Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2008. / Includes bibliographical references. / Segmentation and crustal accretion at oceanic transform fault systems are investigated through a combination of geophysical data analysis and geodynamical and geochemical modeling. Chapter 1 examines the effect of fault segmentation on the maximum predicted earthquake magnitude of an oceanic transform fault system. Results of thermal modeling suggest that fault segmentation by intra- transform spreading centers (ITSC) drastically reduces the available brittle area of a transform fault and thus limits the available earthquake rupture area. Coulomb stress models suggest that long ITSCs will prohibit static stress interaction between segments of a transform system and further limit the maximum possible magnitude of a given transform fault earthquake. In Chapter 2, gravity anomalies from a global set of oceanic transform fault systems are investigated. Surprisingly, negative residual mantle Bouguer gravity anomalies are found within fast-slipping transform fault domains. These gravity observations suggest a mass deficit within fast-slipping transform faults, which may result from porosity variations, mantle serpentinization, and/or crustal thickness variations. Two-dimensional forward modeling and the correlation of the negative gravity anomalies to bathymetric highs indicate crustal thickness excesses in these locations. Finally, in Chapter 3, mantle thermal and melting models for a visco-plastic rheology are developed to investigate the process of mantle melting and crustal accretion at ITSCs within segmented transform faults, and are applied to the Siqueiros transform fault system. Models in which melt migrates into the transform fault domain from a large region of the mantle best explain the gravity-derived crustal thickness variations observed at the Siqueiros transform. Furthermore, a mantle potential temperature of 1350⁰C and fractional crystallization at depths of 9 - 15.5 km best explain the major element composition variation observed at the Siqueiros transform. / by Patricia Michelle Marie Gregg. / Ph.D.

Numerical methods and specifically the finite element method have improved significantly since their introduction in the 60's. These advances were mainly in: 1) introducing higher-order elements, 2) developing effective solution schemes, 3) developing sophisticated means of modeling the constitutive behavior of geotechnical materials, and 4) introducing iteration techniques to model material non-linearity. This thesis, on the other hand, deals with the topic of modeling the boundary conditions of the finite element problem. Typically, the boundary conditions will be approximated by specifying displacement constraints. such as restraining the bottom boundary of the finite element mesh against displacements in the horizontal and vertical directions (x- and y-directions). Where bedrock or dense residual soils underlie the soft foundation soil at a relatively shallow depth, this is a good assumption. However. when soft soil is encountered for large depths, the assumption of zero movement constraints for a mesh boundary at a shallower depth than the actual bedrock will result in a serious underestimation of stresses and displacements. By coupling boundary elements to the finite elements and using them to model the infinite extent of the foundation soil, a more realistic answer is obtained. Employing the coupled boundary element - finite element method, four cases were analyzed and the results compared to values of the pure finite element method. The results show that the coupled method indeed yielded higher stress- and displacement-values, indicating that the pure finite element method underestimates stresses and displacements when modeling very deep soils. / Master of Science

Thesis (PhD (Geology))--University of Stellenbosch, 1997. / 1123 leaves printed on single pages, preliminary pages and numbered pages 1-286. Includes bibliography, list of figures and tables and explanation of abbreviations used. / Digitized at 600 dpi grayscale to pdf format (OCR), using a Bizhub 250 Konica Minolta Scanner. / ENGLISH ABSTRACT: This first comprehensive study of the petroleum geochemistry of the Bredasdorp Basin, and the adjacent Southern Outeniqua Basin, documents the characteristic large number of hydrocarbon shows and the four regionally distinctive marine source rocks. Detailed correlation of reservoired hydrocarbons with source rock bitumens shows that two source rocks have expelled oil in commercial quantities and two others have expelled commercial quantities of wet gas/condensate. In contrast with earlier studies which indicated that thermal 'gradualism' prevailed, this study indicates that the post-rift thermal history of the basin is very complex. Post-rift