Three-dimensional Geological Modeling Methods and Applications -A

Abstract. The ideas and methods of modeling are: According to each well in the simulation area geology, well logging data, combined with deposit information to geostatistics theory, establish the spatial distribution of the various geological parameters model, using interpolation techniques to predict the geological parameters for each grid block, three-dimensional geological model should include quantitative structural model, sand skeleton model, physical model and the gas-water distribution model. Currently, the three-dimensional geological modeling software more sophisticated, this study selected the Schlumberger Petrel software as a tool for research. Geological modeling generally follow the step point → surface → body. That modeling data preparation, structure modeling, and reservoir modeling with parametric modeling. Establish A Geological Repository There are 187 drilling modeling work area, an area 61.7km2, modeling requires basic data can be divided into three categories: point data, surface data and volume data, point data mainly wells and wells dot attribute information, mainly a variety of surface data plan and structural map, mainly seismic volume data volume data, seismic inversion data volume. point data. All of the work area well abscissa, ordinate, make up the heart altitude, logging subdivision layer, inclined wells trajectory parameters, logs, well point attribute data, including rock, sandstone thickness, effective thickness, porosity, permeability and oil saturation. plane data. Longitudinal stratigraphic thickness larger gold belt region, seismic interpretation provides 10 structure surface (NG, D1, D2, D3, S1S, S1Z, S1X, S31, S32, S33), hierarchical data interpolation utilizing well in the modeling process calculated data structure surface of the remaining 52; the other side is sedimentary microfacies data plan data; third surface is oil and gas reservoirs plane data distribution, which is the oil and gas area plan area. Seismic interpretation of fault data, fault and fault data includes polygon data slice. Border and grid modeling accuracy Different mesh types, mesh size, mesh orientation, grid scale model simulation accuracy, reliability will have a huge impact. Therefore, to ensure the accuracy of the simulation results and rationality, to determine a reasonable grid system is a prerequisite for simulation studies. Corner points of the grid is a new type of grid, which uses eight vertex coordinates irregular hexahedral describe the 3rd International Conference on Management, Education, Information and Control (MEICI 2015

Evaluating the potential drilling success of exploration programmes using a three-dimensional geological model - a case study

The technological advancements in computing power in the last 30 years have enabled the practical visualization of complex geological environments in three-dimensional (3D) space. 3D models and their application in the mining industry are becoming increasingly important, for example, to identify future exploration areas and targets, for mineral assessment and evaluation, and prediction and planning of future drill-holes. However, acquiring borehole data is an expensive practice, with drilling programmes costing mining companies up to billions of dollars each year. Tighter financial constraints on exploration budgets result in more pressure being put on three-dimensional models to accurately identify future target areas. This article aims to evaluate the potential drilling success of simulated greenfield and brownfield exploration using a 3D geological model created of Leeuwpoort tin mine. These simulations investigate the probability of intersecting a mineralized zone of economic interest and evaluate how the probability is affected when the number of drill-holes and distance from a known intersection changes. Furthermore, these simulations attempt to obtain an indication for the minimum number of drill-holes required for a successful exploration campaign at the mine. The investigation also aims to establish a first-pass attempt towards developing a ‘favoured procedure’ for identifying potential exploration targets for tin deposits with geological and geochemical characteristics similar to Leeuwpoort. The results for the ‘favoured procedure’ established are statistically tested using the ‘bootstrapping’ method. By simulating various exploration scenarios, the study also emphasises the importance of predicting successful drilling, which aids in budgeting for drilling programmes as the minimum number of drillholes needed for a specific exploration project can be determined.https://journals.co.za/journal/saimmam2023Geolog

Modelling Orebody Structures: Block Merging Algorithms and Block Model Spatial Restructuring Strategies Given Mesh Surfaces of Geological Boundaries

