Accessibility to consistent subsurface hydrostratigraphic information is crucial for the development of robust groundwater flow and contaminant transport models. However, full three-dimensional understanding of the subsurface geology is often the missing link. Construction of watershed-scale hydrostratigraphic models continues to be limited by the quality and density of borehole data which often lack detailed geologic information. This can become a serious problem where rapid sediment facies changes and intricate sediment architecture occur. This research is motivated by the idea that if we can understand more about the distribution of sediments and structures of complex deposits, we learn more about depositional processes and how they affect the internal geometry of a deposit and the distribution of hydraulic properties. One approach is to study surficial excavations (e.g. sand and gravel pits) that often punctuate shallow aquifers. The purpose of this study is to develop and test a method of integrating high-resolution georeferenced stratigraphic and sedimentologic information from sand and gravel pits as a means to better document sedimentologic data and improve understanding of the depositional environments. The study area is located within the Waterloo Moraine, in southwestern Ontario, and is an unconsolidated shallow aquifer system with a complex internal architecture and sediment heterogeneity. The method involves the integration of high-resolution field data with borehole and geophysical information in a computer-based 3D environment. A total of fourteen virtual sedimentary sections were constructed by georegistering digital photographs within a framework of georeferenced positions collected using a reflectorless total station and GPS. Fourteen sediment facies have been described in the field. These include crudely stratified gravel beds, planar and cross-laminated sandy strata (ripple and dune scales), along with laminated and massive silty and clayey beds. Calculated hydraulic conductivities span over seven orders of magnitude. The analysis of a single excavation has shown contrasting sediment assemblages from one end of the pit to the other, highlighting the complexity of the Waterloo Moraine. The heterogeneous and deformed layers of gravel, sand, and mud may be the product of an ice-contact to ice-proximal environment, whereas the extensive sandy assemblages may reflect an intermediate subaqueous fan region. The results also suggest that the borehole database overestimates the amount of fine-grained material in the study area. Finally, this research demonstrates that it is possible to build in a timely manner a 3D virtual sedimentologic database. New emerging technologies will lead to increased resolution and accuracy, and will help streamline the process even further. The possibility of expanding the 3D geodatabase to other excavations across the region in a timely manner is likely to lead to improved hydrostratigraphic models and, by extension, to more efficient strategies in water resources planning, management and protection.

Made available in DSpace on 2015-03-13T17:08:32Z (GMT). No. of bitstreams: 1 ThalesESJ_DISSERT.pdf: 669387 bytes, checksum: 33a20d208304804215535ed96770330f (MD5) Previous issue date: 2012-04-27 / In this study, the methodological procedures involved in digital imaging of collapsed paleocaves in tufa using GPR are presented. These carbonate deposits occur in the Quixer? region, Cear? State (NE Brazil), on the western border of the Potiguar Basin. Collapsed paleocaves are exposed along a state road, which were selected to this study. We chose a portion of the called Quixer? outcrop for making a photomosaic and caring out a GPR test section to compare and parameterize the karst geometries on the geophysical line. The results were satisfactory and led to the adoption of criteria for the interpretation of others GPR sections acquired in the region of the Quixer? outcrop. Two grids of GPR lines were acquired; the first one was wider and more spaced and guided the location of the second grid, denser and located in the southern part of the outcrop. The radargrams of the second grid reveal satisfactorily the collapsed paleocaves geometries. For each grid has been developed a digital solid model of the Quixer? outcrop. The first model allows the recognition of the general distribution and location of collapsed paleocaves in tufa deposits, while the second more detailed digital model provides not only the 3D individualization of the major paleocaves, but also the estimation of their respective volumes. The digital solid models are presented here as a new frontier in the study of analog outcrops to reservoirs (for groundwater and hydrocarbon), in which the volumetric parameterization and characterization of geological bodies become essential for composing the databases, which together with petrophysical properties information, are used in more realistic computer simulations for sedimentary reservoirs. / Nesse trabalho s?o