cool-down is punctuated by periods of rapidly increasing heat flow resulting in much of the maturation being localised in time. These periods of increased heating coincide with regional plate tectonism. The associated thermal uplift and downwarp effects govern the periods of trap formation and control the hydrocarbon migration direction. Migration distances of these hydrocarbons are described and show inter alia that oil migrates no more than -7-10 km but gas migrates regionally. Two regional episodes of meteoric water flushing reduce sandstone cementation in palaeo-highs forming potential reservoirs at specific times. The unusually low salinity of remnants of this water in some sandstones help characterise these two main migration conduits. A highly detailed hydrocarbon correlation scheme derived from gas, light oil and biomarker data has been established which differentiates products of the four active source rocks and helps characterise the oil-oil, oil-source and source-source pairs. It is evident from these correlations that two periods of migration and reservoiring occurred at 50-60 Ma and 0-10 Ma. As a result, source-reservoir plays which characterise certain areas of the basin as predominantly oil or gas prone can be described. These correlations also highlight areas where mixtures of hydrocarbons are common and where some of the early reservoired oil has been displaced to new locations, constituting potential new exploration plays. Source rocks for some of the analysed hydrocarbons have yet to be found and may not even have been drilled to date. One such source rock appears to be located in the Southern Outeniqua Basin, making that area a potential target for further exploration. This study resolved the common heritage of the source rocks and reservoir sandstones which form part of the Outeniqua petroleum system. The hydrocarbon volumes available to this system show that by world standards it is indeed significant. / AFRIKAANSE OPSOMMING: Die groot aantal koolwaterstof voorkomste asook vier streekskenmerkende mariene brongesteentes word in hierdie eerste omvattende studie van die petroleumgeochemie van die Bredasdorp-kom en die aangrensende Suidelike Outeniqua-kom saamgevat. Gedetaileerde korrelasies van die opgegaarde koolwaterstowwe met brongesteente bitumen, dui daarop dat twee van die vier geidentifiseerde brongesteentes olie in kommersiele hoeveelhede uitgeset het. Die ander twee het kommersiele hoeveelhede nat gas-kondensaat uitgeset. In teenstelling met vroeer studies wat daarop gedui het dat termale 'gradualisme' voorgekom het, dui hierdie studie daarop dat die na-riftermale geskiedenis van die kom baie meer kompleks is. Verskeie periodes van versnelde toename in hittevloei het voorgekom in die na-rifse verkoeling. Dit het daartoe gelei dat veroudering plaaslik binne 'n beperkte tydsverloop plaasvind. Hierdie periodes van hittetoename stem ooreen met die regionale plaattektoniek. Die geassosieerde termiese opheffing en afwaartse vervormingseffek, beheer die totstandkoming van opvanggebiede en die migrasierigting van die koolwaterstowwe. Migrasie-afstande van die koolwaterstowwe word bespreek en wys inter alia daarop dat olie nie verder as -7-10 km beweeg nie, maar gasmigrasie vind regionaal plaas. Twee kort episodes van meteoriese wateruitsetting, het sandsteensementasie in palaeohoogsliggende gebiede verminder wat potensiele reservoirs gevorm het op spesifieke tye. Die ongewone lae soutvlakte van oorblyfsels van die water in sekere sandstene help om die twee vernaamste migrasieroetes te kenmerk. 'n Hoogs omvattende koolwaterstof-korrelasieskema wat van gas, ligte olie en biomerkerdata verkry is, is opgestel. Die skema het onderskei tussen produkte van die vier aktiewe brongesteentes en help om die olie-olie, olie-bron en bron-bron pare te karakteriseer. Dit is duidelik van die korrelasies dat twee periodes van migrasie en opgaring plaasgevind het ongeveer teen -50-60 Ma en 0-10 Ma. Gevolglik kan bronreservoir omskrywings wat sekere dele van die kom karakteriseer as grotendeels olie of gas-ontvanklik beskryf word. Hierdie korrelasies beklemtoon ook areas waar mengsels van koolwaterstowwe algemeen voorkom en waar sekere van die vroeer opgegaarde olie verplaas is na nuwe lokaliteite, wat nuwe eksplorasieteikens daarstel. Brongesteentes vir sekere van die ge-analiseerde koolwaterstowwe, moet nog gevind word en is tot op hede nog nie raakgeboor nie. Een so 'n brongesteente kom voor in die Suidelike Outeniqua-kom, wat daardie area 'n potenslele teiken vir verdere eksplorasie maak. Die studie het die gesamentlike oorsprong van die brongesteente en reservoirsandsteen, wat deel is van die Outeniqua Petroleumsisteem, geidentifseer. Die koolwaterstofvolumes wat beskikbaar is vir die sisteem wys dat, gemeet teen wêreldstandaarde, dit wel beduidend is.

