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La ciudad de Bahía Blanca (Argentina) es un centro regional concentrador de importantes empresas agroindustriales y del sector petroquímico cuyas emisiones son contaminantes de la atmósfera urbana. El objetivo del presente trabajo es analizar la variabilidad temporal de los contaminantes NOX, CO, O3 , SO2 y su relación con los factores naturales y antropogénicos que inciden en su distribución. Los datos fueron obtenidos del sitio web oficial de la Municipalidad de Bahía Blanca, del Servicio Meteorológico Nacional (SMN) y de una estación meteorológica perteneciente a la Universidad Nacional del Sur. El análisis de los mismos se realizó mediante técnicas asociadas a la estadística descriptiva. Se identificó la ocurrencia de contaminación de invierno (winter smog) en distintos episodios producidos por el estancamiento de aire relacionados con las bajas temperaturas, donde los NOx , CO y SO2 fueron preponderantes. La contaminación de verano (summer smog) se asoció a la presencia de O3, vinculada a reacciones fotoquímicas propiciadas por la mayor incidencia de los rayos solares en días calurosos y soleados. Bahía Blanca (Argentina) is a regional center which concentrates many agroindustrial and petrochemical companies whose emissions are polluting from urban atmosphere. The aim of this work is to analyze the temporal variability of NOX, CO, O3, SO2 and its relations with natural and human factors. The analyzed data was taken from the Municipali-ty of Bahía Blanca official website, from the National Meteorological Service (SMN) and from a meteorological station of the Universidad Nacional del Sur. It was performed using descriptive statistics techniques. Winter smog was identified in different episodes caused by the stagnation of air related to low temperatures, where NOx, CO and SO2 were preponderant. Summer smog was associated with the presence of O3, related to photochemical reactions caused by the higher incidence of sunshine on warm and sunny days. Fil: Campo, Alicia Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Geografía y Turismo; Argentina Fil: Fernández, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Geografía y Turismo; Argentina Fil: Gentili, Jorge Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Geografía y Turismo; Argentina

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Umas das técnicas para o processamento das observáveis GNSS, com resultados satisfatórios, é o PPP (Posicionamento por Ponto Preciso). No entanto, a maioria das fontes de erros envolvidas nesta metodologia precisam ser modeladas, ao contrário do que ocorre com o método de posicionamento relativo. Quando são utilizados receptores de duas frequências, uma das fontes de erros mais importantes no PPP se refere à troposfera. O atraso zenital troposférico (ZTD - Zenith Tropospheric Delay), ou refração troposférica, é a principal fonte de erro no posicionamento com GNSS devido à troposfera. Destaca-se que há poucos estudos que comparam os modelos de correção da refração troposférica associados às funções de mapeamento em levantamentos no território brasileiro. Essa pesquisa tem como objetivo principal analisar diversos modelos de refração troposférica e funções de mapeamento no processamento PPP no Brasil, assim como sua influência na acurácia planimétrica e altimétrica das coordenadas finais estimadas. Para tanto, foram investigados os modelos troposféricos de Saastamoinen, Niell, Hopfield, Saastamoinen baseado nos dados de atmosfera do modelo GPT (Global Pressure and Temperature), e o modelo de Previsão Numérica de Tempo do ECMWF (European Centre for Medium-Range Weather Forecasts), aliados as funções de mapeamento de , Niell, Hopfield, GMF (Global Mapping Function), e VMF1 (Vienna Mapping Function 1), disponíveis no software científico BERNESE v. 5.2. Além disso, foi avaliado uma estratégia sem correção a priori do atraso troposférico hidrostático. Os estudos foram realizados nas cinco regiões geográficas do Brasil, e nos períodos de quinze dias para cada estação do ano. Pôde-se constatar que, em relação à acurácia da resultante planimétrica, os modelos de refração troposférica apresentaram resultados similares. Já para a componente altimétrica, o modelo Hopfield não apresentou um desempenho semelhante as outras estratégias de processamento. Além disso, os valores de RMS da acurácia altimétrica apresentaram valores maiores para estações GNSS localizadas na região Norte, principalmente na primavera. Os menores RMS de acurácia altimétrica foram alcançados para estações localizadas na região Sul, na primavera. One of the GNSS observable processing technique, with satisfactory results, is the PPP (Precise Point Positioning). However, the majority of error sources involved in this methodology needs to be modeled, unlike of what happens with the relative positioning method. When double frequency receptors are used, one of the most important source of error in PPP is due to the troposphere. The Zenith Tropospheric Delay (ZTD), or tropospheric refraction, is the main source of error in GNSS positioning due to the troposphere. It stands out that there are few studies that compares tropospheric refraction correction models associated to mapping functions on surveys done on Brazilian territory. This research’s main objective is to analyze various tropospheric refraction in PPP processing in Brazil, as well as its influence on the final planimetric and altimetric coordinates’ accuracy. For this, were investigated the tropospheric models of Saastamoinen, Niell, Hopfield, Saastamoinen based on the GPT (Global Pressure and Temperature) model, and the ECMWF (European Center for Medium-Range Weather Forecasts), allied to the mapping functions of 1 / (cos Z), Niell, Hopfield, GMF (Global Mapping Function), and VMF1 (Vienna Mapping Function 1), available in BERNESE v. 5.2. In addition, a strategy without a priori correction of the hydrostatic tropospheric delay was evaluated. Studies were done for Brazil’s five geographic regions, for 15 days of each season. It was verified that, regarding the planimetric resultant’s accuracy, the tropospheric refraction models showed similar results. For the altimetric component, the Hopfield model did not show similar performance compared to other processing strategies. Moreover, RMS values for the altimetric accuracy were bigger on GNSS station located on the North region, especially during spring. The lower RMS values for altimetric accuracy were achieved on stations located on the south region, on spring.