This paper describes a framework for capturing geological structures in a 3D block model and improving its spatial fidelity given new mesh surfaces. Using surfaces that represent geological boundaries, the objectives are to identify areas where refinement is needed, increase spatial resolution to minimize surface approximation error, reduce redundancy to increase the compactness of the model and identify the geological domain on a block-by-block basis. These objectives are fulfilled by four system components which perform block-surface overlap detection, spatial structure decomposition, sub-blocks consolidation and block tagging, respectively. The main contributions are a coordinate-ascent merging algorithm and a flexible architecture for updating the spatial structure of a block model when given multiple surfaces, which emphasizes the ability to selectively retain or modify previously assigned block labels. The techniques employed include block-surface intersection analysis based on the separable axis theorem and ray-tracing for establishing the location of blocks relative to surfaces. To demonstrate the robustness and applicability of the proposed block merging strategy in a more narrow setting, it is used to reduce block fragmentation in an existing model where surfaces are not given and the minimum block size is fixed. To obtain further insight, a systematic comparison with octree subblocking subsequently illustrates the inherent constraints of dyadic hierarchical decomposition and the importance of inter-scale merging. The results show the proposed method produces merged blocks with less extreme aspect ratios and is highly amenable to parallel processing. The overall framework is applicable to orebody modelling given geological boundaries, and 3D segmentation more generally, where there is a need to delineate spatial regions using mesh surfaces within a block model.Comment: Keywords: Block merging algorithms, block model structure, spatial restructuring, mesh surfaces, subsurface modelling, geological structures, sub-blocking, boundary correction, domain identification, iterative refinement, geospatial information system. 27 page article, 26 figures, 6 tables, plus supplementary material (17 pages

Geostatistical evaluation of the eastern ore field one (EF1) orebody, Rosh Pinah zinc mine, Namibia

A Dissertation submitted in fulfilment of the requirements for the degree of Master of Science in Engineering to the Faculty of Engineering and the Built Environment, School of Mining Engineering, University of the Witwatersrand, Johannesburg, 2018The geometry, size and quality of a deposit are key parameters required for decision-making regarding mining methods, capital investments or divestments, economic viability and processing methods. The dissertation uses a quantitative approach to assess three geological modelling methods for orebody geometry. It applies Principal Components Analysis (PCA) in order to understand the variability and correlation in the data. The dissertation aims to determine the significance of increasing the composite size to 3 m for grade estimation and to estimate the tonnes and grades of the Eastern Ore Field 1 in-situ resource as on 31 December 2016. A MineSight, a Leapfrog and a hybrid of MineSight and Leapfrog modelling method were assessed, aiming to reduce the modelling time. The Minesight and Leapfrog hybrid model is recommended for modelling complex sedimentary exhalative deposits. The PCA was carried out using Matlab. Based on the correlation of 0.998, the first principal component increases with increasing Ag, Zn and Pb and it correlates most strongly with Ag. The second principal component increases with Zn, with a correlation of 0.985. With a correlation of 0.927, the third component increases with Mg. A 3 m composite size is recommended for estimating EF1 because the generated block-model estimates have lower means, standard deviations, variances and numbers of extreme outliers. The 3 m composite size is closer to the SMU at Rosh Pinah, and produces a better block estimate than 1.5 m composites, the later gives more tonnes and higher grade due to the volume-variance effect, which ultimately leads to overestimation of the mineral deposit. The total in-situ EF1 resource estimated using the Ordinary Kriging interpolation method as on 31 December 2016 was 814,100 tonnes at 8.58% Zn, 3.19% Pb and 79.22 ppm Ag.MT201

Resource and reserve calculation in seam-shaped mineral deposits; a new approach: “The pentahedral method”

In recent years, the introduction of specific software for the evaluation of geological resources and mineral reserves has increased significantly thanks to the use of block models capable of working with large databases and applicable to virtually all types of deposits. It is only in layered, tabular-shaped deposits where the use of block models poses certain drawbacks, not only in terms of visual representation but also during the process of interpolation. Other calculation methods for tabular bodies such as sections, polygons, and triangles work with 2D projections but not with 3D. The “Pentahedral” method described here is undoubtedly an innovative method that allows work to always be conducted in 3D, providing a fairly accurate representation of tabular bodies and making it possible to carry out calculations of resources and reserves using any interpolation method. It is demonstrated with figures and tables of the Carlés mineral deposit, a well-developed exoskarn gold deposit in northwestern Spain (Asturias) where the authors have worked extensively. The pentahedral method takes into account not only geological and stratigraphic data from the model interpolation, but also mining concepts such as “minimum thickness,” related to the minimum seam size that can be economically and technically mined, and “overbreak,” related to the dilution effect that appears during the mining process due to over-excavation

