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Evaluation de la variabilité spatiale des paramètres géotechnique du sol à partir de mesures géophysiques : application à la plaine alluviale de Nahr-Beyrouth (Liban) / Evaluation of the spatial variability of geotechnical parameters of soil from geophysical measurements : application to the alluvial plain of Nahr Beirut (Lebanon)Salloum, Nancy 30 April 2015 (has links)
La variabilité spatiale des formations géologiques rend difficile la détermination des paramètres géotechniques nécessaires pour l'évaluation des aléas naturels (sismiques et gravitaires). Les méthodes d'imagerie géophysique, non-destructives et rapides, sont de plus en plus utilisées pour la reconnaissance de telles structures hétérogènes. Une campagne d'essais géophysiques et géotechniques a été réalisée dans la plaine alluviale de Beyrouth (Liban), ville soumise à un fort risque sismique, en vue de caractériser la variabilité des couches alluviales. Les résultats combinés ont permis de caractériser la structure 3D du site et de détecter la présence d'une couche d'argile molle, peu profonde et d'épaisseur variable. Cette couche de faible compacité, qui a rendu complexe l'interprétation des courbes de dispersion des ondes de surface, a une influence importante sur la réponse sismique du site. Les incertitudes reliées à la variabilité spatiale des propriétés géotechnique (N60) et géophysiques (Vs, ρ) ont pu être quantifiées au sein des couches rencontrées et les fonctions de distribution de ces paramètres ont été déterminées dans chaque couche à partir de ces essais, à la fois verticalement et horizontalement. Les valeurs de distance d'autocorrélation verticale (Vs, N60) et horizontale (ρ) obtenues ainsi que les valeurs de coefficient de variation se situent dans la gamme de valeurs trouvées dans la littérature. La réponse dynamique (amplification spectrale) de la plaine alluviale de Beyrouth a été simulée avec des modèles probabilistes unidimensionnels, et l'effet des trois paramètres statistiques (loi d'autocorrélation, distance d'autocorrélation et coefficient de variation) décrivant les variabilités des propriétés élastiques du sol (Vs) a été quantifié. Pour obtenir des réponses sismiques réalistes, un critère de sélection des profils Vs générés de façon probabiliste a été introduit afin de ne retenir que les profils compatibles (dans une gamme d'incertitude) avec la courbe de dispersion établie. Les modélisations probabilistes ont montré des différences significatives par rapport aux modélisations déterministes. Le principal paramètre probabiliste contrôlant l'amplification spectrale est le coefficient de variation, suivi de la distance d'autocorrélation, alors que le type de loi a peu d'influence. Enfin, nous avons vu que l'activité humaine peut avoir une influence significative sur l'application des méthodes géophysiques en site urbain. La compréhension d'un milieu complexe dans ce contexte nécessite de combiner toutes les méthodes géotechniques et géophysiques d'investigation afin d'obtenir un modèle robuste 2D/3D de la structure du sol / The spatial variability of geological formations makes it difficult to determine the geotechnical parameters necessary for the evaluation of natural hazards (seismic and gravity). The geophysical imaging methods, non-destructive and fast, are now increasingly used for heterogeneous structures of sub-surface recognition. Geophysical and geotechnical tests were carried out in the alluvial plain of Beirut (Lebanon), city with high seismic risk, to characterize the variability in the alluvial layers. Analyses of these tests were used to characterize the 3D structure of the site and to detect the presence of a shallow soft clay layer of variable thickness. This layer of low compactness, which made the interpretation of dispersion curves of surface waves complex, could be of prime importance for seismic response of the site. Using all the collected data, the uncertainties related to the spatial variability of geotechnical (N60) and geophysical (Vs, ρ) properties of soil were quantified in the layers encountered and the distribution functions of these parameters were determined in each layer, in both directions (vertical and horizontal). The autocorrelation distance in the vertical (Vs, N60) and horizontal (ρ) directions and the coefficient of variation are within the range of values founded in the literature. The dynamic response (spectral amplification) of the alluvial plain of Beirut was modeled by one dimensional probabilistic model and we quantified the effect of the three statistical parameters (autocorrelation function, autocorrelation distance and coefficient of variation) describing the elastic variability properties of soil (Vs). To obtain realistic seismic responses, we proposed a probabilistic (Vs) profile selection criteria in order to retain only compatible profiles (in a range of uncertainty) with the obtained dispersion curve. Probabilistic modeling showed significant differences from the deterministic modeling. It appeared that the main factor controlling probabilistic spectral amplification is the coefficient of variation (COVVs) followed by the autocorrelation distance, while the type of autocorrelation function has little influence. Finally, Human activity was also found to have a significant influence on the application of geophysical prospecting at this urban site. This case illustrates the need of combining investigation methods in order to understand the geophysical measurements in a complex medium and to reach a robust 2D/3D model.
