698 resultados para Rochas
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Pós-graduação em Engenharia Mecânica - FEG
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Geophysical survey is an important method for investigation of contaminated areas used in the characterization of contrasting physical properties in the presence of pollutants. This work applied the geophysical methods of Electrical Resistivity and Self Potential in waste landfill, located in Caçapava do Sul city, RS. The landfill is located over fractured metamorphic rocks. Eight lines of electrical profiling with 288 measures of self potential were done. In addition, 83 measurements of direction and dip of fractures were taken. The application of spontaneous potential method permitted to detect the direction of groundwater flow. The electrical resistivity measurements allowed the identification of low-intensity anomalies associated with the presence of leachate. There is a relationship between anomalous zones and the directions of fractures.
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The region Indiara (GO) is located in southwestern of São Francisco Craton in the Internal Zone of the Brasília Belt, western part of the Tocantins Province. In this locality outcrop rocks of the Goiás Magmatic Arc. These rocks are muscovite gneiss with biotite, muscovite-biotite gneiss, biotite gneiss with muscovite and garnet, biotite-muscovite gneiss, muscovite porfiroclastic gneiss, biotite porfiroclastic gneiss, muscovite-quartz schists, garnetquartz schists, and metamafic rock (hornblende schists) as metric or kilometric lenses. The gneisses have granodioritic composition, granoblastic texture, with some portions with lepidoblastic texture, constituting a discontinuous centimeter to millimeter banding; the structure is anisotropic, marked by the preferred orientation of all the minerals. These gneisses are leucocratic, generally are inequigranular and fine to medium grained. The hornblende schists have nematoblastic texture, are inequigranular and fine to medium grained and have anisotropic structure that is given by a foliation, marked by a strong preferential orientation of the crystals of amphibole and other minerals present in the rock. The gneisses of the area are composed of plagioclase (oligoclase/andesine), quartz, microcline, muscovite, biotite, epidote, apatite, zircon, garnet, kyanite, oxides and hydroxides of iron and opaque minerals. And the metamafic rocks of Indiara region are composed mainly of amphibole, plagioclase (oligoclase/andesine), quartz, titanite, biotite, allanite, garnet, oxides and hydroxides of iron, apatite, epidote, rutile, muscovite and opaque minerals. At least three phases of deformation were observed in the rocks of area of study (Dn-1, Dn and Dn +1). The Dn phase and represented by a well-marked foliation Sn having low dip angle (average dip of 20 °) and dip direction to SW (210/21) and to NE (18/20); the Dn-1 phase is represented by a compositional banding (Sn- 1), this banding is generally...
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The towns of Castro Alves and Rafael Jambeiro, central-east of Bahia state, are located in the east of São Francisco Craton, in granulite terrains of Salvador-Curaçá Belt, formed in Paleoproterozoic. The region of study contains ortognaisses of Caraíba Complex, metamafic and metaultramafic rocks of São José do Jacuípe Suite, metasedimentary rocks of Tanque Novo-Ipirá Complex, granitoids, pegmatites and alkaline rocks. The study carried out regional and detailed geological mapping in addition to petrographical and geochemical characterization of six areas in the search for targets of feldspar and white diopside, minerals used in ceramic industry. The areas consist of granitic ortognaisses interspersed with lenses of mafic granulite rocks, calc-silicate rock, banded iron formations, paragnaisses, quartzites, and bodies of quartz-feldspar or feldspar pegmatites and alkaline rocks that fill discontinuities. The region of study contains four deformations phases, with a predominance of ductile structures. The foliation Sn has N30E to N70W direction, high angle of dip and is characterized by compositional banding of granoblastic and felsic bands interspersed with nematoblastic or lepidoblastic mafic bands. A mineral or stretching lineation Ln is associated with Sn and has trend of S55E to S72E. The rocks have been suffered a regional metamorphism with granulite facies peak and partial retrogression to greenschist facies. Geochemical studies indicate that the green coloring calc-silicate rocks have lower SiO2, MgO and higher Fe2O3 content compared with white calcssilicate rocks. The alkaline rocks of the studied area have higher Na2O, SiO2 and lower K2O, Fe2O3 content compared with others Paleoproterozoic alkaline rocks of Bahia state. The targets of diopside are associated with white calc-silicate rocks, while the targets of feldspar are associated with paragnaisses, pegmatites and alkaline rocks