apresentados os procedimentos metodol?gicos envolvidos no imageamento digital de paleocavernas colapsadas em tufas carbon?ticas que ocorrem na borda oeste da Bacia Potiguar com GPR. Foi mapeada uma ?rea em Quixer? (CE) e selecionado um afloramento em um corte de estrada, denominado de Afloramento Quixer?. Foi escolhida uma por??o deste afloramento para confec??o de um fotomosaico e levantamento de uma se??o-teste com o GPR para a compara??o e parametriza??o das geometrias c?rsticas aflorantes e imageadas na linha geof?sica. Os resultados foram satisfat?rios e permitiram a ado??o de crit?rios para a interpreta??o das paleocavernas colapsadas em outras se??es GPR, levantadas na regi?o do afloramento. Foram adquiridas duas malhas de linhas GPR, a primeira mais ampla e espa?ada norteou a loca??o da segunda, mais adensada, na por??o sul do Afloramento Quixer?. Nos radargramas foram interpretadas e parametrizadas as geometrias das principais paleocavernas colapsadas. Para cada malha foi elaborado um modelo de s?lido digital do Afloramento Quixer?, sendo que o primeiro modelo permitiu o reconhecimento da distribui??o geral das tufas e a localiza??o das paleocavernas colapsadas, enquanto o segundo modelo digital, por ser mais detalhado, possibilitou n?o apenas a individualiza??o 3D das principais paleocavernas, mas tamb?m o c?lculo dos seus respectivos volumes. Os modelos de s?lidos digitais s?o aqui apresentados como uma nova fronteira no estudo de afloramentos an?logos a reservat?rios (h?dricos ou petrol?feros), na qual a parametriza??o e a caracteriza??o volum?trica dos corpos geol?gicos passam a ser fundamental para compor bancos de dados, que conjuntamente com informa??es de propriedades petrof?sicas s?o utilizados em simula??es computacionais mais real?sticas de reservat?rios.

Este projeto teve por objetivo a construção de um modelo hidrogeológico baseado em Elementos Finitos para estudar a variação de nível do aquífero livre em área de afloramento do Sistema Aquífero Guarani. A área é a bacia do Ribeirão da Onça, localizada na região central do Estado de São Paulo. Dados topográficos, hidrológicos e hidrogeológicos da região de interesse foram obtidos principalmente através de mapas, de poços e estações metereológicas próximas e na área de estudo, com o apoio do Centro de Recursos Hídricos e Ecologia Aplicada (CRHEA) da Universidade de São Paulo (USP). Os dados já existentes no Laboratório de Hidráulica Computacional (LHC) da Escola de Engenharia de São Carlos (EESC), bem como os dados coletados no decorrer do trabalho, foram utilizados para definição de suas condições de contorno e calibração do modelo. Estes foram processados e analisados em ferramenta SIG. Assim foram definidos os parâmetros para a construção da malha de elementos finitos dentro do pacote de Simulação de Processos em Aquíferos (SPA), software utilizado para a modelagem numérica desenvolvido no LHC. Foi simulado o fluxo estacionário como condição inicial para a modelagem transiente. Visto as condições de contorno adotadas, o modelo transiente resultou em cálculos satisfatórios de carga hidráulica, considerados os poços de monitoramento existentes na área de estudo e a particular localização de cada um. A ferramenta mostrou bom desempenho e, como sugestão, a continuidade do monitoramento da região se faz necessária para manutenção e melhora das informações a respeito do comportamento da água subterrânea e do SAG como reserva deste importante recurso. / This works presents a hydrogeological model based on finite element to study the variation in level of free aquifer in the outcrop area of the Guarani Aquifer System. The area was the basin of Ribeirão da Onça, located in the central region of São Paulo. Topographic, hydrological and hydrogeological data of the region of interest were obtained mainly through maps, weather stations and wells near and within the study area, with support from the Center for Water Resources and Applied Ecology (CRHEA), University of São Paulo (USP). The data already existing in the Laboratory of Computational Hydraulics (LHC) at the School of Engineering of Sao Carlos (EESC) and the data collected during the study were used to define its boundary conditions and model calibration. These data were processed and analyzed in a GIS tool. Thus were defined the parameters for the construction of the finite element mesh within the package of Process Simulation in Aquifers (SPA), software used for numerical modeling developed at the LHC. Steady flow was simulated as an initial condition for transient modeling. Since the boundary conditions adopted, the transient model resulted in satisfactory hydraulic head calculations, considering the existing monitoring wells in the study area, taking into account the particular location of each. The tool has shown good performance and, as a suggestion, the continued monitoring of the region is necessary for maintenance and improvement of information about the behavior of groundwater and SAG as a store of this important resource.