Orientadora : Prof. Dr. Pedro Luís Faggion Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciências da Terra, Programa de Pós-Graduação em Ciências Geodésicas. Defesa: Curitiba, 16/02/2017 Inclui referências : f. 128-131 Resumo: Um dos problemas encontrados durante levantamentos topográficos é a obstrução de visada dos pontos de interesse, um exemplo disto é verificado em ambientes industriais, onde geralmente existem tubulações e equipamentos que não permitem o estabelecimento de linhas de visada direta. Uma alternativa para aplicação de técnicas topográficas convencionais é o uso de espelhos planos para o desvio de linhas de visada, onde os pontos de interesse são observados indiretamente. Trabalhos anteriores desenvolveram soluções para observações indiretas de pontos baseadas em diversas transformações de sistemas, com uso de espelho, bem como verificaram a influência da configuração do levantamento na qualidade dos resultados. Neste contexto, o presente estudo é uma continuidade destes trabalhos, no qual é apresentada uma nova abordagem para o problema cuja modelagem matemática desenvolvida visa à determinação de coordenadas tridimensionais de pontos ocultos. A solução apresentada fundamenta-se nos princípios da Topografia e da Ótica Geométrica e é realizada em um referencial único, sem a necessidade de transformações recorrentes. Após a proposição inicial, foram realizados aprimoramentos durante o processo de validação, até alcançar sua forma final. Os resultados obtidos indicam a viabilidade do modelo proposto, nos quais a precisão posicional relativa alcançada é de ordem submilimétrica, enquanto no posicionamento absoluto do ponto são da ordem milimétrica. Aliado à isto, testes de consistência foram executados para avaliar o comportamento do modelo em situações heterogêneas da solução, com variação da posição e atitude dos elementos da modelagem matemática proposta. Palavras-chave: Topografia Industrial. Ponto oculto. Espelho plano. Abstract: One of the problems encountered during surveys is obstruction of points to be monitored, an example of this can be found in industrial environments where there are usually pipes and equipment that do not allow the establishment of straight lines. An alternative to the application of topographic survey techniques is the use of plane mirrors to diversion of straight lines where the points of interest are observed indirectly. Previous works have developed solutions for indirect observations of points based on system transformations, using a mirror, as well as verifying of the influence of the configuration of the survey on the quality of the results. In this context, the present study is continuity to these works, in which a new approach is presented to the problem whose mathematical modeling is aimed at the determination of threedimensional coordinates of hidden points. The solution presented is based on the principles of Surveying and Geometric Optics and is performed in a unique frame, without the need for recurring transformations. After the initial proposition, improvements were made to the solution during validation processes until achieving its final form. The results indicate the feasibility of the proposed model, which the relative positional accuracy achieved in the validation tests is submillimetric order, and the absolute positional accuracy is millimetric order. In addition, consistency tests were performed to evaluate the behavior of the model in heterogeneous situations of the solution, with variation of the position and attitude of the elements of the proposed mathematical modeling. Keywords: Industrial surveying. Hidden points. Plane mirror.

O Guaíba ocupa uma depressão topográfica onde desembocam os rios Jacuí, Caí, dos Sinos e Gravataí. Esta extensão de água que se alonga por mais de cinquenta quilômetros e, em sua maior largura, atinge cerca de 18 quilômetros, é chamada popularmente de rio. Também é, algumas vezes designada equivocadamente por estuário. Partindo-se da conceituação sucinta de que estuário, palavra derivada do termo latino “estus” (maré), é “tipo de desembocadura de rio no mar, caracterizada por uma abertura larga e relativamente profunda”, o Guaíba não se inclui nessa designação geográfica. Foi estuário no passado, em época geologicamente recente, anterior à formação da planície costeira e da Laguna dos Patos. Porém, no momento presente, encaixa-se na categoria de lago, desde que consideremos lagos não apenas as porções de água cercadas de terra por todos os lados, sem emissários, mas “depressões continentais ocupadas pelas águas de forma permanente. Muitas vezes são simples episódios no leito de um rio cujas águas ficam retidas por um acidente geológico que forma uma barreira”. Lagos são, em muitos casos, apenas “partes dos sistemas fluviais onde a circulação é menos rápida”. Em consonância com as definições mencionadas no texto, podemos afirmar que as águas lacustres (do Guaíba), não são mais que as mesmas águas fluviais (do Jacuí, do Caí, dos Sinos e do Gravataí) em situação de trânsito e em fim de etapa, pois por especiais circunstâncias morfológicas, aqueles rios não desembocam diretamente no oceano e têm sua foz no lago Guaíba.