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Analýza průběhu podpovrchových struktur v reprezentativních řezech výzkumných povodí / Analysis of the subsurface struckutes location in representative transections of the research catchmentsDUBEC, Štěpán January 2014 (has links)
This theses is focused on the description of subsurface in the area of interest - Kopaninský and Jenínský stream catchment - and consequently thy most accurate interpretation depth of impermeable bedrock. Geophysical multicable metod (ERT - electrical resistivity tomography") was selected for field measurements. This method of geophysical survey provides the information on subsurface structures, verifies hypotheses and brings new information on the lithological and structural conditions below the surface. ERT measurements were performed automatically by geoelektrical ARES device in combination with inteligent electrodes. The data obtained by field measurements were plotter in the form of resistive sections (using ReS2DInv software) which were used for the later interpretation. The given results determine the depth and process of impermeable bedrock which are important for more accurate data inputs like for modeling rainfall-runoff processes especially in the field of calibration and validation of each adjustment of models as well as for the next other hydrogical analyzes and studies carried out in the research projects. The purpose of this work is to determine the depth of impermeable bedrock and could serve as a data input for MIKE SHE hydrological modeling.
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Electrical resistivity measurements of mechanically stabilized earth retaining wall backfillSnapp, Michael Andrew January 1900 (has links)
Master of Science / Department of Civil Engineering / Stacey Kulesza / In Kansas, mechanically stabilized earth (MSE) retaining walls are typically backfilled with coarse aggregate. Current backfill material testing procedures used by the Kansas Department of Transportation (KDOT) utilize on-site observations for construction quality assurance and the American Association of State Highway and Transportation Officials standard T 288-12 (“Standard Method of Test for Determining Minimum Laboratory Soil Resistivity”). AASHTO T 288-12 is designed to test a soil sample’s electrical resistivity (ER) that correlates to its corrosion potential. However, the test, based on material passing through a No. 10 sieve, is inappropriate for coarse aggregate typically used by KDOT as the aggregate will be retained on a No. 10 sieve and potentially leads to over-conservative designs. However, ER imaging provides a two-dimensional (2D) profile of bulk ER of backfill material, thereby yielding more information regarding backfill uniformity compared to traditional sampling. The objective of this study was to characterize bulk ER of in-place MSE wall backfill aggregate.
In this study, MSE walls selected by KDOT were tested using ER imaging during construction to determine bulk ER of the backfill. Variations within backfill ER may be a result of varying aggregate material, inclusions of fines, thoroughness of compaction, and the presence of water. ER imaging was used on five walls: four MSE walls and one gravity retaining wall that contained no reinforcement. One MSE wall contained metal reinforcement, while the other four walls contained geosynthetic. The ER imaging field method produced a 2D profile that depicted ER uniformity for bulk analysis. A post processing algorithm was generated to remove the subjective nature of the ER imaging results. The program determines the bulk ER based upon the ER imaging results. These results indicate that the laboratory analysis of AASHTO T 288-12 under-estimates the bulk ER of in-situ backfill material. Identification of a material’s bulk ER will help characterize the ER of aggregates in a complementary KDOT project. Results of this study will be used to recommend an in-situ test method for aggregate used by KDOT.