Störungszonen in den karbonatischen Wechselfolgen des Muschelkalks (Mittlere Trias) sind potenzielle Ziele für hydrothermale Projekte im Oberrheingraben (ORG). Es wurden verschiedene Methoden miteinander kombiniert, um die Permeabilitäts-Strukturen solcher Störungszonen, deren Spannungszustände und lokale Spannungsfelder abzuschätzen. Diese Arbeit kann damit zur Exploration von störungsgebundenen Muschelkalk-Reservoiren im ORG beitragen. Sie vergleicht diese mit einem bereits erfolgreich getesteten (störungsgebundenen) hydrothermalen Reservoir, den Sandsteinen des Buntsandsteins. Um für den Muschelkalk die Charakteristika von Störungszonen zu definieren und die zugehörige Permeabilitätsstruktur abzuschätzen, wurden verschiedene Störungszonentypen (z.B. Abschiebungen, invertierte Störungszonen, Schrägabschiebung) mit unterschiedlichen Maßstäben (Versatz: mittel-skalig 1-10 m, groß-skalig >10 m) detailliert untersucht. Eine Aufschlussanalogstudie zu einer groß-skaligen Störungszone (Schrägabschiebung) in dickbankigen Sandsteinen (Buntsandstein, Untere Trias) wurde zum Vergleich herangezogen. Der besondere Schwerpunkt lag jeweils auf der Charakterisierung von Bruchzone und Störungskern sowie des assoziierten Bruchsystems (Bruchdichte, Öffnungsweitenverteilung, Vernetzungsgrad, vertikale Ausdehnung). Die Daten zeigen, dass Bruchsysteme in eher homogenen Einheiten einen positiven Effekt auf die Reservoir-Permeabilität haben. Sie bieten, vor allem in der Nähe des Störungskerns, potenzielle Fließwege auch über mehrere Schichten und zeigen eine starke Vernetzung zwischen vergleichsweise kurzen Brüchen. Im Gegensatz dazu scheinen störungsgebundene Bruchsysteme in Einheiten mit einer starken mechanischen Schichtung einen geringeren Einfluss auf die Reservoirpermeabilität zu haben. Störungskerne zeigen stellenweise eine signifikante Komplexität, da sie vor allem abdichtende aber stellenweise auch durchlässige Strukturen aufweisen. Groß-skalige Störungszonen (im Reservoir-Maßstab) lassen sich für beide potenzielle Reservoirhorizonte am besten als kombinierte Barriere-Leiter-Systeme beschreiben. Diese Barriere-Leiter-Systeme zeichnen sich durch ein potenziell hydraulisch durchlässiges Bruchsystem in der Bruchzone (und im Buntsandstein zusätzlich in der Übergangszone) sowie einen schwach durchlässigen bis abdichtenden Störungskern aus. Um die Kenntnisse zum lokalen Spannungsfeld in Störungszonen im geschichteten Muschelkalk (Reservoirtiefe: 2.900 m) zu verbessern, wurden mit der Finite-Elemente-Software COMSOL Multiphysics® numerische 3D-Modelle erstellt. Es wurden deutliche Unterschiede des lokalen Spannungsfelds in Abhängigkeit von (1) der Orientierung, (2) dem Einfluss der maximalen Horizontalspannung SH im Spannungsregime, (3) Störungszonen-Maßstab und (4) den Kontrasten der mechanischen Eigenschaften festgestellt. In Spannungsregimen mit starker horizontaler Kompression wurde für Spannungsmagnituden und Versatz eine deutliche Abhängigkeit von der Orientierung der Störungszone festgestellt. Vor allem groß-skalige Störungszonen mit einem 30°-Winkel zu SH scheinen einen SH-induzierten Horizontalversatz innerhalb weicher Störungszoneneinheiten zu begünstigen; in dieser wurden die höchsten Versatzbeträge festgestellt. Die typische Abnahme von Spannungsmagnituden in weicheren Störungszoneneinheiten verringert sich in Richtung von Störungszonen, die senkrecht zu SH streichen. Der Einfluss der mechanischen Schichtung steigt mit zunehmender horizontaler Kompression, was zu einem vertikal heterogenen Spannungsfeld führt. Um Annahmen zu einer möglichen hydraulischen Aktivität einer Störungszone zu treffen, werden für die untersuchten Störungszonen analytische Abschätzungen zu Bewegungs- und Dehnungstendenzen unter Reservoir-Bedingungen präsentiert. Die Ergebnisse zeigen unterschiedliche Spannungszustände der analysierten Störungszonen, die auf das rezente Übergangsregime sowie unterschiedliche Orientierungen der maximalen Horizontalspannungen SH zurückzuführen sind. In dieser Arbeit präsentierte Ergebnisse von Aufschlussanalogstudien helfen dabei, fundierte Annahmen zur Permeabilitätsstruktur von Störungszonen zu treffen und damit vielversprechende Bohrziele im ORG zu definieren. In diesem Zusammenhang konnten sedimentäre Wechselfolgen identifiziert werden, die als potenzielle geothermische Reservoire ausgeschlossen werden können. Die Ergebnisse der numerischen 3D-Modellierungen können dazu beitragen, möglicherweise nötige Stimulationsmaßnahmen im Muschelkalk Reservoir optimal auszulegen. Darüber hinaus bieten die Ergebnisse die Möglichkeit, Einblick in potenzielle Probleme während der Bohrungsherstellung in Muschelkalk-Reservoiren zu bekommen, wie zum Beispiel die Wahrscheinlichkeit eines vertikal heterogenen Spannungsfeldes.