Silica permineralized stem fragments from six municipalities of São Paulo, Brazil, belonging to the Passa Dois Group, Corumbataí Formation (Guadalupian, Permian), were analysed. Morpho-anatomic characteristics of the stems and steles, observed on petrographic slides or polished sections, have permitted the classification of many specimens as Tietea cf. Tietea singularis. A stem piece from the region of Casa Branca, determined as Psaronius cf. Psaronius arrojadoi, corresponds to the first true record of this genus in the Paraná Basin. A generic/specific identification was not possible for radicular mantle samples having no preserved steles. Despite the strong influence of taphonomic factors on the record, all known Marattiales fossils from the Paraná Basin in Brazil present relatively small steles and meristeles, and that may be related to hydric stress. Taphonomic, paleoecological and biogeographical aspects of the analysed fossils are discussed as well., Foram analisados fragmentos de caules permineralizados por sílica de filicíneas arborescentes, procedentes de seis municípios do estado de São Paulo, pertencentes ao Grupo Passa Dois, Formação Corumbataí (Guadalupiano, Permiano). Características morfo-anatômicas principalmente dos estelos, observadas em lâminas petrográficas e/ou superfícies polidas dos caules, contribuíram na classificação de diversos exemplares como Tietea cf. Tietea singularis. Um exemplar de Casa Branca, determinado como Psaronius cf. Psaronius arrojadoi, corresponde ao primeiro registro seguro do gênero para a Bacia do Paraná. Não foi possível a identificação genérica/específica das amostras que apresentam apenas os mantos radiculares preservados. Ainda que os fatores tafonômicos tenham influenciado no registro fossilífero, todos os fósseis conhecidos de Marattiales da Bacia do Paraná na porção brasileira exibem estelos e meristelos relativamente pequenos, o que pode sugerir estresse hídrico. São também discutidos aspectos tafonômicos, paleoecológicos e paleobiogeográficos dos fósseis analisados.

The Maraú Peninsula is located on the southern coast of the state of Bahia. Maraú has become a popular tourist destination showing occasional areas of increasing growth and real estate development. The Maraú Peninsula is part of the area of influence for at least two oil and natural gas shallow waters development projects. It is also part of the Northeastern Offshore Exploration Frontier. The aim of this article it to assess the environmental sensitivity of local beaches to erosion and oil spills. The emphasis is given on the two main economic activities with real growth potential for the coming years - tourism and oil production. Beach sensitivity to erosion was established from the current shoreline behavior trend. The following beaches were classified according to their sensitivity to erosion: i) Very High Sensitivity: beaches of Barra Grande, Taipus de Fora, Cassange, Saquaíra, Arandi, Algodões, Aibim; ii) High Sensitivity: portions of Piracanga beach, near the mouth of Contas River and Boca da Barra beach; and iii) Average Sensitivity: the beaches of Três Coqueiros, Ponta do Mutá, Bombaça and Humberto. These beaches were also classified according to their sensitivity to oil spills according to the U.S. National Oceanic and Atmospheric Administration - NOAA methodology: Average Sensitivity: Bombaça, Cassange, Humberto, Arandi; Very High Sensitivity: all remaining beaches 147 148 1.Introdução petroleiros, entre os quais alguns com capacidade de transportar mais de 500 mil toneladas (ITOPF, A erosão costeira representa um problema 2009). ambiental e social em áreas urbanas quando ameaça Tanto o número quanto o volume total de derrames as construçõesqueimpedemolivrerecuodalinhade acidentais vêm sendo reduzido desde 1980, mas costa, passando a representar assim um risco à apesar disso, em razão do grande tráfego de infraestrutura costeira e reduzindo a capacidade petroleiros, o risco de derrames sempre está recreacional da praia (Bird, 1985; Pilkey, 1991; presente, seja por acidentes, negligência, guerras, Lizárraga-Arcineiga et al., 2001). Com o aumento da terrorismo,etc. demandapor estas regiões. aumenta tambémovalor O petróleo e seus derivados são introdas propriedades costeiras e as modificações na duzidos em ambientes marinhos de várias maneiras posição da linha de costa geram um alto risco para diferentes. Os acidentes que resultam em derrames estas construções (White, 1978; Komar et al. 1991; inevitavelmente se tornam manchetes nos jornais, Gares et al., 1994; Camfield & Morang, 1996; mas, na realidade, estes representam apenas Appendini & Fisher, 1998). Além de constituir uma aproximadamente 5% de todo o óleo que chega aos ameaça ambiental, a perda da praia recreativa por oceanos. O grande volume de óleo chega mesmo aos erosãorepresentatambémumarestriçãoàatividade oceanos através de fontes terrestres, como esgotos, turísticaonde apraia configura impor-tante atrativo. vazamentos, emissões industriais, etc. (ITOPF, Desta forma, o conhecimento dos locais mais 2009). Outros impactos de derrames marinhos propensos ou vulneráveis à erosão costeira re- incluem: presenta uma importante