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The granitic massif Capão Bonito is located in the southwest of the State of São Paulo and is associated with Neoproterozoic evolution of Central Mantiqueira Province. Its rocks outcrop along the edge of the Paraná Basin in a body with elongated shape whose major axis has a general NE-SW, covering an area of approximately 110km2. Occurs in intrusive epimetamorphic rocks of Votuverava Formation, Acungui Group and granitic rocks of the Três Córregos Complex and their placement is related to a brittle tectonics of NE-SW direction shear zones. In metasediments, when preserved from deformational features imposed by mylonitic deformation, preserve up textures and mineralogy of contact metamorphism with development of mineral in albite-epidote and hornblende hornfels facies. The Massif Capão Bonito consists of red syenogranites, holo-leucocratic with biotite and rare hornblende, medium to coarse inequigranulars and isotropic lightly mylonitic and / or cataclastic in marginal regions. Commercially are called Vermelho Capão Bonito and for export as Ruby Red Granite. Rocks belonging to the calcium-alkaline high potassium to shoshonitic series or the series subalkaline potassic and metaluminous to peraluminous character. The magmatism is compatible with granite type A, tardi-orogenic to anorogenic of intraplate environment, from the crust material with lower melting emplacement associated with correlated transtensive structure to shear zones in an extensional environment at the end of collisional event of Orogênese Ribeira. Metamorphism occurred in the region in the greenschist facies, low to medium, generating quartzites, phyllites, schists, and calcium-silicate metabasics
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Geociências e Meio Ambiente - IGCE
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Pós-graduação em Geologia Regional - IGCE
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Esse trabalho emprega o método para avaliar a abrasividade proposto por Golovanevskiy e Bearman (2008). Esse método, ensaio de abrasão por impacto deslizante (Gouging Abrasion Test), é realizado em condições de alta tensão/alto impacto de desgaste. O método consiste de uma ponteira cilíndrica com uma ponta cônica de 90º, que, em trajetória pendular, atinge uma amostra de rocha com energia de impacto de 300 J e velocidade da ordem de 5,2 m/s. O Gouging Abrasion Index (Gi) é calculado como sendo a média do diâmetro da ponta cônica, após desgaste, em milímetros e o resultado é multiplicado por 10. Esse trabalho verificou a adequabilidade do Gouging Abrasion Test, para um pequeno número de amostras de rocha, que representam, qualitativamente, os principais tipos de rocha encontrados em trabalhos de corte, perfuração e britagem no Brasil, e a sua correlação com outros ensaios consagrados como a resistência à compressão, o desgaste Amsler e a dureza Knoop. Essa análise mostrou alta correlação entre Gi e a dureza Knoop (R² = 0,94), baixa correlação com o desgaste
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Fil: Schinca, Germán. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.
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Fil: Schinca, Germán. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.
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Estudam-se neste trabalho basaltos do local da barragem de Capivara, tanto do ponto de vista de suas características físicas e petrográficas, como de seu comportamento face a solicitações de ensaios que procuram simular condições de intemperismo. Grande parte das rochas apresentou acentuada diminuição da resistência e de desagregação em fragmentos menores. Os estudos experimentais permitiram comparar as rochas entre si do ponto de vista de sua alterabilidade ou alteração potencial, e comparar a velocidade de alteração natural com a experimental. O parâmetro do estado de alteração utilizado foi o da resistência à abrasão Los Angeles, escolhido graças a experiências preliminares e considerações teóricas.
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A análise radiométrica de 36 amostras pelo método K-Ar de rochas localizadas ou próximas do litoral norte do Estado de São Paulo é aqui representada. O trabalho se baseou, principalmente, nasdeterminações em minerais de rochas graníticas, metamórficas e em rocha total de diques básicos, pertencentes à chamada faixa orogênica (cinturão) Paraíba, que se estende ao longo da costa oriental do Brasil. Foram efetuadas determinações em 24 minerais, havendo acentuada preferência nas análises em biotita, por apresentar esse mineral maior retentividade de Ar entre os minerais disponíveis e por ser bastante difundido na litologia da região. Nas rochas intrusivas básicas as análises se concentraram em rocha total, por serem de granulação muito fina e, conseqüentemente, de difícil separação de seus minerais constituintes mais adequados para as determinações radiométricas. Os dados obtidos foram estudados separadamente e o padrão geral das análises apresenta uma boa concordância entre 460 - 470 m.a. para as rochas graníticas e metamórficas e 130 m.a. para os diques, indicando um resfriamento regional após fase de metamorfismo, com posteriores eventos intrusivos no mesozoico.