Integrating multidisciplinary modeling tools to support upstream mine waste management

Résumé Le drainage minier acide (DMA), suivant l’oxydation des sulfures déclenchée par l’oxygène atmosphérique et l’eau libre, occasionne une détérioration de la qualité de l’eau en terme d’acidité et de concentration des métaux et oxyanions. Le DMA constitue un danger environnemental d’ampleur mondiale vu son effet néfaste sur les systèmes aquatiques et les formes de vies fauniques et floristiques. Les contributions scientifiques menées par le gouvernement, l’industrie minière, les universités et les établissements de recherche se concentrent sur l’évaluation, la prévention et le traitement du DMA pour préserver les écosystèmes avoisinant les installations minières. La plupart des contributions scientifiques abordent les aspects avals de la gestion du DMA impliquant les étapes opérationnelles et post-fermeture du cycle minier. Peu de solutions pratiques ont été suggérées pour la phase de développement en raison du manque de rejets solides in-situ et les données expérimentales nécessaires pour envisager lesdites contributions scientifiques. Par conséquent, le concept de gestion en amont a reçu très peu d'attention. De même, les approches de modélisation utilisées pour prévoir le DMA sont largement étudiées. Bien qu'elles offrent de nombreux avantages, la majorité de ces études de modélisation sont réalisées pendant les phases d'exploitation et de fermeture du cycle minier, car elles abordent les stratégies de conception et la performance des scénarios de restauration. En outre, la recherche scientifique basée sur des approches interdisciplinaires pour atténuer le risque environnemental du DMA devrait être davantage mise en évidence et développée. La revue de la littérature souligne trois concepts principaux ; la géométallurgie, le principe de conception pour la fermeture et la réflexion en amont. La géométallurgie a été principalement développée pour dissoudre les limites interdisciplinaires entre le géologue, le métallurgiste et l'ingénieur minier afin d'optimiser les profits économiques et d'atténuer les risques techniques. Plus récemment, divers chercheurs ont inclus les enjeux environnementaux miniers dans la réflexion holistique de la géométallurgie. Le principe de conception pour la fermeture exige que les problèmes environnementaux potentiels soient pris en compte et planifiés avant et pendant les étapes de l'exploitation minière. De même, la réflexion en amont propose d'introduire des pratiques préventives dans les filières de gestion des rejets miniers. Ces pratiques doivent être entreprises dès les premières étapes possibles du cycle minier, appelées étapes en amont. Bien que de nombreuses contributions scientifiques aient abordé les concepts susmentionnés, elles se sont principalement concentrées sur des expériences en laboratoire et/ou sur le terrain. Aucune recherche n'a abordé la réconciliation entre les approches de modélisation pour soutenir l'atténuation des risques environnementaux du DMA. Le lien entre le géologue et le géochimiste environnemental est une préoccupation croissante qui devrait être abordée pour fournir au gestionnaire des rejets miniers de nouvelles options pour aller au-delà des méthodes de gestion conventionnelles. L'objectif principal du présent travail est de dissoudre les limites interdisciplinaires entre les approches de modélisation pertinentes pour améliorer la gestion en amont des rejets miniers solides et la prévention du DMA. Ainsi, trois objectifs principaux ont été définis : (1) lier la modélisation géologique et les attributs environnementaux du DMA pour effectuer une classification spatiale proactive des rejets miniers en fonction de leur risque environnemental inhérent; (2) réconcilier les outils de modélisation cinétique avec les contraintes des stades amonts du cycle minier (ex. le stade de développement) et (3) intégrer la composante spatiale développée selon le premier objectif et la dimension temporelle de la modélisation cinétique pour concevoir une approche de modélisation holistique permettant la classification en amont des rejets miniers et supportant l'atténuation des risques environnementaux. Pour atteindre ces objectifs, l'approche méthodologique a consisté dans un premier temps à lier les informations géologiques, collectées tout au long des campagnes du logging géologique, à la modélisation numérique. Ce lien a été établi par une approche stochastique qui relie les variables discrètes et continues du logging géologique. Le résultat de la simulation stochastique soutient la modélisation géologique 