ferramenta de plane- Ÿ a presença de óleo causa um significativo jamento e gestão, podendo balizar decisões impacto no apelo turístico de áreas costeiras. O preventivas, evitando a ocupação dessas áreas ou a petróleo bruto e seus refinados podem causar construção de estruturas que alterem o delicado explosõeseincêndio. equilíbrio no balanço sedimentar da praia e das Ÿ derrames interferem no funcionamento de regiõescosteirasadjacentes. plantas hidroelétricas e na rotina operacional de Outra ameaça à qualidade ambiental e indústriascosteiraseportos. recreativa das praias é a produção e transporte de Ÿ efeitos no ecossistema marinho são caupetróleo e seus derivados. Ainda que relacionada a sados pela natureza física do óleo e por sua incidentes episódicos, a poluição associada à composição química. Danos em populações de indústria petrolífera pode provocar impactos plantas e animais podem ser catastróficos e irrecatastróficos e irreversíveis sobre determinados versíveis. No mínimo, a recuperação biológica ecossistemas, principalmente naqueles onde os podelevarmuitosanos. métodos de limpeza existentes são na sua maioria Ÿ derrames podem causar danos em equiineficientesouinadequados, comonosmanguezais e pamentos de pesca e em instalações de recifes de corais. A intensificação da atividade maricultura, comprometendo a confiabilidade exploratóriadepetróleoegásnaturalemáguas rasas dosprodutosdosetor. dolitoraldoBrasileaperspectivadesucessoseguido Ÿ a vida marinha, estruturas naturais e do desenvolvimento e estabelecimento de unidades construções podem ser danificadas ou desprodutoras têm gerado incertezas e conflitos, truídas durante operações de mitigação e especialmente em pequenas localidades e vilas que reabilitação. dependemeconomicamentedapescaedoturismo. OBaixo Sul está sujeito a dois tiposde riscos: Quanto a derrames, em média, men- pequenos vazamentos crônicos resultantes das salmente, mais de 100 milhões de toneladas de óleo atividades de extração; e grandes e catastróficos bruto são embarcadas ao redor do mundo. vazamentos oriundos de petroleiros em passagem Geralmente, o transporte é feito em grandes pelaregião. with very high sensitivity to oil spills, especially due to the presence of fragile ecosystems such as coral reefs and mangroves forests. Most beaches on the peninsula are undeveloped, maintaining their natural characteristics. However, these same beaches are classified as having High to Very High Sensitivity to erosion and Very High Sensitivity to oil spills. The beaches in the villages of Saquaíra and Algodões are emerging real estate development vectors in the region. These beaches currently present average levels of urbanization and are classified as having Very High Sensitivity to erosion and oil spills. The implementation of precautionary policies associated with management of the coastline is critical to minimize social and environmental conflicts that, in general, result in pollution, acceleration of erosion and frustration of local communities., A Península de Maraú, localizada no litoral sul do estado da Bahia, apresenta reconhecida vocação turística e vem apresentando, pontualmente, índices elevados de crescimento e ocupação. Adicionalmente, a Península de Maraú é parte da Área de Influência do Segmento Offshore de Petróleo, envolvendo a exploração e produção de hidrocarbonetos em águas rasas. Este artigo pretende avaliar a sensibilidade ambiental aos derrames de óleo e à erosão das suas praias, com foco nas duas principais atividades econômicas (Turismo e Produção de Petróleo) que vislumbram crescimento elevado para os próximos anos. A sensibilidade das praias à erosão foi estabelecida a partir da tendência atual de comportamento da linha de costa, sendo consideradas com sensibilidade à erosão i) muito alta, nas praias de Barra Grande, Taipus de Fora, Cassange, Saquaíra, Arandi, Algodões, Aibim; ii) alta, na porção praia de Piracanga, próximo à desembocadura do Rio de Contas; e iii) média, nas praias de Três Coqueiros, Ponta do Mutá, Bombaça e Humberto. As praias da Península de Maraú foram classificadas em relação à sua sensibilidade para derrames de óleo de acordo com a metodologia desenvolvida pelo U. S. National Oceanic and Atmospheric Administration-NOAA. Utilizando esta classificação, de acordo com as principais características observadas nas praias, as praias de Bombaça, Cassange, Arandi e Humberto foram consideradas com sensibilidade média e as demais com sensibilidade muito alta a derrames de óleo, especialmente devido à presença de ecossistemas sensíveis, como os recifes de corais e manguezais adjacentes à costa. A maior parte das praias da Península são pouco urbanizadas e apresentam uma sensibilidade alta a muito alta à erosão e muito alta a derrames de óleo. As praias das vilas de Saquaíra e Algodões, potenciais vetores de crescimento na região, apresentam nível de urbanização médio, sensibilidade muito alta à erosão e derrames de óleo. É essencial a implementação de políticas preventivas associadas à gestão deste litoral, a fim de minimizar conflitos sociais e ambientais que, em geral, resultam em poluição, aceleração do processo erosivo e insatisfação das comunidades locais.