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Evidências do lineamento transbrasiliano na região nordeste de Mato Grosso do Sul : aspectos lito-estruturais e aerogeofísicos (magnetometria e gravimetria)Campos, Francisco Abel Pompeu de 01 July 2015 (has links)
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Previous issue date: 2015-07-01 / CAPES / O Lineamento Transbrasiliano é a mais importante zona de falha de escala continental reconhecida no Brasil, transecta a plataforma sul-americana em uma direção NE-SW, influenciando nas diversas compartimentações desta plataforma desde o brasiliano, entre elas relaciona-se a evolução e estruturação da bacia do Paraná. Há pelo menos três reativações reconhecidas desde o Devoniano, a última relacionada a abertura do Atlântico Sul no Cretáceo com geração do magmatismo Serra Geral associado à Bacia do Paraná. Interpretações qualitativas de lineamentos magnéticos, sugerem descontinuidades magnéticas relacionadas ao trend principal do Lineamento Transbrasiliano sob a Bacia do Paraná na Região nordeste do estado de Mato Grosso do Sul. Os resultados da aplicação de filtragem combinada - Matched Filtering indica três níveis magnetométricos com suas respectivas profundidades, onde sua continuidade vertical chega a pelo menos 25 quilômetros. Domínios de alta frequência podem ser relacionados ao magmatismo no nível mais raso desta filtragem na porção leste da área de estudos, não havendo indicação da presença do mesmo na porção central e oeste da área. Associa-se a ausência do magmatismo Serra Geral nesta região a falhamentos de natureza extensional característico de um padrão do tipo horst, com posterior caráter erosivo recorrente às atividades hidrográficas. Um sistema oblíquo intersecta as descontinuidades principais deslocando-os num rearranjo estrutural dos blocos evidenciados nos dados geofísicos e em controle de campo, com sistemas de juntas impostas ao magmatismo de idade cretácea. / The Transbrasiliano Lineament is the most important continental scale fault zone recognized in Brazil,
crosscuts the South American platform in a NE-SW direction, influencing several domains in this platform
since the brasiliano, including the Paraná Basin development and structuring. There are at least three
reactivations recognized since the Devonian, the latter related to the opening of the South Atlantic in
Cretaceous with generation of the Serra Geral magmatism associated with the Paraná Basin. Qualitative
interpretations of magnetic lineaments suggest magnetic discontinuity related to the main trend of the
Transbrasiliano Lineament concealed by Paraná Basin in the northeastern of Mato Grosso do Sul state. The results of the Matched Filtering application shows three magnetometric levels with their respective depths where its vertical continuity reaches at least 25 km. High-frequency fields can be related to the magmatism in the shallow level of this filtering in the eastern portion of the study area, with no indication of the presence in the central and western portion of the area. Is associated with absence of the Serra Geral magmatism in this region faults characteristic of extensional nature in a standard horst type, with subsequent recurring erosive character of river activities. An oblique system intersects the main discontinuities moving them in a structural rearrangement of the blocks evidenced in the geophysical data and field control, with joints imposed on magmatism with cretaceous age.
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Avaliação de aspectos geológicos e geotécnicos na implantação do aterro sanitário de São Carlos - SP, com o auxílio da geofísica / Evaluation of geological and geotechnical aspects in the implementation of the landfill of São Carlos-SP, with the help of geophysicsLucas Schettini 08 August 2016 (has links)
A caracterização geológica e geotécnica dos locais de implantação de aterros sanitários é fundamental, tanto para fornecer subsídios adequados ao projeto de instalação das células de deposição dos resíduos sólidos urbanos (RSU), quanto para que se conheçam as características da área antes de ser modificada pela obra. Neste sentido, o presente trabalho visou mostrar a contribuição que a geofísica, com o uso da técnica da eletrorresistividade e do potencial espontâneo, associado a informações de investigação geotécnica direta pode dar para o estabelecimento de um background da área de instalação do aterro sanitário da cidade de São Carlos-SP. Foram realizados 7 caminhamentos elétricos (CE) com o arranjo dipolo-dipolo com eletrodos espaçados de 10 metros e três sondagens elétricas verticais (SEV), utilizando o arranjo Schlumberger, com profundidade de investigação de até 100 metros. Para processamento dos modelos bidimensionais dos CE utilizou-se o programa RES2DINV, e enquanto que para as SEV foi utilizado o modelo unidimensional. A interpretação dos modelos geoelétricos foi aperfeiçoada pela confrontação com informações geológico-geotécnicas prévias da área, obtidas nos estudos de impacto ambiental (EIA/RIMA) e resultados de sondagens de simples reconhecimento (SPT), realizadas na fase de estudo para implantação do aterro sanitário. Com isso foi possível definir com clareza a profundidade do topo rochoso e das zonas de maior umidade nos CE e SEV. O conjunto de seções de CE foi georeferenciada com o auxílio de GPS de precisão, o que permitiu o tratamento espacial das informações e o estabelecimento dos mapas da superfície do topo rochoso, das zonas de fluxo de água subterrânea e da espessura dos materiais inconsolidados. O conjunto de informações obtido permitiu identificar locais