3D en accomplissant la densité spatiale adéquate des données numériques. Cette partie permettait d'établir des modèles numériques 3D décrivant la distribution spatiale d'un contaminant donné contenu dans la roche hôte. Par la suite, l'approche de modélisation cinétique a été réalisée pour simuler le pH résultant des principales réactions de génération et de neutralisation de l'acidité. Le modèle cinétique prend en compte des conditions hautement oxydantes et des réactions contrôlées par la réactivité minérale et la surface disponible. Par conséquent, la diffusion d'oxygène n'a pas été considérée comme l'étape limitant le processus d’oxydation-neutralisation. Le modèle a été calibré et étalonné par rapport à des tests cinétiques expérimentaux dont les conditions opératoires sont conformes à l'hypothèse du modèle. Enfin, les modèles spatiaux et cinétiques susmentionnés ont été intégrés pour permettre une classification dynamique de la roche abritant le minerai. Le modèle spatio-temporel intégré implique le logging géologique, la simulation stochastique, la modélisation géologique 3D, la modélisation cinétique et la modélisation de l’écoulement non saturé. Cette approche holistique décrit la distribution spatiale des principaux minéraux générateurs et neutralisants d'acide et entreprend une modélisation du transport réactif 1D pour chaque constituant volumétrique élémentaire, nommé voxel. Par la suite, une classification en amont des rejets miniers pourrait être effectuée en fonction de la teneur inhérente d'un contaminant donné dans la roche hôte et en fonction du pH qui pourrait être libéré à l'emplacement X, Y, Z du corps minéralisé si l'assemblage minéral correspondant est soumis à des conditions oxydantes. Les résultats de chaque axe sont résumés ci-dessous. L’utilisation de la modélisation géologique 3D pour la gestion des rejets miniers a permis de visualiser la distribution spatiale des contaminants dans un corps minéralisé et sa roche hôte. Par la suite, les responsables en matière de gestion pourraient facilement entreprendre la classification des stériles. À cet égard, le site minier Éléonore a fourni une base de données restreinte des teneurs en arsenic, l'élément le plus délétère dans son environnement minier, pour créer un modèle spatial 3D de la teneur en arsenic. Leapfrog Geo a été utilisé pour effectuer la modélisation géologique 3D et le logiciel de modélisation géostatistique de Stanford (SGeMS) a été utilisé pour entreprendre l'analyse du variogramme spatial. Le résultat de ce travail consiste en un modèle spatial 3D en multi-réalisation de la teneur en arsenic à travers le gisement et la roche encaissante. Chaque réalisation a été évaluée à l'aide des analyses chimiques mesurées pour souligner la fiabilité du modèle. Les résultats ont révélé un vaste halo géochimique d'arsenic qui s'étend jusqu'à 500 m du gisement d'or, avec jusqu'à 94 % des teneurs en arsenic dépassant 50 ppm. Les résultats de la modélisation cinétique à l'aide de PHREEQC ont montré un bon accord avec les données des mini-cellules d'altération. L'objectif principal de simulation du pH à l'aide de la modélisation cinétique des essais en mini-cellules d'altération a été atteint. Cependant, le modèle n'inclut pas les processus de rétention géochimique tels que la coprécipitation et la sorption. Étant conscient de ces limites, le modèle cinétique PHREEQC n'est pas conforme aux objectifs de conception liés à la restauration minière. Cependant, il est conforme aux études préliminaires tout au long de la phase de développement, qui a peu bénéficié des outils de modélisation géochimique. Le principal atout du modèle cinétique proposé est la capacité d'entreprendre une analyse paramétrique pour l'identification en amont des risques en se basant sur une base de données restreinte et un raisonnement de modélisation conservateur. À cet égard, les données d'entrée sont constituées de la caractérisation minéralogique habituelle, les tests de mini-cellule d'altération et les taux de réactivité minérale tirés de la littérature, respectant ainsi deux contraintes principales qui orientent l'étape de développement : la disponibilité des matériaux et le coût d'évaluation. Les résultats du modèle intégrant la modélisation spatiale et la modélisation du transport réactif montrent l'évolution spatio-temporelle du pH tout au long du plan central d'exploitation minière. À cet égard, 527 simulations de transport réactif ont été effectuées tout au long du plan minier composé de voxels de 40х40х40 mètres. Le géomodèle spatio-temporel met en évidence l'effet de la réactivité des minéraux