The Várzea do Capivarita Metamorphic Complex, situated in the region of Encruzilhada do Sul, RS, is part of the Sul-rio-grandense Shield. It encompasses an orthometamorphic sequence of tonalitic composition, as well as pelitic and calc-silicate paragneisses. Ortho and paragneisses are interleaved as 3- to 4 meter thick slabs, in average, where parageneses and microstructures are compatible with granulite-facies metamorphism. An integrated approach consisting of field observations, structural geology and petrography permits to discuss the geological evolution of this complex. Additionally, major and traceelement data were obtained from the tonalitic gneisses in order to investigate the nature of the magmatism which has generated their protoliths. The gneisses exhibit a NNW-striking metamorphic banding , dipping variably toward ENE or WSW, which bears a stretching lineation of generally high rake angle. The original orientation of the banding, later fold effects being suppressed, is interpreted to have been sub-horizontal. The piling of different lithological units, regarding composition and geological environment, along originally sub-horizontal planes leads to their interpretation as a thrust pile. The orientation of high-grade mineral assemblies along the banding of all lithological types indicates that this thrust tectonics has taken place under granulite-facies metamorphic conditions. The tonalitic gneisses are metaluminous to peraluminous and belong to the calcalkaline series. Their composition and trace- element patterns suggest that they are representative of a continental arc magmatism comparable to the one described in the Encantadas Complex, a Paleoproterozoic magmatic arc assembly from the Sul-rio-grandense Shield. Based on their compositional and stratigraphic similarities with the Encantadas Complex, the studied tonalitic orthogneisses are interpreted to be part of the same Paleoproterozoic continental margin magmatism. It is assumed that the granulite-facies metamorphic event is of Neoproterozoic age. Additionally, it would have been synchronous with the thrust event that lead to the tectonic interleaving of rock sequences of different provenance and age that has generated the Complex., O Complexo Metamórfico Várzea do Capivarita situa-se na região de Encruzilhada do Sul, RS, e faz parte do Escudo Sul-rio-grandense (ESRG). Congrega rochas ortometamórficas de composição tonalítica, além de paragnaisses pelíticos e calciossilicáticos. Orto e paragnaisses são intercalados em fatias de 3 a 4m de espessura média e apresentam paragêneses e microestruturas compatíveis com metamorfismo de fácies granulito. A abordagem integrada de geologia de campo, geologia estrutural e petrografia permitiu discutir a história evolutiva do Complexo. Para a investigação dos ortognaisses foram obtidos também dados geoquímicos de elementos maiores e traços, o que tornou possível estabelecer as características do magmatismo gerador de seu protólito. As rochas do Complexo possuem bandamento de direção preferencial NNW e mergulho variável, para ENE e WSW, contendo lineação de estiramento geralmente de alta obliquidade. A atitude original do bandamento, retirados os efeitos de dobras, é interpretada como suborizontal. O empilhamento de sequências de composição e ambientes de formação distintos ao longo de estruturas originalmente suborizontais indica um regime tectônico do tipo cavalgamento, e o registro de paragêneses de alto grau orientadas segundo o bandamento em todos os tipos litológicos sugere que esta tectônica ocorreu em condições de fácies granulito. Os gnaisses tonalíticos são meta a peraluminosos e pertencem à série cálcio-alcalina. Sua composição e padrões de elementos traços sugerem que representam um magmatismo de arco continental, correlacionável ao Complexo Encantadas, uma associação de arco magmático paleoproterozóica do ESRG. Deste modo, os ortognaisses estudados, por sua similaridade composicional e estratigráfica com o Complexo Encantadas, são interpretados como parte do mesmo magmatismo de margem continental ativa. Presume-se que o metamorfismo de fácies granulito tem idade neoproterozóica e teria sido contemporâneo à tectônica de empurrão responsável por justapor litologias de idade e origem diversa, gerando o Complexo.

This study aims at characterizing the distribution of bottom surface sediments in the lower course of Pará river, more precisely in the area of influence of the Vila do Conde Port, Barcarena region, state of Pará. Based on the available bathymetric map, a grid of 254 points was established for collecting bottom surface sediments. The samples were then submitted to classical particle size analysis (sieving and centrifugation) to enable textural characterization, and were analyzed for grain size distribution and organic matter. The chart of bottom sediment distribution shows a dominance of litoclastic medium sand, and litoclastic sand with gravel. The distribution of bottom sediments is closely related to the bottom morphology and indicates high to very high hydrodynamic conditions for this area. The poorlyselected, medium, coarse and very coarse sands with gravel occur in the channel to the Port of Vila do Conde, characterizing it as the sector of highest hydrodynamic energy. Other areas of deposition of coarse sediments correspond to the river banks associated with sediment input due to erosive action. The northern portion of the study area features the highest percentages of organic matter, which would be closely related to the higher adsorption capacity of its muddy sediments. The contribution of organic matter is mainly due to the local input of vegetation from floodplain areas, and secondarily to organic debris from the urban area of Vila dos Cabanos. The relevance of this study is to portrait the current sedimentological features of Vila do Conde Port area for future comparison with eventual changes related to natural and/or anthropogenic variants, due to recurrent industrial and port activities in the area., Este trabalho objetiva caracterizar a distribuição superficial de sedimentos de fundo do baixo curso do rio Pará, mais precisamente na área de influência do Porto de Vila do Conde, município de Barcarena, estado do Pará. A partir da carta batimétrica disponível para a área foi elaborada uma malha de amostragem composta por 254 pontos de coleta de sedimentos de fundo, cujas amostras foram submetidas às análises granulométricas clássicas (peneiramento e centrifugação) para a devida caracterização textural. Através da carta de distribuição de sedimentos de fundo gerada observa-se o predomínio de areia litoclástica média e areia litoclástica com cascalho. A distribuição sedimentológica de fundo apresenta estreita relação com a morfologia e, sobretudo, evidencia características de hidrodinâmicas altas a muito alta para esta área. As areias médias, grossas e muito grossas com cascalho, mal selecionadas, ocorrem no leito do canal de acesso ao Porto de Vila do Conde, caracterizando-o como o setor de mais alta energia hidrodinâmica. Outros setores de deposição de sedimentos grossos correspondem às margens do rio, onde os depósitos estão associados ao input sedimentar decorrente da ação erosiva. A porção mais ao norte da área estudada concentra as maiores percentagens de matéria orgânica, que estaria intimamente relacionada aos sedimentos lamosos que apresentam maior capacidade de adsorção deste material. Esta contribuição de matéria orgânica está relacionada, principalmente, ao aporte local de material de origem vegetal das áreas de várzea e, secundariamente, ao aporte de detritos orgânicos provenientes da área urbana da Vila dos Cabanos. A relevância da análise está na apresentação das atuais características sedimentológicas da área submersa do Porto de Vila do Conde para futuras comparações com eventuais modificações relacionadas com variantes naturais e/ou de cunho antropogênico, visto as recorrentes atividades industriais e portuárias na área.