The thesis presents the application of the magnetotelluric (MT) sounding method to image Earth’s crust in Oman and South Australia. The aim of these MT surveys is to provide constraints on the geological interpretation of emplacement scenarios and the tectonic evolution of the geological domain. The thesis concentrates on the methodological aspects of the MT technique, e.g. the data analysis and modelling of electromagnetic fields. The phase tensor approach by Caldwell et al. (2004) is applied to the data and provides insights into the dimensionality of the MT data in even complex and electrically distorted terranes. Modelling and inversion of the MT data is performed with various 2-D and 3-D codes to show how the interpretation of the data can benefit from multiple modelling approaches. Data collected in a 2-D survey across the Oman ophiolite mountains show complex behaviour and 2-D inversion and 3-D forward modelling resolve ambiguities in the emplacement scenario of the Oman ophiolite. It is believed that initial underthrusting of the Jurassic-Cretaceous oceanic lithosphere was followed by exhumation. Further oceanic thrusting subsequently led to rising of lower-plate eclogites and eventually gravitational collapse of the ophiolite onto the margin (Gray et al., 2000). The 3-D inversion code by (Siripunvaraporn et al., 2005a) was expanded to incorporate static shift corrections and inversion model misfits have therefore improved significantly compared to inversion models without static shift correction. 2-D and 3-D surveys across the South Australian Gawler Craton reveal deep crustal conductors which are connected to near surface mineralisation systems of the IOCG Olympic Dam deposit in the north-eastern part of the craton and the Au-dominated central Gawler Craton provinces. / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

Thesis (M.S.) -- Mississippi State University. Department of Geosciences. / Title from title screen. Includes bibliographical references.

Submitted by Luana Fernandes do Nascimento (luanaf_n@yahoo.com.br) on 2016-12-14T18:53:09Z No. of bitstreams: 1 Luana_Unesp_Mestrado_Final.pdf: 15010826 bytes, checksum: d648b060d92f0de0538ad7924f8a3ce0 (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-12-19T17:24:32Z (GMT) No. of bitstreams: 1 nacimento_lf_me_rcla.pdf: 15010826 bytes, checksum: d648b060d92f0de0538ad7924f8a3ce0 (MD5) / Made available in DSpace on 2016-12-19T17:24:32Z (GMT). No. of bitstreams: 1 nacimento_lf_me_rcla.pdf: 15010826 bytes, checksum: d648b060d92f0de0538ad7924f8a3ce0 (MD5) Previous issue date: 2016-10-21 / Outra / A área de estudo corresponde a um campo produtor de hidrocarbonetos situado no sudoeste da Bacia de Campos a 80 km da costa. Esta região produz hidrocarbonetos de diversos níveis estratigráficos, entre eles, os carbonatos do Albiano, foco deste estudo. O alto interesse econômico dos carbonatos no setor petrolífero mundial e a complexidade da sua análise nos dados geofísicos, justifica a importância desta pesquisa na definição de um método que auxilie na caracterização da distribuição regional da propriedade da rocha reservatório, neste caso, a porosidade. Neste contexto, este trabalho objetiva a determinação da heterogeneidade lateral e vertical das propriedades das rochas reservatórios, por meio da construção de um modelo geológico 3D de porosidade dos dois principais reservatórios identificados na Formação Quissamã (Grupo Macaé). Com esta finalidade, o método incluiu seis etapas principais: análise dos perfis geofísicos e correlação de poços, interpretação sísmica, conversão tempo x profundidade, análise de atributos sísmicos, análise geoestatística e modelagem geológica por meio da aplicação de Simulação Sequencial Gaussiana. Como níveis de referência, foram interpretados os intervalos estratigráficos correspondentes à Formação Outeiro e, na Formação Quissamã, os níveis Q1 e reservatórios R1 e R2 (principais produtores do campo). Estes níveis foram definidos com base na mudança do padrão geométrico dos perfis geofísicos de raio gama (RG), densidade (RHOB) e porosidade (Nphi). Os intervalos estudados estão distribuídos em um alto estrutural com eixo principal de direção NW-SE delimitado por falhas e pela própria geometria do banco carbonático. Na porção central do campo, este alto estrutural