neutralisants sur le pH lors de l'oxydation des sulfures. L'intégration de la géologie et la géochimie environnementale est la solution clé pour des opportunités de production plus propres. Le présent projet a fait progresser les connaissances sur la classification en amont des rejets miniers et a mis en place des méthodes prometteuses pour intégrer des approches de modélisation multidisciplinaires en vue d'un meilleur contrôle des rejets solides dans les mines métalliques. Les méthodes appliquées ici ne se limitent pas aux études de cas abordées et pourraient être appliquées à d'autres projets miniers atteignant les stades de développement et/ou d'exploitation. Abstract Acid mine drainage (AMD), following oxidation of sulphides triggered by atmospheric oxygen and through-flowing water, causes water quality exceedances in terms of water acidity and metals and oxyanions concentrations. AMD is a worldwide ecological-security threat with the ability to toxify freshwaters and impair life forms and their support systems. Scientific research contributions adopted by governments, the mining industry, universities, and research establishments focus on assessment, prevention, and treatment of AMD to safeguard ecosystems neighbouring mine facilities. Most of the scientific research contributions tackle downstream aspects of the AMD management involving operational and post-closure stages of the mine life. Few practical solutions were suggested during the development stage because of the lack of in-situ waste materials and the data-intensive nature of the solutions being used. Consequently, the concept of upstream management has received very little attention. Likewise, modeling approaches used to forecast AMD are extensively investigated. Although they provide many benefits, the majority of these modeling case studies are carried out during the operation and closure stages of the mine life cycle as they tackle design strategies and the performance of reclamation scenarios. Besides, scientific research based upon cross-disciplinary approaches to mitigate AMD environmental risk should be further highlighted and developed. The literature review underlines three main concepts; the geometallurgy, the design for closure principle and the upstream thinking. The geometallurgy was primarily developed to dissolve the interdisciplinary barriers among the geologist, the metallurgist and the mining engineer to optimize the economic profits and mitigate technical risks. More recently, miscellaneous researchers included the mining environmental issues in the geometallurgical holistic thinking. The design for closure principle requires that potential environmental issues are considered and planned for both before and during the production stages of mining operation. Likewise, the upstream thinking proposes introducing preventive practices into mine waste management streams. These practices should be undertaken at the earliest possible stages of a mine’s life cycle, known as upstream stages. Although numerous scientific contributions tackled the aforementioned concepts, they were mainly focused on lab and/or field experiments. No research has addressed the bridging among modeling approaches to support the AMD environmental risk mitigation. The nexus between the geologist and the environmental geochemist is a growing concern that should be addressed to provide the mine waste manager with novel options to move beyond conventional management methods. The main aim of the present work is to dissolve interdisciplinary barriers among the relevant modeling approaches to enhance mine waste upstream management and AMD prevention. Accordingly, three main objectives were defined: (1) bridging geological modeling and AMD environmental attributes to perform proactive spatial classification of mine waste based on their inherent environmental risk; (2) using the time dimension of the AMD geochemical modeling modules that should comply with the framework of the upstream stages of the mine life (e.g., the development stage); and (3) integrating the spatial component developed according to the first objective and the temporal dimension mentioned in the second objective to conceive a holistic modeling approach enabling upstream mine waste classification and supporting environmental risk mitigation. To achieve these objectives, the methodological approach consisted firstly of linking the geological information, collected throughout the geological logging surveys, to the numerical modeling. This linkage was established through a stochastic approach that relates the discrete and continuous