possíveis para a instalação futura de poços de monitoramento, assim como os dados geoelétricos das várias camadas servirá como padrão para identificar eventuais contaminações do solo ou da água subterrânea no futuro. A identificação da presença do topo rochoso em pequena profundidade, em algumas áreas do aterro, permite o melhor planejamento das escavações para instalação das células de deposição do RSU. / The geological and geotechnical characterization of landfill implantation areas is crucial; even to provide appropriate subsidies of urban solid residues (USR) installation project of deposition cells and for knowing the characteristics of the area before being modified by the work. In this sense, the present work aimed to show the contribution that the geophysics, with the use of electrical resistivity technique and the spontaneous potential, associated with direct geotechnical investigation information can give to the establishment of a background of landfill installation area from São Carlos-SP city. Were performed 7 electrical imaging (EI) with the dipole-dipole array with electrodes spaced by 10 meters and three vertical electrical sounding (VES), using the Schlumberger array with depth research up to 100 meters. For processing of two-dimensional models of the EI was used the RES2DINV program and while for the vertical electrical sounding (VES)-was used one-dimensional model. Interpretation of geoelectric models was enhanced by the confrontation with geological and geotechnical information of prior area, obtained in the environmental impact assessment (EIA) and results of a simple reconnaissance probes, performed in the study phase for the landfill implementation. It was possible to clearly define the depth of the bedrock and the higher humidity areas in the EI and VES. The set of sections electrical Imaging (EI) was georeferenced with the aid of GPS accuracy that allowed the spatial treatment of Information and the setting maps of the bedrock surface, the groundwater flow zones and the thickness of the unconsolidated materials. The obtained set of information enabling identification of possible locations for the wells future monitoring installation, as well as the geoelectrical data from several layers will be use as a standard to identify possible contamination of the soil or groundwater in the future. The identification of bedrock presence in small depth, in some areas of landfill, allows better planning of excavation for installation of MSW deposition cells.
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Ritmos de acasalamento e habitat de recrutamento do caranguejo-uçá (Ucides Cordatus) e suas implicações para a gestão em manguezais de caravelas, BASchmidt, Anders Jensen January 2012 (has links)
Tese(doutorado) - Universidade Federal do Rio Grande, Programa de Pós–Graduação em Oceanografia Biológica, Instituto de Oceanografia, 2012. / Submitted by Cristiane Gomides (cristiane_gomides@hotmail.com) on 2013-11-18T14:07:49Z
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Previous issue date: 2012 / O caranguejo-uçá, Ucides cordatus, é uma espécie chave para o manguezal, tem grande importância socioeconômica e seus estoques vêm sendo reduzidos por mortalidades em massa. Para subsidiar a gestão deste recurso pesqueiro, este estudo objetivou gerar conhecimento sobre sua reprodução e recrutamento. As ocorrências das chamadas “andadas” reprodutivas foram registradas de 2006 a 2011, sendo que, em 2008 e 2010, a abundância e comportamento de U. cordatus foram monitorados. Um total de 1441 caranguejos foi observado, dos quais 80% exploravam tocas. Em torno de 90% dos caranguejos que estavam explorando tocas eram machos a procura de parceiras. Foram registrados 78 caranguejos escalando árvores, sendo 78%
deles, fêmeas realizando extrusão de ovos. Estes movimentos foram utilizados para análise crítica de classificações unificadoras de movimento animal e concluiu-se que é ainda necessária uma nomenclatura que permita uma classificação sem ambiguidades e um agrupamento coerente de movimentos de diferentes taxa, de acordo com suas causas evolutivas. Foi constatado que as andadas podem ocorrer de dia e de noite e que o ritmo de procura de parceiros é ligado ao “ciclo de desigualdade de maré de sizígia”. Em sincronia com este ciclo, as andadas variaram entre lua cheia ou nova, dependendo de qual fase apresentava a maior amplitude de maré. A causa evolutiva mais provável da andada é permitir a maior sobrevivência das larvas através da liberação sincronizada com a maré de maior amplitude, um mês depois. Este
conhecimento facilitará a determinação de períodos de defeso, reduzindo conflitos entre os coletores e o órgão gestor. Para estudar o recrutamento, juvenis foram amostrados mensalmente de Abril/08 a Maio/09. Dos 474 recrutas encontrados, 96% estavam associados a tocas de coespecíficos, indicando facilitação ecológica. O recrutamento foi maior em zonas intermediárias do gradiente ambiental, com altura de inundação estimada de 18,5 cm, evitando a alta predação das zonas mais inundadas e o estresse
físico-químico das menos inundadas. Amostragens em outras 6 áreas, com diferentes padrões de zonação, também revelaram maior recrutamento em zonas de manguezal arbóreo menos inundadas, próximas à transição para terra-firme. Ressalta-se, portanto, a importância da conservação e da nomenclatura adequada desta zona de transição, sugerindo-se que esta seja definida tendo como critério a estrutura herbácea de sua vegetação e não medições de salinidade e inundação, que podem variar espaço-temporalmente e, portanto, serem subjetivas. O conhecimento sobre recrutamento habitat específico poderá indicar se ações de repovoamento são realmente necessárias para a recuperação de estoques de U. cordatus afetados por