apresenta valores altos de porosidade (>21%), e se destacou no mapa de resistividade como portador de hidrocarbonetos nos reservatórios R1 e R2. Estas fácies carbonáticas variam para norte e nordeste da área com valores de porosidade mais baixos (<18%), representando a diminuição da qualidade dos reservatórios para estas regiões; esta observação, aliada à influência das falhas a sudoeste e nordeste do banco, permitiu classificar a trapa destes reservatórios como estrutural-estratigráfica. O sistema de falhas predominante na área de estudo corresponde ao NW-SE, que originou estruturas do tipo rollovers e horsts com potencial reservatório. Estas falhas abateram os blocos a sudeste e sul, que foram realçados nos mapas de atributos sísmicos como portadores de alta porosidade, comprovados por gráficos de correlação com coeficiente R2>0,65. Esta análise foi utilizada para determinar o modelo geológico 3D de porosidade, gerado por Simulação Sequencial Gaussiana. O resultado consistiu em uma representação coerente, com maior grau de certeza no alto estrutural central, que possui maior quantidade de dados de poços. Apesar das áreas a sudoeste e sul não apresentarem dados de poços, o método de Simulação Sequencial Gaussiana extrapolou altos valores de porosidade em 23% das 30 realizações geradas. / The study area is an ancient field and hydrocarbon producer, located in the southwest of the Campos Basin, in a water depth of approximately 100 m and 80 km distant from the coast. This region produces hydrocarbon from multiple stratigraphic layers, among them, there are the Albian carbonates, the focus of this research. The high economic interest in carbonates plays by the global oil industry and the complexity of their analysis in geophysical data, justifies the importance of this research to define a method, which determine the regional distribution of the property of the reservoir rock, in this case, the porosity. In this context, this study aims to determine the lateral and vertical heterogeneity of the properties of the reservoir rocks through the construction of a 3D geologic model of porosity from two main reservoirs in Quissamã formation (Macae Group). For this purpose, the method includes six major steps: analysis of well log and correlation of wells, seismic interpretation, conversion time vs. depth, analysis of seismic attributes, geostatistical analysis and geological modeling through the application of Gaussian simulation. The stratigraphic intervals such as Outeiro Formation and Quissamã Formation, which include level Q1, R1 and R2 reservoirs (main producers of the field) were interpreted as reference levels. These intervals were defined based on the change of the geometric standard of the geophysical profiles, as gamma ray (GR), density (RHOB) and porosity (Nphi). These levels are distributed in a carbonate bank with main axis in NW-SE direction, delimited by faults and its geometry. It was observed a structural high in the central portion of the field presenting high porosity values (> 21 %) that was highlighted in the resistivity maps as filled by oil in the reservoirs R1 and R2. These carbonate facies vary to the north and northeast of the area with lower values representing the decline in the quality of the reservoirs for these regions; this observation combined with the influence of the faults , in the southwest and northeast of the bank, allowed to classify the trap of these reservoirs as structural-stratigraphic. The predominant fault system in the study area corresponds to the NW-SE, which formed structures like rollovers and horsts with potential of being reservoir. These faults shot down the block to the southwest and south, which were highlighted in the maps of seismic attributes as having high porosity, supported by cross plots with correlation coefficient of R2> 0.65. This analysis was used to determine the 3D geologic model of porosity, generated by Gaussian simulation, most appropriate to the context of the geological area. The result was a coherent representation with greater certainty in the central structural high that presents a higher amount of well data. Despite the southwest and south areas do not present well data, the method was efficient in interpolate high values of porosity in 23% of 30 generated realizations. / PRH 05: 6000.0082154.13.4