variables of the geological logging. The outcome of the stochastic simulation supports the subsequent 3D geological modeling as it fulfills the data-density requirement. This part enables the establishment of 3D numerical models describing the spatial distribution of a given contaminant contained in the host rock. Thereafter, the kinetic modeling approach was performed to simulate the pH resulting from the main acid-generating and acid-neutralizing reactions. The kinetic model considers highly oxidizing conditions and surface-controlled reactions. Consequently, oxygen diffusion was not considered as the rate-limiting step. The model was calibrated and benchmarked against experimental kinetic tests whose operating conditions comply with the model hypothesis. Finally, the aforementioned spatial and kinetic models were integrated to enable a dynamic classification of the ore hosting rock. The spatiotemporal integrated model involves geological logging, stochastic simulation, 3D geological modeling, kinetic modeling and unsaturated environment modeling. This holistic approach portrays the spatial distribution of the main acid-generating and acid-neutralizing minerals and undertakes a 1D reactive transport modeling for each elementary volumetric constituent, named voxel. Subsequently, an upstream mine waste classification could be carried out based on the inherent content of a given contaminant in the host rock and based upon the pH that could be released at X, Y, Z location of the orebody if the corresponding mineral assemblage undergoes highly oxidizing conditions. Results of each part are summarized in the following. Repurposing the 3D geological modeling for mine waste management allowed for the visualization of hazardous metals spatial distribution throughout an orebody and its hosting rock. Subsequently, a mine manager could seamlessly undertake waste rock classification. In this respect, the Éléonore mine site provided restricted grades of arsenic, the most deleterious element within the mine setting, to create a 3D spatial model of arsenic content. Leapfrog Geo was used to perform the 3D geological modeling and the Stanford Geostatistical Modeling Software (SGeMS) was used to undertake the spatial variogram analysis. The outcome of this work consists of multi-realization 3D spatial model of arsenic grade across the ore deposit and the hosting rock. Each realization was assessed using available chemical analyses to underline the model’s reliability. The results revealed a spacious geochemical halo of arsenic that reaches up to 500 m away from the gold deposit, with up to 94% of arsenic grades exceeding 50 ppm. Results from the kinetic modeling using PHREEQC exhibited a good agreement with weathering cell data. The main objective of simulating the pH using kinetic modeling of weathering cell tests was fulfilled. However, the model does not include geochemical retention processes such as coprecipitation and sorption. Being cognizant of these limitations, the PHREEQC kinetic model does not conform to design purposes related to mine reclamation. However, it complies with the upstream scoping studies along the development stage, which has barely benefited from geochemical modeling tools. The main asset of the present kinetic model is the ability to undertake parametric analysis for upstream risk identification based upon restricted datasets and conservative modeling reasoning. In this regard, the input datasets consist of the usual mineralogical characterization, weathering cell tests, and literature rate laws, thereby abiding by two main constraints that steer the development stage: material availability and assessment cost. Results from the model integrating the spatial modeling and reactive transport modeling displays the spatio-temporal evolution of the pH throughout the central plane of mining. In this regard, 527 reactive transport simulations were performed throughout the mining plane consisting of 40х40х40 meters voxels. The spatiotemporal geomodel highlights the effect of neutralizing minerals reactivity on the pH during the sulphide oxidation. Geology and environmental geochemistry integration is the key solution for cleaner production opportunities. The present project progressed the knowledge of upstream mine waste classification and set up promising methods to integrate multidisciplinary modeling approaches for the sake of a better control over solid waste in hard rock mines. Methods applied herein are not limited to the case studies framework and could be applied to other mining projects reaching development and/or operation stages