mortalidades em massa. / The land crab, Ucides cordatus, is a keystone species for the mangrove, has an important socioeconomic role and their stocks have been reduced by mass mortalities. To support the management of this fisheries resource, the aim of the study was produce knowledge about its reproduction and recruitment. The occurrences of the so-called reproductive andadas (= “walk” in Portuguese), were recorded from 2006 to 2011. In 2008 and 2010, the abundance and behaviour of U. cordatus were also monitored. A total of 1441 crabs were observed, 80% exploring burrows. About 90% of exploring crabs were males searching for mates. We recorded 78 crabs climbing on trees and 78% of them were females extruding eggs. We used these movements for the critical assessment of unifying animal movement classifications. We conclude that a nomenclature allowing an unambiguous classification and a coherent grouping of movements across different taxa, according to their ultimate causes is still lacking. We found that andada occurred during the day and night and that the rhythm of mate searching was linked to the “syzygy tide inequality cycle” (STIC). In sync with this cycle, andada shifted between new and full moon, depending upon which moon phase had the higher amplitude tides. The likely ultimate cause of andada is increased larval survival after synchronous release at highest amplitude spring tides one month later. This knowledge will support the establishment of capture bans and reduce conflicts between fishers and regulatory agencies. To study the recruitment, juveniles were sampled monthly from April 2008 to May 2009. Of the 474 recruits found, 96% were associated with burrows of conspecifics, indicating ecological facilitation. Recruitment was higher in intermediate zones of the environmental gradient, with 18.5 cm of estimated flood height, avoiding high predation at the most inundated zone and the physical-chemical stress at the less flooded zone. Sampling in other 6 areas, with different zonation patterns, also showed higher recruitment in intermediate zones of arboreous mangrove near the transition to hinterland. Therefore it was emphasized the importance of conservation and of a proper nomenclature of this transition zone. It is suggested that the transition zone must be defined based on the herbaceous structure of its vegetation rather than measurements of salinity and inundation, which can vary in space and time and therefore be subjective. Knowledge about habitat-specific recruitment could indicate whether stock enhancement actions are really necessary for the recovery of U. cordatus stocks affected by mass mortalities.
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Análise do comportamento dos perfis de raio Gama, potencial espontâneo e eletroresistividade para determinação das zonas aquíferos em poços tubularesBento, Fabíola Tavares 29 November 2006 (has links)
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Previous issue date: 2006-11-29 / Geophysical approaches are used for map and identify structures (fractures and for layers aquifers optimizing the water wells projects elaboration. Among the diverse existing approaches, to resistivity electric, the range radiation emission and the potential spontaneos of the rocky formations are utilized in the determination of the filter sections of water wells in areas you will consolidate. This researches had for objective perform comparative studies of the lines of the geophysical profiles of resistivity eletrical, spontaneous potential and rays range with the main purpose of research to cause that justified the fact of that, in practically all the profile geophysical that utilize these three approaches, there are operative unknown factors that chewed the line of the geophysical profile, of way such that the configuration of this draw, results expected, having like base the theoretical conceptualization. They were utilized samples of components and fluid, the which were analyzed by difratometry of rays x and the results obtained verified it influences of the fluid utilized in the drilling of wells as regards the behavior of the geophysical profiles of electricity, spontaneous potential and rays range. / Métodos geofísicos são comumente usados para mapear e identificar zonas aquíferas, otimizando a elaboração de projetos de poços tubulares, que tem como escopo a explotação de água subterrânea. Dentre os diversos métodos existentes, a resistividade elétrica, a radiometria e o potencial eletroquímico das formações rochosas são classicamente utilizados na determinação das seções filtrantes de poços tubulares semi-artesianos. Esta pesquisa teve por objetivo efetuar estudos comparativos dos traços dos perfis geofísicos de resistividade, potencial espontâneo e raios gama, com o escopo principal de pesquisar a(s) causa(s) que justificasse(m) o fato de que, em praticamente todas as perfilagens geofísicas que utilizam estes três métodos, há fatores desconhecidos operantes que mascaram o traço do perfil geofísico, de maneira tal que a configuração deste traço, representando as características litológicas atravessadas, diferem dos resultados esperados, tendo como base a conceituação teórica. Foram utilizadas amostragens de componentes e fluidos, os quais foram analisados por difratometria de raios X e os resultados obtidos comprovaram a influência do fluido utilizado na perfuração de poços no comportamento dos perfis geofísicos de eletroresistividade e potencial espontâneo.