Rapid technological advancements and growing environmental consciousness created a shifting dynamic of metal demand within the context of contemporary global challenges. The metals play a pivotal role in this transformation and remarkable surge in demand is expected. Mining districts such as the Kiruna area in northern Sweden, provide access to raw materials, assuring supply chain security, sustainability, and an environmentally friendly future. The district is part of the northern Norrbotten ore province, Sweden and is known for hosting the Kiruna-type iron oxide-apatite (IOA) deposits with associated magnetite-hematite-REE ores such as the Per Geijer deposits, and a range of other deposits, including the Viscaria Cu-(Fe-Zn), Pahtohavare Cu-Au and the Rakkurijärvi iron oxide-copper-gold (IOCG) deposits.  As the discoveries of significant near-surface deposits are declining, mining companies face a pivotal choice between pursuing resource extraction from lower-grade reserves or to focus on deeper exploration targets. The geological understanding of the subsurface decreases with increasing depth, and the reliance on geophysical techniques becomes more important in reducing the search space. Using geophysics to locate and understand elements of a mineral system requires a good understanding of the physical and chemical properties of the rocks that can be translated into geological implications. Mineral system knowledge and geological concepts can be translated into geological models that can be further used in geophysical inversions with the aim of improving targeting by iterative modeling. A geophysical inversion is in fact a realization of a physical property model, therefore the value added by the geophysical model is dependent of how well the relationship between the geology and its petrophysical signature is understood. The petrophysical characterization of geological environments offers the possibility to improve the understanding of geophysical responses, serving as a link in iterative geological-geophysical modeling.  The approach presented in the current study includes the building of three-dimensional lithological and structural framework models, and investigating the petrophysical footprint in connection with lithology, alteration, and rock fabric from the Kiruna mining district. Geological modeling and petrophysical characterization are important components within the comprehensive mineral system modeling framework and enhance geophysical investigations aimed at detecting and assessing iron oxide mineral systems. A rule-based hybrid implicit-explicit geological modeling technique proved to be useful in the integration of surface and subsurface data of the Kiruna mining district, and a structural framework and geological model was produced that provides insights into the relationship between lithological units and structures. Drill core observations indicate a competency contrast between lithological units confirming previous surface-based observations. Deposit scale structural analysis in connection with the geological models indicated the proximity of NW-SE to SW-NE trending brittle conjugate fault networks with iron-oxide apatite ore lenses, revealing juxtaposition of individual ore lenses. Complementing structural analysis and geological modeling, petrophysical characterization in connection with lithogeochemical, mineralogical, and textural investigations revealed that density and p-wave seismic velocity can be used as a general lithological indicator, while magnetic susceptibility is influenced by secondary processes. Heterogeneous strain accommodation by lithological units indicates a strong influence on density, seismic properties, and the ferromagnetic properties of the samples. Metasomatic processes alter the intrinsic properties of the samples by increasing or decreasing the physical properties of the rocks from the Kiruna area, by controlling the feldspar, mica, magnetite, and ferromagnesian mineral content. Nevertheless, an extensive sample population must be investigated to understand the large-scale effects. The present work serves as a foundation for quantitatively integrated exploration models that use geological models and petrophysical characterization as calibration tools to model mineral systems.