Depuis plusieurs années, le LIDAR est utilisé en géologie pour acquérir la géométrie des affleurements sous forme de nuages de points et de surfaces. L'objectif de cette thèse consiste à développer des techniques visant à automatiser le traitement de ces données et notamment l'interprétation de structures géologiques sur affleurements numériques. Ces travaux s'insèrent dans un projet de recherche plus important financé par ENI qui a pour objectif de concevoir des méthodologies pour intégrer des données d'affleurements aux modèles géologiques. La problématique de cette thèse se focalise sur l'extraction d'objets géologiques (ie, traces de fractures ou de limites stratigraphiques) à partir de modèles numériques 3D d'affleurements. L'idée fondamentale consiste à considérer ces entités géologiques comme des lignes de ravins (ie, des lignes de forte concavité). Ce problème fait référence à la détection de lignes caractéristiques en informatique graphique. Dans un premier temps, nous proposons une méthode reposant sur les propriétés différentielles de troisième ordre de la surface (ie, dérivées de courbures). Un traitement est intégré afin de prendre en compte une connaissance a priori pour n'extraire que les objets orientés selon une direction particulière. Du fait du caractère rugueux et erratique des géométries d'affleurements, plusieurs limites apparaissent et mettent en défaut ce genre d'approche. Ainsi, dans un second temps, nous présentons deux algorithmes alternatifs afin de détecter de manière pertinente les objets géologiques ciblés. Ceux-ci prennent le contre-pied des techniques existantes en s'appuyant sur un marquage de sommets, établi depuis des propriétés différentielles de second ordre, suivi d'une opération de squelettisation. Nous validons, dans une dernière partie, l'ensemble des méthodes développées et proposons diverses applications afin de souligner la généricité des approches. / For a few years now, the LIDAR technology has been employed in geology to capture outcrop geometries as point clouds and surfaces. The objective of this thesis is to develop solutions aiming at processing these data automatically and particularly interpreting geological structures on numerical outcrops. This work is funded by ENI-Agip and fits into a larger project which is devoted to creating methodologies to integrate outcrop data into geological models. The problematic of this thesis focuses on the extraction of geological objects (ie, fractures and stratigraphic limit traces) depicted as polylines from numerical outcrop data. The fundamental idea therefore considers these geological entities as ravine lines (ie, lines with high concavity). This problem belongs to the large domain of feature line detection in computer graphics. We propose an approach based on third-order differential properties of the surface (ie, curvature derivatives). An a priori knowledge is integrated to constrain the detection in order to extract the geological structures oriented in a particular direction.The outcrop rugosity and erratic body geometries however raise several limits of this kind of method. We present two alternative algorithms to detect targeted geological objects in a pertinent way. These algorithms rely on a vertex labeling which is executed according to second-order differential properties and followed by a skeletonization process overcoming traditional approaches of feature detection. We finally present a different context of application than the detection of geological structures to validate the proposed approaches and emphasize their genericity.