The use of an electron microprobe (EPMA) integrated with inductively coupled plasma mass spectrometer laser ablation (LA-ICP-MS) for the determination of major and trace elements in igneous minerals advances the knowledge of the distribution coefficients “D”in cores, intermediate portions and rims of crystals. Crystals of clinopyroxene and plagioclase of tholeiitic sills from the Serra Geral Formation, Paraná Basin, Brazil, display positive correlations between many major and trace elements. Plagioclase has core concentrations of SiO2 and Na2O wt.% which increase to the rim and Al2O3 and CaO wt.% decreasing from the core to the rim, corroborated by similar variations of distribution coefficients of Sr and Eu as a result of substitution of these compatible elements for Na in the structure of plagioclase. Clinopyroxene has the decreases in MgO, Al2O3 and CaO wt.% core to the rim and decreased D of Ni, Zn and V, and to increased concentration of FeOtotal wt.% core to the rim related increase in D of Sc, Y andHREE. This investigation is innovative because it presents the study of distribution coefficients oftrace elements with spatial control of the analyses, taking into account the effect of inclusions, fractures and compositional zoning., A utilização de técnicas de microanálise (microssonda eletrônica - EPMA e ablação a LASER em espectrômetro de massa com plasma indutivamente acoplado - LA-ICP-MS) de elementos maiores, traços e terras raras em minerais ígneos amplia o conhecimento do coeficiente de distribuição “D” em porções de núcleo, intermédio e borda do cristal. Cristais de clinopiroxênio e plagioclásio de sills toleíticos da Formação Serra Geral, Bacia do Paraná, Brasil, possuem correlações positivas entre muitos elementos maiores e traços. O plagioclásio possui em seu núcleo concentrações de SiO e Na O (peso %) 2 2 que aumentam para a borda e concentrações de Al O e CaO (peso %) que diminuem do núcleo para a 2 3 borda do cristal. Isto é corroborado pelas mesmas variações dos coeficientes de distribuição de Sr e Eu em decorrência de substituições destes elementos, nas posições estruturais do Na no plagioclásio. O clinopiroxênio mostra decréscimo nos conteúdos de MgO, Al O e CaO (peso %) do núcleo para a borda, 2 3 diminuição dos D de Ni, Zn e V e aumento das concentrações de FeO (peso %) do núcleo para a borda total relacionados com o aumento do D de Sc, Y e ETR pesados. Este trabalho é inovador, pois apresenta o estudo de coeficientes de distribuição de elementos traços com controle espacial das análises, controlando- se desta forma, a influência de inclusões, fraturas e zoneamentos composicionais.