La vallée de la Komadougou Yobé constitue un site privilégié de recharge de l'aquifère quaternaire du bassin du lac Tchad. Depuis les années 1980, le développement des cultures de rente (p. ex. poivron) a conduit à un doublement des surfaces irriguées (1995-2005) dans sa partie aval. Afin de quantifier la recharge supplémentaire induite, une modélisation des flux hydriques verticaux dans la zone non-saturée (0-8 m) a été engagée. La première étape, objet de ce travail de thèse, consiste à décrire l'organisation spatiale et les propriétés hydrodynamiques des corps sédimentaires constitutifs de l'alluvium.Des forages à travers les formations superficielles mettent en évidence des alternances sable-sable argileux dans la totalité de la zone non-saturée, conséquence des migrations du lit mineur de la Komadougou Yobé. Le calcul de la corrélation entre les forages indique une forte analogie avec les hétérogénéités identifiées en surface à partir de données de télédétection (Landsat 7 binarisée). Ces données sont donc utilisées pour l'apprentissage de statistiques multipoints représentatives des hétérogénéités et un modèle géologique 3D de l'alluvium est généré via l'algorithme snesim.Des suivis neutroniques de l'humidité le long de plusieurs profils caractéristiques des différentes unités sédimentaires associées à ce modèle sont réalisés pour des conditions de flux contrôlées en surface. A partir de simulations numériques 1D, des jeux de paramètres hydrodynamiques permettant de reproduire les humidités mesurées sont déterminés par une approche de type Monte-Carlo. Des densités de probabilité intégrant l'incertitude sur les mesures sont obtenues pour les paramètres de Mualem - van Genuchten décrivant les courbes de rétention et de conductivité hydraulique des sédiments.Une procédure 1D-distribuée est utilisée pour simuler les écoulements non-saturés verticaux au sein de plusieurs réalisations du modèle géologique et pour différents jeux de paramètres hydrodynamiques probables. La recharge diffuse calculée se montre particulièrement sensible au paramètre de pression d'entrée d'air attribué aux dépôts superficiels, siège des principales interactions sol-plante-atmosphère, ainsi qu'aux contrastes verticaux de conductivité hydraulique. / The downstream part of the Komadugu Yobe River is an important recharge area for the Lake Chad Quaternary aquifer. Since the 1980s, cash crop development (e.g. sweet pepper) has led to the doubling (1995-2005) of irrigated surfaces in the vicinity of the river. A modeling approach of vertical water fluxes through the vadose zone (0-8 m) was designed to quantify the related increase in groundwater recharge. The first step, which is the main topic of this PhD thesis, consisted in describing both spatial arrangement and hydrodynamic properties of the sedimentary bodies that make up the alluvium.Boreholes in surficial deposits highlighted sandy to clayey alternations within the whole unsaturated zone; this was interpreted as the result of frequent migrations of the River channel. Spatial correlation between bore logs showed strong similarities with heterogeneities depicted on ground by means of remote sensing data (binarized Landsat 7 image). This data were therefore used to train multiple-point statistics representative of heterogeneities, and a 3D geological model was generated through the snesim algorithm.For each representative sedimentary unit, soil moisture under controlled hydraulic surface conditions was monitored by vertical neutron probe soundings. Using 1D numerical simulations, different data sets of hydrodynamic properties that reproduced moisture measurements were determined by a Monte-Carlo approach. Probability density functions including measurement uncertainties were deduced for the Mualem - van Genuchten parameters which describe both retention and hydraulic conductivity curves.A 1D-distributed procedure was applied for modeling vertical flows in the unsaturated zone within several geological model realizations with different probable sets of hydrodynamics parameters. The simulated diffuse recharge was shown to be particularly sensitive to two main parameters: air-entry pressure linked to superficial deposits, where soil-plant-atmosphere interactions do occur, and vertical hydraulic conductivity contrasts within the alluvium.