Made available in DSpace on 2017-07-21T18:13:50Z (GMT). No. of bitstreams: 1 LucineiJoseMysznskijunior.pdf: 4515058 bytes, checksum: 797466883c2d16669cdd6591abd1131c (MD5) Previous issue date: 2012-03-09 / In this study we investigated the taphonomic and stratigraphic analyses of the basal layers of Sequence B (Neopraghiano / Eoemsiano), Ponta Grossa Formation, with a focus on Curva II outcrop, Ponta Grossa, Paraná, which until then had not been studied under these aspects. The objective is to provide a description and interpretation of the above mentioned outcrop, as well as the inclusion of its layers in stratigraphic framework of the sequence. In order to obtain more accurate data, the methodology used to collect data was of taphonomic high-resolution. The fauna here considered is a typical representative of the Malvinokaffric Realm and occurs distinctly along the Curva II outcrop. Three different taphocenosis representing different sedimentary environments have been identified. The data obtained in this study were integrated into the areas of occurrence of fossiliferous outcrops adjacent to Curva II. A combined analysis of the taphonomic, paleontological and stratigraphic aspects, followed by a reinterpretation of the outcrops in northeastern urban area of Ponta Grossa, inserts the Curva II outcrop above sections of the UEPG Campus, as well as Francelina I, II and III and below sections of Curva I and Franco da Rocha, which are representatives of a transgressive process, in a situation of sedimentary retrogradation which occurred in the passage Neopraghiano/Eoemsiano in the Ponta Grossa Formation, filling, thus, a gap in the stratigraphic sequence of the base of sequence B. / Na presente pesquisa buscou-se a análise estratigráfica e tafonômica das camadas basais da Sequência B (Neopraguiano/Eoemsiano), Formação Ponta Grossa, com enfoque no afloramento Curva II, Ponta Grossa, Paraná, que até então não havia sido estudado sob estes aspectos. Objetivou-se a descrição e interpretação do afloramento citado bem como a inserção de suas camadas no arcabouço estratigráfico de sequências. Com o intuito de se obter dados mais precisos, utilizou-se metodologia de coleta de alta resolução tafonômica. A fauna aqui analisada é representante típica do Domínio Malvinocáfrico e ocorre distintamente ao longo do afloramento Curva II tendo sido identificadas três diferentes tafocenoses que representam distintos ambientes de sedimentação. Os dados obtidos nesta pesquisa foram integrados aos de áreas de ocorrência fossilífera adjacentes ao afloramento Curva II. Com uma análise conjunta entre os aspectos tafonômicos, paleontológicos e estratigráficos e após uma reinterpretação dos afloramentos da região nordeste do perímetro urbano de Ponta Grossa, insere-se o afloramento Curva II acima das seções Campus UEPG e Francelina I, II e III e abaixo das seções Curva I e Franco da Rocha, sendo representantes de um processo transgressivo, em situação de retrogradação sedimentar ocorrida na passagem Neo-praguiano/Eo-emsiano da Formação Ponta Grossa, preenchendo, desta maneira, uma lacuna na coluna estratigráfica de sequências local da base da Sequência B.

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.

Submitted by Nara Lays Domingues Viana Oliveira (naradv) on 2015-07-15T18:16:55Z No. of bitstreams: 1 ROBSON.pdf: 2705073 bytes, checksum: d6eefccd3ecb288572c9262f7dc4079a (MD5) / Made available in DSpace on 2015-07-15T18:16:55Z (GMT). No. of bitstreams: 1 ROBSON.pdf: 2705073 bytes, checksum: d6eefccd3ecb288572c9262f7dc4079a (MD5) Previous issue date: 2014 / PROCERGS - Companhia de Processamento Dados do Estado Rio Grande Sul / A coleta de dados espaciais tem sido intensamente empregada na área geológica, através da técnica de LIDAR (Light Detection and Ranging). Este tipo de sensoriamento digital remoto de alta resolução e precisão, resulta em modelos digitais 3D que permitem uma análise mais detalhada e quantitativa de estruturas heterôgeneas, como afloramentos. Um dos estudos realizados pelos geólogos são análises sobre a geometria da formação de rochas, onde a informação de orientação de um plano inclinado é um indicativo para a compreensão global da estrutura. Este trabalho propõe a utilização da técnica de Análise de Componentes Principais (PCA) para calcular e detectar automaticamente todos os planos em uma nuvem de pontos. Uma ferramenta foi construída para implementar a visualização do modelo digital e apurar os melhores planos. Um estudo foi realizado a fim de validar as informações encontradas pelo método proposto e dados medidos em campo. / The use of LIDAR (Light Detection and Ranging) systems for gathering spatial data has been extensively used in geological studies. This type of digital remote sensing delivers high resolution and accuracy, resulting in 3D digital models which allow a more detailed and quantitative analysis of heterogeneous structures, as outcrops. One of the studies is based on analysis of the forming rocks geometry. The orientation of a slope plane is an indication for the overall undestanding of the structure. This work proposes a new method to automatically compute and detect all possible planes in a point cloud, based on Principal Component Analysis (PCA) technique. A software tool was constructed to implement the digital model visualization and compute the best planes. A study was conducted to compare and validate the results of the method and the field data collected.