A review of archean orogenic gold deposits in greenstone belts and the Slave Province : exploration in the Yellowknife domain, NWT, Canada

A review of Archean granite-greenstone terranes, orogenic gold deposits, the Slave Province and modern exploration tools, techniques and methods was conducted to identify prospective areas in the Yellowknife domain for hosting orogenic gold deposits and illustrate the best exploration methods for delineating this deposit type. This study identifies Archean granite-greenstone terranes as economically important hosts to quartz-carbonate vein-hosted orogenic gold deposits. These deposits occur at convergent plate margins, but can also be related to local extensional tectonics within a convergent setting. Heat generated from tectonic processes can trigger hydrothermal fluid movement along first-order faults and shear zones. Precipitation of gold-bearing quartz-carbonate veins from the hydrothermal fluids occurs in second- and third-order faults and shear zones related to the first-order structures. This study also identifies the Archean Slave Province in northern Canada as a well-endowed craton with numerous orogenic gold deposits, diamondiferous kimberlites, VMS deposits and several other mineralization styles. In particular, three greenstone belts (Yellowknife, Cameron River and Beaulieu River) associated with likely first-order structures are comprised of prospective rocks for hosting orogenic gold and VMS mineralization. The Yellowknife greenstone belt hosts the past-producing and former world-class Con and Giant orogenic gold deposits, but has been little explored with modern exploration techniques. The Cameron River and Beaulieu River greenstone belts host numerous base and precious metal VMS and BIF-hosted orogenic gold prospects and deposits, indicating mineralization is present. There is considerable potential for significant discoveries to be made using modern exploration techniques in the greenstone belts; however, exploration in the region has been hindered over the past decade by ongoing political negotiations. Once the political negotiations are finalized, application of modern exploration methods and techniques in the prospective greenstone belts should be carried out. Regional scale methodologies should be applied to generate targets using predictive modelling, implicit 3D modelling, 3D geochemistry and exploration targeting so decisions defining a businesses strategy for ground acquisition of high priority targets are made using quantitative analysis. Once ground is acquired, field-based exploration for orogenic gold and VMS deposits should include geological mapping with a focus on structural geology, geochemical sampling and airborne magnetic, radiometric and EM geophysical surveys. Prior to reconnaissance drilling, integration of all data layers and interpretation within a common 3D earth model should be conducted. Following successful reconnaissance drilling, definition drilling along strike and down dip of intersected mineralization, combined with borehole geophysics, should be carried out to delineate the extent of mineralization