Gerenciar riscos é fundamental para que investimentos estejam protegidos de quaisquer fatores que possam modificar um cenário idealizado. Imprevistos não podem ser controlados, mas seus impactos podem ser minimizados se forem tomadas medidas de planejamento considerando diversos cenários da realidade. A indústria mineral se encaixa neste paradigma, pois diversas de suas áreas são estocásticas, desde flutuações econômicas e políticas até fenômenos relativos ao clima e à geologia. Uma destas características de difícil previsão é o volume das mineralizações em um depósito. Um cenário ideal é aquele em que é conhecido o valor esperado da variável de interesse, bem como sua dispersão, com mínimo e máximo definidos. Isto pode ser obtido a partir da combinação dos resultados de estimativa, que resultam em um valor esperado, aliados ao resultado das simulações, em que pode ser obtida a variância entre todos os cenários equiprováveis. Este trabalho propõe uma técnica para quantificar a incerteza dos volumes na modelagem geológica de domínios mineralizados em dois modelos geológicos, interpolado e interpretado, através da transferência da variância obtida nos resultados da simulação, e desta forma criar uma ferramenta de gerenciamento de risco e planejamento a partir dos resultados de incerteza. Para isto foram utilizados os dados de descrição geológica de 168 testemunhos de sondagem de um depósito de cobre, localizado no norte da Bahia. Os resultados mostraram a possibilidade em se utilizar os dados de variância da simulação para quantificar a incerteza em cada domínio do depósito. A partir do volume esperado em determinado modelo, e com os valores da variância da simulação, foi possível identificar uma gama de possibilidades volumétricas. Adicionalmente, a probabilidade de que cada bloco faça parte de um domínio foi calculada, e os volumes dos domínios foram parametrizados para auxiliar na avaliação da incerteza. / Managing risks is essential for investments being safe from any factors that may modify an idealized scenario. Unpredictabilities cannot be controlled, but their impacts can be minimized if planning measures are taken considering various scenarios of reality. The mining industry fits this paradigm, since several of its fields are stochastic, from economic and political fluctuations to phenomena related to climate and geology. One of these characteristics, which are difficult to predict, is the volume of mineralization at the deposit. An ideal scenario is the one in which both the expected value and its dispersion are known, with defined minimum and maximum. This can be achieved with the combination of results from estimates and simulations, the first providing the expected value and the last providing the variance of the variable. This research proposes a technique to quantify the volumetric uncertainty in geological modeling of mineralized domains on two geological models, interpreted and interpolated, by transferring the variance obtained in the simulation results, thus creating a risk and planning management tool from the uncertainty results. For that, we used a geological logging from a database set with 168 drillholes of a copper deposit located north of Bahia state, Brazil. The results showed that it is possible to use the variance from simulation to quantify the uncertainty in each deposit domain. Using the expected volume value in a specific model with the variance values of the simulations, it were able to identify a range of possibilities for the volumetric content of each domain. In addition, the probability of each block being a domain was calculated, resulting in a volume parametrization by probability that can assist in the uncertainty analysis.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-11-29T11:27:18Z No. of bitstreams: 1 Reginaldo Macedônio da Silva_.pdf: 12568015 bytes, checksum: b7f2c89facf89b0186ab816497e38c2a (MD5) / Made available in DSpace on 2018-11-29T11:27:19Z (GMT). No. of bitstreams: 1 Reginaldo Macedônio da Silva_.pdf: 12568015 bytes, checksum: b7f2c89facf89b0186ab816497e38c2a (MD5) Previous issue date: 2014-08-11 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / PROSUP - Programa de Suporte à Pós-Gradução de Instituições de Ensino Particulares / O crescente avanço de novas tecnologias na área das geociências, como o posicionamento por GNSS, o mapeamento por GPR ou a geração de modelos tridimensionais com a técnica LIDAR permite a integração de técnicas de sensoriamento remoto em diferentes aplicações nas geociências. Para isso é necessário experimentar, testar e avaliar cientificamente o