The Cutler Formation is composed of thick, arkosic, alluvial conglomerate, sandstone, and mudstone shed southwestward from the Uncompahgre Uplift into the Paradox Basin. More basin-ward the Cutler is recognized as a group consisting of differentiable formations. Discrete formations historically have not been distinguished near the uplift, but this study identified several separate successions in the Richardson Amphitheater. Research at the Richardson Amphitheater, ~12 km southwest of the uplift and ~30 km northeast of Moab, Utah, led to a systematic subdivision of the Permian Cutler Formation proximal to the uplift. Likely driven by channel cutting and migration across the alluvial fan, six 10-20 m thick successions are partially exposed. The dominant observed facies are basal conglomerate and channel-fill trough cross-stratified sandstone overlain by finer-grained distal sheetflood and frequently pedogenically altered sandstone. Down-warping of identified successions and the presence of additional sands within the area of flexure suggest that localized salt withdrawal created a sediment depocenter in the Richardson Amphitheater, ~6 km northwest of the Onion Creek salt diapir. The identified salt withdrawal feature is more proximal to the Uncompahgre Uplift than any of the major documented salt structures in the area and was not previously documented. Six measured stratigraphic sections and hundreds of high-precision differential GPS data points outlining major lateral erosional surfaces form the basis for interpretation. Five mapped erosional surfaces (bounding surfaces based upon differential GPS point interpolation) are laterally extensive within the approximately one square kilometer study area, and as such, represent stratigraphically significant surfaces. Within the generated structural geocellular model, stratigraphic data from measured sections informed facies modeling between major surfaces. This outcrop model may serve as an analogue for subsurface systems deposited in similar settings.

The Cretaceous Mowry Shale is an organic-rich, siliceous marine shale, and as such is a known source rock in the Western United States. Studies have documented that total organic carbon (TOC) in the Wind River Basin, Wyoming increases to the southeast. These studies cover large areas with limited sample sets. In this study, over 250 samples were collected near Lander, Wyoming to address spatial heterogeneity of TOC within the Mowry Shale at a much finer scale than previously examined. Samples were collected along five vertical sections at three localities, and following correlation of the vertical sections, which was strongly aided by the presence of regional bentonite horizons, samples were collected laterally from the same unit at regular 25-foot intervals. These samples were analyzed using pyrolysis and x-ray diffraction techniques. Average TOC values are fairly consistent within the study area (1.65%, with a range of 2.10% to 1.15%). Average Tmax values for vertical and lateral samples is 433 °C with a standard deviation of 7.25 °C suggesting immature to very early oil window thermal maturity. Kerogen types are determined to be dominantly type III, suggesting a dominance of terrestrial input, becoming slightly more mixed type II/III to the southeast. Redox-sensitive trace metals such as uranium, thorium, vanadium, chromium, cobalt, and molybdenum values all suggest a slightly oxygenated sediment water interface during time of deposition. These pyrolysis and trace metal data suggest that the study area was in a prograding proximal marine/prodeltaic depositional environment during Upper Mowry time with influences from higher energy bottom flows. Lateral homogeneity of strata and the low variability in geochemical character across the study area suggest that the local basin in the study area was not segmented by structural or oceanographic conditions. While efforts were made to collect unaltered outcrop samples (digging back into what appeared to be unfractured, unaltered rock), alteration or weathering of organic material is a concern for source rock evaluation of near-surface outcrops. In order to address this concern, a 5-foot-deep trench was dug back into the outcrop at the target horizon in one locality. Samples were taken at regular three-inch intervals from this trench as it was excavated to determine the effect of weathering on TOC in the study area. Based on pyrolysis results, TOC was affected by weathering only along fracture sets (several samples intersected fractures in the shallow subsurface) and did not appreciably increase from the surface to a depth of five feet. Due to the impermeable nature of shale rock, decreases of TOC due to weathering appear to be limited to the immediate surface of samples and along fracture sets.