lowest values. Deep groundwater for boreholes and artesian boreholes located upstream in the Catchment was fresh and yielded some of the lowest EC values recorded with an EC value below 50 mS/m. Generally, EC values increased from the upper TMG region of the Catchment towards the Bokkeveld shale region downstream and were highest during the dry season of 2018. The results indicated strong geological influences on water chemistry. Bivariate correlation and stoichiometric analysis identified cation exchange, adsorption, evaporation, weathering of carbonates, sulphates and silicate minerals as processes influencing the chemistry of groundwater in the Heuningnes Catchment. The Saturation Index (SI) results showed a change of calcite, dolomite, aragonite, gypsum, anhydrite, halite, melantinterite, siderite and sylvite from being undersaturated to oversaturated at some areas for the different seasons along the flow path. The mass-balance modelling results indicated that ion exchange and reverse ion exchange processes were more dominant at low elevations along the same flow path during the dry periods. However, at high elevations along the flow path, silicate weathering was the dominant process taking place. The findings of this study demonstrated the influence of hydrogeochemical processes in changing the water chemistry along the flow paths. In conclusion, the study showed the value of utilising various assessment tools as complementary techniques to improve the understanding about hydrogeochemical processes, and its influence on evolution of groundwater chemistry and quality. Based on the findings of the study the following recommendations were made for future studies; the sample points or sample boreholes in the study Catchment should be increased; and to have more sampling trips to enable better comparison between the possible processes

Premise of the Study: There is growing interest in understanding plant–plant interactions via pollen transfer at the community level. Studies on the structure and spatial variability of pollen transfer networks have been valuable to this understanding. However, there is high variability in the intensity of sampling used to characterize pollen transfer interactions, which could influence network structure. To date, there is no knowledge of how sampling effort influences the richness of pollen on stigmas and thereby transfer interactions observed, nor how this may vary across species and study sites. Methods: We use rarefaction curves on 16 species to characterize the relationship between sampling effort (number of stigmas analyzed) and the richness of pollen transfer interactions recorded. We further assess variability in this relationship among species, plant community types, and sites within a single plant community. Key Results: We show high among-species variation in the amount of sampling required to sufficiently characterize interspecific pollen transfer. We further reveal variability in the sampling effort-interaction richness relationship among different plant communities and even for the same species growing in different sites. Conclusions: The wide heterogeneity in the sampling effort required to accurately characterize pollen transfer interactions observed has the potential to influence the characterization of pollen transfer dynamics. Thus, sampling completeness should be considered in future studies to avoid overestimation of modularity and specialization in pollen transfer networks that may bias the predicted causes and expected consequences of such processes for plant–plant interactions.

Disertation thesis deals with development of hot dolomite filter for the purposes of cleaning of gas polluted by biomass and waste gasification with ash and tar as well as sulphur and chlorine compounds as main pollutants. Gas is then cleaned so that it can be utilized in cogeneration units with combustion engines. This supports advancement of gasification techniques using decentralized power and heat generation especially for design of small scale units. Concrete aims of this thesis are stated in chapter 2. Experimental fluid gasification stend Biofluid 100 has been in operations at Brno University of Technology (BUT) since 2000 and it helps research of biomass and waste gasification. Development of the filter initially utilized needs and experience with the utility during cooperation of BUT and ATEKO Hradec Králové. Water scrubber was used for gas cleaning, however, this method proved to be ineffective. Alternative solutions were considered. Based on literature search, natural catalysts with limestone basis were opted. First part of the thesis presents literature search of this issue. Historic development and description of gasification process are briefly discussed as well as elementary classification of gasification generators. This part is followed by chapters dealing with gas pollutants. Tar – the most significant pollutant – is discussed in a separate chapter which presents tar formation, its classification, characteristics and methods for its removal. Brief summary of requirements on gas properties with respect to its utilization in various applications (especially in cogeneration units) follows. Other part of the literature search part focuses on methods of removal of tar from gas, especially on catalyst methods. Dolomite characteristics, description of dolomite calcination as well as simplified kinetic model of tar cracking using dolomite are presented. Based on literature search, laboratory and verification equipment was designed for the purposes of dolomite properties testing. Equipment description as well as description of experimental stend Biofluid 100 where the experimental tests were carried out can be found in introduction of the experimental part. This is followed by a complete description of pilot equipment design of hot dolomite filter with general description of experimental work process, brief characteristics of the fuel and catalytic material used. Final part of the work comprises of experiment results that were carried out on the pilot equipment. Focus is on efficiency of tar removal in connection with operation temperature, amount of catalytist and material used. Influence of these parameters on gas composition and energy intensity of the whole process under these conditions is mentioned as well. Possibility of autonomous unit operations without electricity heating is briefly outlined. Summary of the most significant results including the potential of future hot dolomite filter development is stated the final part of the thesis.

Thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, 2016 / Keywords/key concepts: Dolomite, Dolomitic ground, Disaster Risk Management, Physical Vulnerability, Low-income settlements, Housing Policy, Services delivery, Responsibility, Living with risk, Human Behaviour, Basic Human Rights Ground underlain by dolomite may be hazardous to development due to the potential occurrence of subsidence and sinkholes. These potentially disastrous occurrences are in many instances caused by human interaction with the soil through the ponding of water or leaking of wet infrastructure such as water and sanitation services. Construction materials and techniques, as well as effective maintenance of waterborne services have traditionally been acknowledged as having a significant bearing on the level of risk that communities face when living on such potentially dangerous land. The spatial distribution of settlements on dolomite in the Gauteng City Region (GCR) is already widespread and expected to increase as urbanisation intensifies. Similarly, the challenge of considering the physical vulnerability of low-income settlements is expected to intensify. Welldefined procedures and guidelines govern the development of human settlements on dolomitic ground. However, the classification and characterisation of low-income and informal settlements are not as advanced as that of formal residential developments. In addition, the guidelines regarding management of settlements on dolomite focus significantly on geotechnical interventions, leaving a gap in the influence that human behaviour can play in possible disaster risk reduction on such ground. The thesis considers the significance of different low-income settlement types on dolomite, relative to perceived human behaviour in association with principles of disaster risk reduction. It hypothesizes that an understanding of settlement type in relation to human behaviour and a stronger emphasis on monitoring via official channels could address some of the conflicts in the development-on-dolomite debate and thereby reduces settlement vulnerability. The research methods included quantitative and qualitative components, commencing with a literature review that spanned multiple disciplines and sectors. Fieldwork included spatial investigation and consideration of low-income settlement types with regard to, for example building material use, dwelling size and dwelling layout, and wet services infrastructure provision and location. The thesis subsequently identify and explore low-income settlement types in the study area. The research explores a number of sample settlements to consider the physical vulnerability and potential key areas of intervention and risk reduction, outside of the traditional geotechnical arena. The evaluation then applies the Analytical Hierarchy Process (AHP), a form of Multi Criteria Analysis (MCA), to identify important variables and indicators related to human behaviour and the physical vulnerability of settlements on dolomite that can be harnessed to intervene in the debate, and possible improve the safety of communities living with this risk. Although not affecting the research outcome directly, a specific observation during the course of engagement with specialists across disciplines was that experts in even closely related practice areas view low-income settlement development and upgrading on dolomite differently. The differences in viewpoints result in contradictions in approaches between housing officials, disaster managers, socio-environmental practitioners, engineers and geologists. Even small differences in approach have been shown to have significant effects on the practicalities surrounding decision making related to low-income settlements and especially informal settlement relocation or upgrading. The outcome is a set of prioritised indicators that could enable specialists, officials and the public to consider different elements of low-income settlements based on its physical vulnerability. By focussing on the indicators most likely to result in reduced vulnerability, actions that drive settlement development, upgrade and resettlement could be prioritised. Interestingly, one of the findings of the research is that it is not so much the settlement type based on informality that makes a difference in the exposure to risk – physical vulnerability is deemed to be significantly affected by official (municipal-sphere) actions, monitoring and awareness. Finally, the research enables the integration of technical knowledge with behavioural considerations when living on dolomite, thus highlighting opportunities to bring technical and non-technically skilled stakeholders in the debate closer together. / MT2017

Water is an essential element for life and crucial to survival. South Africa is a semi-arid country and therefore water should be protected and managed effectively by all residents of the country. In the 1830s the Mooi River was the key reason for the Voortrekkers to establish Potchefstroom at a locality adjacent to this river. The Voortrekkers noticed the dolomitic outcroppings in the vicinity, but still opted to reside next to the river for it provided easily accessible water and fertile soil. Since the 1830s water legislation regulating the management and use of the water in the Mooi River has been amended innumerable times to bring us to the current situation of Potchefstroom’s water (mis)management by the role-players and stakeholders of the water source. As a resident of Potchefstroom, the researcher has a keen interest in the origin of the city’s water sources, the re-routing of the water from the origin to the water purification unit via the open-on-top cement canal system, and the overall management of these canals and their servitudes. In order to conduct a research study on the Mooi River’s water re-routing canals and servitudes, the following research methods were applied: The researcher performed a comprehensive literature review, conducted fieldwork, held interviews with landowners and experts in the geographical area of the Mooi River Valley, and performed statistical analyses as well as content analyses of the findings. Some of the most alarming findings include the lack of co-operative governance between water users and – authorities, and the current public management and disaster risk management challenges in the re-routing of water from Klerkskraal Dam down to the water purification plant of Potchefstroom. It is recommended that the major stakeholders of the Mooi River Valley, e.g. the disaster management centre in Potchefstroom, the Department of Water and Sanitation’s (DWS) regional offices in Potchefstroom, as well as the Tlokwe Local Municipality need to join forces for a combined effort to accomplish the overarching research objective of achieving improved cooperative municipal governance and Integrated Water Resources Management (IWRM) to eventually ensure the safe and effective re-routing of water from the Klerkskraal Dam to the Potchefstroom water purification plant. Note: Since July 2014 the Department of Water Affairs (DWA) has changed to the Department of Water and Sanitation (DWS). / MA (Public Management and Governance), North-West University, Potchefstroom Campus, 2015