The Arroio dos Ratos Complex is part of the Pelotas Batholith basement in the Sul-rio-grandense Shield. Geological and structural mapping of its type-section, in the region of Quitéria, RS, has led to the discrimination of the so-called Association 1 (A1), consisting of foliated tonalitic to dioritic rocks discordantly intruded by compositionally similar ones. Their basement comprises calc-silicate and tonalitic gneisses, as well as metavolcano-sedimentary rocks. The A1 rocks are medium- to coarse-grained, garnet-bearing biotite metatonalites, and mafic-rich, fine-grained metadiorites to metatonalites, where garnet is restricted to the most differentiated varieties. Field relations indicate that these fine-grained varieties have intruded the coarser ones as synplutonic dykes. The granoblastic texture found in both rock groups is attributed to their recrystallization under temperatures compatible with upper amphibolite to granulite facies conditions. The main foliation, S1 , is NW- to EW-striking, and its variation is attributed mainly to the 1 effect of F2 folding, whose axes plunge with low to moderate angles towards WSW, and coincides with the stretching lineation position. The original orientation of S1 , later fold effects being suppressed, is interpreted to have been sub-horizontal, with shallow dip angles towards WSW. Sense of movement determined from macro- and micro-scale structures indicates top-to-E. The A1 metatonalites and metadiorites are meta- to peraluminous rocks and belong to the medium to high-K calc-alkaline series. The behavior of major and trace elements, together with moderately fractionated REE-patterns, with enrichment of LREE in relation to HREE, indicate that this magmatism took place in a mature continental arc environment, and that the A1 is comparable to other TTG associations. Preliminary data indicate a Paleoproterozoic age for the A1 rocks. The information gathered in this paper enables the comparison of this association with the Encantadas Complex orthogneisses, although the latter show stronger effects of regional, orogenic metamorphism. Thus, the A1 rocks are interpreted to represent the more mature phase of the same magmatic arc where the Encantadas Complex protoliths were formed., O Complexo Arroio dos Ratos faz parte do embasamento do Batólito Pelotas, no Escudo Sulrio-grandense. O mapeamento geológico-estrutural de sua seção-tipo, na região de Quitéria, RS, levou à identificação de um conjunto de rochas tonalíticas a dioríticas foliadas, denominado Associação 1 (A1), intrudido discordantemente por rochas de composição similar. O embasamento destes tipos litológicos compreende gnaisses calcissilicáticos, gnaisses tonalíticos e rochas metavulcano-sedimentares. A A1 é composta por granada-biotita metatonalitos de granulação média a grossa e por metadioritos a metatonalitos de granulação fina, com granada restrita aos termos mais diferenciados. As relações de campo indicam que os termos finos constituem diques sinplutônicos intrudidos nos demais. Em ambos os grupos, a textura granoblástica é atribuída à recristalização sob temperaturas compatíveis com as da fácies anfibolito superior a granulito. A foliação S tem direção NW-SE a EW e a sua dispersão é atribuída 1 principalmente aos efeitos das dobras F2 , cujo eixo tem caimento baixo a médio para WSW, coincidente com a posição da lineação de estiramento, LX . Retirando-se os efeitos das dobras F2 , a geometria original da foliação na A1 teria sido sub-horizontal, com mergulho suave para WSW. O sentido de movimento dado por estruturas de macro e microescala indica topo para E. Os metatonalitos e metadioritos da A1 são meta a peraluminosos e pertencem à série cálcio-alcalina de médio a alto-K. O comportamento dos elementos maiores e traços e o padrão de fracionamento moderado dos ETR, com enriquecimento dos leves em relação aos pesados, indicam ambiente de arco continental maduro para o magmatismo desta associação e a mesma é comparável a associações TTG. Dados preliminares situam a A1 no Paleoproterozóico e o conjunto das informações permite compará-las aos ortognaisses do Complexo Encantadas, embora estes registrem com mais intensidade o metamorfismo regional orogênico. Assim, presume-se que as rochas da A1 representem o registro da fase mais madura do mesmo arco continental onde teria se gerado o Complexo Encantadas.

The Serra Geral Formation has a wide distribution in the western region of Rio Grande do Sul (200 x 200 km) and consists of six tholeiitic lava flows which constitute the Alegrete facies. This number of lava flows was evidenced through geological mapping integrated with lithological and scintillometric description of 19 boreholes drilled for groundwater by the Geological Survey of Brazil (CPRM) in the years 1983-1986. The general thickness of the Alegrete facies is, A Formação Serra Geral ocupa uma área de cerca de 200 x 200 km na região oeste do Rio Grande do Sul e consiste de seis derrames de lavas toleíticas, que constituem a fácies Alegrete. Esse número de derrames foi constatado em mapeamento geológico, integrado com a descrição geológica e com a perfilagem cintilométrica de 19 furos de sonda efetuados para água subterrânea pelo Serviço Geológico do Brasil (CPRM) nos anos 1983-1986. A espessura média da fácies Alegrete é inferior a 100 m, atingindo até 300 m no furo UR-13. As dunas da Formação Botucatu foram parcialmente soterradas pelo derrame Mata Olho (basalto), seguido pelos derrames Catalán (andesito), Cordillera, Muralha, UR- 13 e Coxilha (andesitos basálticos). As medidas cintilométricas são típicas de cada derrame,variando entre 45-120 cps, e servem como guia estratigráfico, especialmente com o uso integrado com as observações de campo e litoquímica. Este estudo apresenta uma forma de abordagem integrada entre diferentes ferramentas geológicas aplicadas à estratigrafia de basaltos, possibilitando o mapeamento geológico sistemático de cada derrame em escala regional, com grande significado para o entendimento da geologia da Formação Serra Geral.