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Análise multivariada de dados aerogamaespectrométricos, aeromagnéticos e sensoriamento remoto como auxiliar na prospecção de minerais metálicos na região da Bacia do Camaquã-RS / Multivariate analysis applied to airborne geophysical and remote sensing data as auxiliary tools in the metalic minerals prospection in the Camaquã Basin-RS, BrazilRoberto Paulo Zanon dos Santos 19 March 2014 (has links)
O escudo Sul-riograndense tem sua importância econômica ligada às várias mineralizações de metais base e ouro como as áreas de Camaquã, Caçapava do Sul, Lavras do Sul e São Sepé. A região é objeto de estudos geológicos desde muito tempo e vários trabalhos já foram publicados a respeito, porém todos estes mostram grande complexidade tanto quanto à origem e evolução do escudo como para as ocorrências minerais nela presentes. O presente estudo utilizou um conjunto de análises multivariadas para dados aerogeofísicos e sensoriamento remoto em parte do Escudo do Rio Grande do Sul para verificar a contribuição destas técnicas para a otimização de recursos tanto financeiros quanto de tempo na execução dos projetos de pesquisa mineral naquela região. Os resultados mostraram que o uso destas técnicas contribui para a discriminação de grupos relacionados às litologias descritas para a área de pesquisa de forma muito mais clara que o uso das metodologias de forma individualizada. Embora não tenha revelado as assinaturas das ocorrências minerais pode ser utilizada para a discriminação destas dentro dos grupos formados pelas análises. / The Rio Grande do Sul Shield has its economic importance connected to the diverse gold and base metals mineralization that occurs in that area, such as Camaqua Basin, Cacapava, Lavras do Sul and São Sepé granitite intrusions. The region has been the subject of geological studies for a long time and several papers have been published about it, but they show great complexity for both the origin and evolution of the Shield and the mineral occurrences in it. The present study used a set of multivariate analysis for airborne geophysics and remote sensing data in part of the Rio Grande do Sul Shield, to verify the contribution of these techniques for the optimization of time and financial resources for the implementation of projects of mineral exploration. The results confirm that their use contribute to the discrimination of groups related to the described lithology in the area in a more clearly way that using these methodologies individually. Although the signatures of mineral occurrences have not been revealed, they can be used for their discrimination, based on the groups resultant from the analysis.