potencial de integração dessas diferentes tecnologias, de forma a explorar em sua plenitude os diferentes tipos de dados. A análise, descrição e interpretação de afloramentos são atividades corriqueiras dos trabalhos de campo geológicos. Apesar do avanço tecnológico das últimas décadas, a obtenção de dados quantitativos a partir do uso de instrumentos não se sobrepôs à tradicional forma de aquisição de dados pelos geólogos: a observação da rocha. Dessa forma, o estudo de afloramentos constitui uma fonte indispensável para a obtenção de dados intermediários entre as escalas megascópica (e.g., geologia regional) e microscópica (e.g., amostra), que por sua natureza são dependentes de aquisição por sensores remotos e instrumentos diversos. O principal desafio em pesquisas dessa natureza é integrar dados quantitativos e digitais, obtidos por instrumentos com diferentes princípios de aquisição e integrá-los aos dados qualitativos e analógicos obtidos pela subjetividade da percepção do geocientista. O objetivo deste trabalho foi analisar, testar e validar essa abordagem multidisciplinar para a modelagem de afloramentos considerando um estudo de caso real no Afloramento Morro Papaléo. Para tanto, considerou-se como premissa que o modelo geológico resultante da integração de dados de diferentes naturezas não tivesse erro posicional em ordem de grandeza superior à resolução espacial do sensor com maior limitação de amostragem. A integração de dados segundo procedimentos metodológicos adequados permitiu gerar um Modelo Digital de Afloramento (MDA) que tornou possível visualizar, medir e interpretar com exatidão a geologia a partir de uma representação geológica do objeto de estudo. A validação de campo foi realizada para assegurar que a qualidade da metodologia proposta pode ser utilizada nesse tipo de estudo. Quanto aos dados de subsuperfície, por meio de seções geofísicas, foi possível estabelecer correlações entre os dados obtidos com a técnica LIDAR, o que permitiu integrar dados de superfície e de subsuperfície. Portanto, com o estabelecimento do modelo 3D gerado numa base de dados consistente, calibrada e validada pode-se a qualquer tempo adicionar dados e incrementar o modelo de forma dinâmica. / The increasing advance of new technologies in the field of geosciences, such as GNSS positioning, mapping by GPR or the generation of three dimensional models with the LIDAR technique allows the integration of orbital and non-orbital remote sensing techniques for different applications in geosciences. Thus, it is necessary to experiment, test and scientifically evaluate the potential of integration of these different technologies in order to explore the different types of data. The analysis, description and interpretation of outcrops are daily activities of the geological fieldwork. Despite the technological advances in the last decades, the acquisiton of quantified data from instruments and sensors did not substitute the traditional source of data of the geologists: the observation of the rock. Thus, the study of outcrops is fundamental in the acquisition of intermediate data between the megascopic (e.g. regional geology) and microscopic scales (e.g., sample), quite dependent of acquisition by remote sensors and instruments. The main challenge in this type of research is to integrate quantitative digital data obtained by instruments and sensors based on different principles with qualitative, analogic data, obtained by the subjective perception of the geoscientist. The main purpose of this study was to analyze, test and validate this multidisciplinary approach to the modeling of outcrops considering a real case study in Morro Papaléo Outcrop. For this, it was considered as a premise that the geological model resulting from the integration of different data had not a positional error in an order of magnitude higher than the spatial resolution of the more limited sensor. The data integration using appropriate methodological procedures allowed generate a Digital Outcrop Model (DOM) which made it possible to view, measure and accurately interpret the geology from a 3D geological representation. The field validation was performed to ensure that the quality of the proposed methodology can be used in this type of study. Through geophysical sections was possible to correlate subsurface data with those obtained with the LIDAR technique, allowing data integration of surface and subsurface data. Therefore, with the establishment of the 3D model generated in a consistent database, calibrated and validated, at any time more data can be added to this dynamic model.