A three-dimensional model for the Leeuwpoort tin mine and its application to exploration prediction

Due to tighter financial margins, the need for better knowledge of grade data is required. Geological models allow the user to have a better understanding of the geological environment in which mining is taking place. Three dimensional (3D) geological, ore deposit, and mining models are therefore becoming increasingly important in the mining industry. 3D models are being used more frequently for mineral potential targeting, as well as resource assessment, because good quality geological models allow the user to determine grade domains within mineralized environments. The aim of this thesis is to create a geological model for Leeuwpoort Tin Mine (C-Mine) and test the applicability of this 3D model for exploration purposes. The 3D geological and interpolant models created of Leeuwpoort Mine was used to determine the probability of intersecting a lode of economic interest, if 500 drillholes were randomly drilled in a specific boundary. Resampling was conducted using the Bootstrap method, in order to determine how the probability will change as different borehole sample sizes are used. When conducting a quantitative resource assessment of mineral deposits, grade-tonnage models form a fundamental part in the estimation and prediction process. Grade and tonnage models are used during quantitative resource assessment to predict the values of the known deposits for a specific type, and can also be used to determine the potential value of undiscovered deposits in a specific area. If sufficient geological data is available, the tonnage of mineralized bodies can be calculated and a grade-tonnage model can be created from the 3D geological model. 3D models can be used as a summary and visualization tool for geological environments. The 3D visualization of deposit give a much better representation of the orebody than 2D cross-sections from a few drillholes. The effectiveness of 3D model, as a possible tool for mining, is limited by the quality and quantity of the data. Poor quality data will result in poor quality models, whereas limited data will result in a higher level of uncertainty of the estimates based from these 3D models. However, even limited data can be used to visualize geological environments. In the case of Leeuwpoort Mine, limited structural and lithological information was available to create the 3D models. However, the provided peg index noted the positions of the mine pegs, and consequently indicate where the lodes were mined. In this instance, with limited mine peg data, the lode “volumes” could be reconstructed. The peg index was used to delineate the mining area in order to model the lodes, as well as interpret geological features. Once the lode “volumes” were created in the 3D model, the specific orezone with the geometric relationship between individual lodes of Leeuwpoort Mine could be defined. In addition, the probability of intersecting a certain number of lodes was derived from these modelled surfaces, resulting in the estimation for the predicted probability of success. The 3D geological and interpolant models created of Leeuwpoort Mine were used to determine the probability of intersecting a lode of economic interest, if exploration drilling were to be done. Resampling was conducted using the Bootstrap method, in order to determine how reliable this prediction is as a function of number of boreholes. The results obtained from the Bootstrap analysis indicates that the average probability of intersecting a lode of economic significance, for each of the different sample sizes stays the same. A higher level of confidence in the probability of intersecting a lode can be assumed for areas that have large quantities of drilling. If a geological environment similar to that of Leeuwpoort Mine is considered for an exploration project, the chances of intersecting an economical orebody or lode during exploration is very low. When considering Greenfields exploration (virgin exploration), the chances of intersecting a mineralized body is extremely low, and a lot of money has to be invested to obtain meaningful results. However, if Brownfields exploration (exploration on a known area) takes place, the chances of intersecting a mineralized body is higher, because prior knowledge of the area exists and can be used to make informed decisions on where to drill. Less money needs to be invested for the drilling than for Greenfields exploration. In the case of Leeuwpoort Mine, unfortunately even Brownfields exploration will bear a very limited chance of identifying a mineralized body, which means that in such a scenario, the information about potential success rate of a drilling program is even more important for drilling and financial planning.Dissertation (MSc)--University of Pretoria, 2017.GeologyMScUnrestricte

Towards a National 3D Mapping Product for Great Britain

Knowing where something happens and where people are located can be critically important to understand issues ranging from climate change to road accidents, crime, schooling, transport and much more. To analyse these spatial problems, two-dimensional representations of the world, such as paper or digital maps, have traditionally been used. Geographic information systems (GIS) are the tools that enable capture, modelling, storage, retrieval, sharing, manipulation, analysis, and presentation of geographically referenced data. Three-dimensional geographic information (3D GI) is data that can represent real-world features as objects in 3D space. 3D GI offers additional functionality not possible in 2D, including analysing and querying volume, visibility, surface and sub-surface, and shadowing. This thesis contributes to the understanding of user requirements and other data related considerations in the production of 3D geographic information at a national level. The study promotes Ordnance Survey’s efforts in developing a 3D geographic product through: (1) identifying potential applications; (2) analysing existing 3D city modelling approaches; (3) eliciting and formalising user requirements; (4) developing metrics to describe the usefulness of 3D data and; (5) evaluating the commerciality of 3D GI. A review of current applications of 3D showed that visualisation dominated as the main use, allowing for better communication, and supporting decision-making processes. Reflecting this, an examination of existing 3D city models showed that, despite the varying modelling approaches, there was a general focus towards accurate and realistic geometric representation of the urban environment. Web-based questionnaires and semi-structured interviews revealed that while some applications (e.g. subsurface, photovoltaics, air and noise quality) lead the field with a high adoption of 3D, others were laggards due to organisational inertia (e.g. insurance, facilities management). Individuals expressed positive views on the use of 3D, but still struggled to justify the value and business case. Simple building geometry coupled with non-building thematic classes was perceived to be most useful by users. Several metrics were developed to quantify and compare the characteristics of thirty-three 3D datasets. Results showed that geometry-based metrics such as minimum feature length or Euler characteristic can be used to provide additional information as part of fitness-for-purpose evaluations. The metrics can also contribute to quality control during data production. An investigation into the commercial opportunities explored the economic value of 3D, the market size of 3D data in Great Britain, as well as proposed a number of opportunities within the wider business context of Ordnance Survey