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Caracterização litológica e identificação de alvos exploratórios na região de Flor da Serra, Província Aurífera Alta Floresta (MT), utilizando dados magnéticos e geoelétricos / Lithologic characterization and identification of exploration targets in the region Flor da Serra, Alta Floresta Gold Province (T), using magnetic and geoeletricAgnoletto, Ethiane, 1988 23 August 2018 (has links)
Orientadores: Emilson Pereira Leite, Antônio João Paes de Barros / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-23T19:02:09Z (GMT). No. of bitstreams: 1
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Previous issue date: 2013 / Resumo: A região garimpeira de Flor da Serra situa-se na porção Leste da Província Aurífera Alta Floresta, Norte do Mato Grosso, inserida no contexto geológico da porção Centro-Sul do Cráton Amazônico, constituída por suítes plutono-vulcânicas de idade paleoproterozóica e coberturas sedimentares associadas. Várias ocorrências de ouro estão dispostas em grandes zonas de descontinuidade crustal que delimitam terrenos geocronológicos e geológicos. O expressivo adensamento de corpos filoneanos e o histórico de produção destaca essa região de expressivo potencial exploratório. Neste contexto, o trabalho teve por objetivo a identificação de novos alvos exploratórios por meio da análise de dados geofísicos, descrição de testemunhos de sondagem e mapeamento de cavas garimpeiras. A integração desses dados contribuiu em especial à evolução do conhecimento geológico da região Flor da Serra, e também de maneira geral para o setor leste da PAAF. A área de estudo está inserida na Suíte Intrusiva Flor da Serra, que é constituída eminentemente por gabros, dioritos a monzogabros, entretanto com o mapeamento de cavas garimpeiras e descrição de furos de sondagem, verificou-se a existência de quatro unidades geológicas principais: (i) Granitóides do Embasamento de composição tonalítica a granodiorítica com associação de magnetita + granada, intrudidos por rochas da (ii) Unidade Granodiorítica a Tonalítica de mesma composição. Essa unidade é truncada por (iii) Diques Máficos a Intermediários e localmente há presença de (iv) Rochas Cataclásticas a Miloníticas. Os litotipos foram variavelmente afetados por sete tipos de alteração hidrotermal (ordem temporal): (i) alteração potássica intensa, (ii) silicificação pervasiva, (iii) carbonatação, (iv) alteração com muscovita, (v) propilitização mais pontual, (vi) alteração Quartzo-Sericita-Pirita (QSP) com substituição total da rocha e, (vii) vênulas de calcita tardias. Foram realizados levantamentos geofísicos utilizando métodos geoelétricos (Polarização Induzida/Resistividade - IP/RES) e magnetometria em escala de depósito. Valores anômalos de cargabilidade e resistividade obtidos após aplicação de um algoritmo de inversão com vínculo de suavidade definiram zonas de intensa silicificação e de QSP. Essas zonas estão diretamente relacionadas a um minério do tipo disseminado, além de terem possibilitado a delimitação da interface saprólito-rocha sã (manto intempérico profundo de até 50 m). Para facilitar a interpretação geológica, foram gerados mapas do campo magnético anômalo reduzido ao equador magnético e da amplitude do sinal analítico. Esse último possibilitou a definição de um stock granítico intrusivo no embasamento heterogêneo. Para eliminar ruídos remanescentes nos mapas de anomalias magnéticas, foram aplicados os filtros cosseno direcional e continuação para cima, com geração de mapa que confirmou o padrão estrutural vigente no Sistema Flor da Serra. Essa estruturação está associada à diferentes níveis crustais, balizam os principais corpos filoneano da região e também estão associadas a alteração QSP. A integração dos principais lineamentos estruturais; bolsões de alta cargabilidade e resistividade; mapeamento detalhado de cavas desativadas e zona de borda da intrusão possibilitou a definição de pontos de interesse prospectivo metalogenético / Abstract: The gold mining area of Flor da Serra is located in the East portion of the Alta Floresta Gold Province (PAAF), North of the state of Mato Grosso, inserted into the geological context of the South-Central portion of the Amazon Craton, which comprises plutono-Paleoproterozoic volcanic suites and associated sedimentary cover. Several gold occurrences are arranged in large zones of crustal discontinuities demarcating land geochronological and geological. The significant densification of filoneano bodies and production history highlights the significant exploration potential of the area. In this context, this study aimed to identify new exploration targets through analysis of geophysical data, description of drill core samples and prospecting pits. The integrated analysis of these data contributed in particular to the development of the geological knowledge of Flor da Serra, and also generally for the eastern sector of the PAAF. The study area covers the Intrusive Suite Flor da Serra which consists essentially of gabbros, diorites to monzogabros, however mapping of prospecting pits and description of borehole samples confirmed the existence of at least four main geological units: (i) granitoids in Basement of tonalitic to granodioritic composition association with magnetite + garnet rocks intruded by (ii) granodioritic to tonalitic of the same composition. This unit is truncated by (iii) the Intermediate Mafic Dykes and locally by (iv) cataclastic to mylonitic rocks. Rocks of the Flor da Serra have been affected by the following hydrothermal alteration types (temporal sequence): (i) intense potassic alteration, (ii) pervasive silicification, (iii) carbonation, (iv) alteration with muscovite, (v) punctual propylitization, (vi) Quartz-Sericite-Pyrite (QSP) alteration with total replacement of the rock and (vii) late calcite veinlets. The geophysical survey consisted of the application of geoelectrical methods (Induced Polarization/Resistivity - IP/RES) and magnetometry at deposit scale. Anomalous values of chargeability and resistivity allowed defining zones of intense silicification and QSP closely related to a disseminated ore type, beyond the boundaries of the saprolite-bedrock interface (deep weathering mantle of up to 50 m). To facilitate geological interpretation, maps of the magnetic anomalous field reduced to the magnetic equador and the analytic signal amplitude were generated. The latter allowed the identification of granitic intrusive stock in heterogeneous basement. To improve the final product and eliminate remaining noise cosine directional filter and upward continuation to 100 m were applied, providing a map which confirmed the structural pattern prevailing in the Flor da Serra system. This structural system is associated with different crustal levels, controls the main filoneano bodies of the region and is attached to QSP alteration. The integration of the main structural lineaments; zones of high chargeability/resistivity; detailed mapping of deactivated pits; and boundary zone of the intrusion led to the definition of prospective metallogenic targets / Mestrado / Geologia e Recursos Naturais / Mestra em Geociências
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Occupation de la plaine de Persépolis au Ier millénaire av. J.-C. (Fars central, Iran) / The Persepolis plain settlement during the first millenium BC (Central Fars, Iran)Gondet, Sébastien 02 April 2011 (has links)
Fondée par Darius Ier (522-486 av. J.-C.), Persépolis constituait une des résidences royales temporaires des souverains de l’Empire achéménide (550-330 av. J.-C.). Elle était également un centre administratif et économique, capitale d’une vaste province, la Perse, située au cœur de l’Empire. L’organisation de Persépolis reste largement méconnue de même que celle du vaste territoire, la plaine environnante, qu’elle contrôlait.Notre étude vise à mieux comprendre d’une part l’occupation du site de Persépolis qui va de la terrasse monumentale à la nécropole royale à 6 km au nord, d’autre part la mise en valeur de la plaine, en replaçant la période achéménide dans le contexte plus large du Ier millénaire av. J.-C. Dans un premier temps, l’étude prend en compte les dynamiques environnementales de la région. Les recherches sont fondées sur les méthodes de prospections archéologiques (reconnaissances à vue et méthodes géophysiques). Elle aboutit à une reconstitution d’une ville répartie en plusieurs blocs de fonctions différentes (habitats ordinaires, zones artisanales, résidences de l’élite et bâtiments de prestige) séparés les uns des autres par de vastes espaces non-bâtis mais probablement aménagés.Pour la plaine (100 km par 30 km), la prospection des sites achéménides a dû prendre en compte les graves destructions liées à la modernisation (agriculture, urbanisation, voies de communication) et s’est concentrée sur quelques sites préservés et des zones de piedmonts sélectionnées. Ces recherches ont montré une occupation très distendue essentiellement localisée dans la partie nord de la plaine et incluant la zone de Persépolis. La partie sud de la plaine était beaucoup moins exploitée. Cependant cette reconstitution doit tenir compte de la réduction sévère du potentiel archéologique, tout particulièrement dans le cadre de l’étude de l’occupation à la période achéménide, lorsque l’exploitation du sol reposait sur des installations rurales de dimensions modestes. / Founded by Darius I (522-486 BC), Persepolis represented one of the seats of the kings of the Achaemenid Empire (550-330 BC). Moreover, the site served as an administrative and economic centre and acted as capital for the vast province, named Persia, situated in the heart of the Empire. The spatial character of both the royal site as well as the wider hinterland it controlled, the vast surrounding plain, are however largely unknown.The study aims at providing better insight in both the occupation of the site of Persepolis, stretching from the monumental terrace to the royal necropolis 6 km farther north, along with that of the supporting plain. It therefore frames and evaluates the Achaemenid period within the context of the first millennium BC. At the outset, the study integrates the environmental dynamics of the region. The research was based on the methods of archaeological survey (field survey and geophysical methods) and allowed to reconstruct a ‘city’ composed of different functional zones (common housing, industrial quarters, elite residences, and royal monuments) separated from one another by large areas, presumably unbuilt though exploited.For the plain (100 by 30 km), the survey of Achaemenid sites was biased by the important destructions by recent development (industrialised agriculture, urbanism, transport and communication). Research has therefore been focussed on a number of preserved sites on the one hand and on selected piedmont areas on the other. These surveys brought to light a scattered occupation, predominantly situated in the northern part of the plain, also encompassing the Persepolis zone, while the southern region of the plain was less occupied. Nonetheless, this reconstruction should take into account the important reduction of archaeological potential, particularly in the case of a study focussing on the Achaemenid occupation since settlement in the wider Persepolis area was first and foremost of rural natural and of rather modest size.
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