The area of Camaquã Mines is part of the camaquã basin, which has NE-NW directions and is filled out by silliciclastics sediments interbedded with volcanic rocks. Chlorite is the most abundant clay mineral in the area and appears in high amount in the halos of hydrothermal alteration present in the host's mineralization rocks. This work consists on the chlorite's petrologic, chemical and structural characterization, supplying important information on different processes and formation conditions of the hydrothermal environment. The following procedures were made: optical petrography, X-ray diffraction, difractograms modeling through the Reynolds Newmod© program, and scanning electron microscopy ( secondary electrons and microanalysis - EDS) in representative samples of the different identified hydrothermal alteration zones. Chlorites are present under three different tendencies: Chlorite I takes place with a pervasive aspect over the matrix rocks located near the mineralized veins; it is classified as Fe-chlinoclore, presents fraction ˂1 µm predominance of plytype IIb and a Mg2+ enrichment in the fraction of ˂10 µm predominance of polytype Ib (90°) and Fetotal enrichment. Chlorite II occurs as veins filling out small fractures; it is classified as Chamosite and presents structural polytype IIb. Chlorite III occurs altering detrital minerals; it is classified as Mg-chamosite. The variation on the amount of Fe of the chlorites generated over the hydrothermal processes ( Chlorite I ˂10 µm and Chlorite II) indicates the occurrence of at least two pulses in the process of the hydrothermal alteration: one is responsible for the great matrix and clasts alternation and the other one for the generation of the late veins. The variation in the amount of Fetotal of the two different responsible fluids for the crystallization of the chlorites is was quite more enriched in iron than the early fluid that crystallized Chlorite I ˂10 µm., A região das Minas do Camaquã é a parte constituinte da Bacia do Camaquã, a qual possui direção NE-NW e é preenchida por sedimentos siliciclásticos intercalados com rochas vulcânicas. A clorita é o argilomineral mais abundante da área, ocorrendo em grande quantidade nos halos de alteração hidrotermal presentes nas rochas encaixantes nas mineralizações na Mina Uruguai. Este trabalho consiste na caracterização petrológica, química e estrutural das cloritas, que fornece importante informações sobre diferentes processos e condições de formação do ambiente hidrotermal. Para isso se realizou petrografia óptica, difratometria de raios X, modelamento dos difratogramas através do programa Reynolds Newmod © e microscopia eletrônica de varredura (elétrons secundários e micro-análises por EDS) em amostras representativas de diferentes zonas de alteração hidrotermal identificadas. As cloritas se apresentam com três diferentes tendências: a Clorita I ocorre com aspecto pervasivo sobre matriz das rochas localizadas próximos aos filões mineralizados; é classificada como Fe-clinocloro, apresenta na fração ˂1 µm predominância do politipo IIb e um enriquecimento em Mg2+ e na fração ˂10 µm predominância do politipo Ib (90°) e enriquecimento em Fetotal . A Clorita II ocorre com veios preenchendo pequenas fraturas; é classificada como Chamosita e apresenta politipo estrutural IIb. A Clorita III ocorre alterando minerais detríticos sendo classificada como Mg-Chamosita. A variação na quantidade de ferro das cloritas geradas por processos hidrotermais ( Clorita I ˂10 µm e Clorita II) fornece indícios da ocorrência de pelo menos dois pulsos no processo de alteração hidrotermal: um responsável pela intensa alteração da matriz e dos clastos das rochas e outro responsável pela geração de veios tardios. A variação na quantidade Fetotal dos dois diferentes fluidos responsáveis pela cristalização das cloritas fica evidenciada pela associação de co-genecidade da Clorita II com a hematita, mostrando que o fluido final foi muito mais enriquecido em ferro que o fluido precoce cristalizou a Clorita I ˂10 µm.

Esse trabalho apresenta os conodontes encontrados em cinco afloramentos da porção inferior da Formação Itaituba, no Sul da Bacia do Amazonas, região Norte do Brasil, unidade pensilvaniana que compreende o intervalo mais rico e diversificado em organismos de ambiente marinho raso da bacia. A seção estudada consiste, estratigraficamente da base para o topo, em dois afloramentos junto ao Rio Tapajós e três pedreiras de calcário, situadas próximo à cidade de Itaituba, Estado do Pará. A associação de conodontes inclui Idiognathodus incurvus, Idiognathoides sinuatus, Neognathodus bothrops, N. bassleri, N. medadultimus, N. atokaensis, N. roundyi, Adetognathus lautus, Hindeodus minutus, Diplognathodus coloradoensis, D. orphanus, D. ellesmerensis, Rhachistognathus muricatus, Idioprioniodus sp., Ellisonia latilaminata, E. conflexa, Ubinates advena e Gondolella sp. São propostas duas zonas de amplitude de táxon: Rhachistognathus muricatus e Diplognathodus orphanus, e uma zona de associação: Idiognathodus incurvus / Neognathodus atokaensis / Neognathodus medadultimus. Neognathodus atokaensis, Diplognathodus orphanus e Idiognathodus incurvus caracterizam uma idade atokana. A ocorrência de Rhachistognathus muricatus, de idade morrowana, na porção inferior do perfil e a presença de espécies atokanas acima, permitem determinar cronoestratigraficamente o limite Morrowano / Atokano. As associações de conodontes observadas são representadas principalmente por espécimes típicos de contextos ambientais de intermaré/inframaré e menos comuns representantes da intermaré/barra bioclástica/supramaré.

In this work, the use of genetic algorithms is proposed as detectors of straight line segments that characterize a rural road. The segment detection process consists of iterative procedures on digital images, where each step results in two possible segments for the centerlines. The validation of the results produced by the proposed algorithms was based on a manually vectorized reference image. The accuracy index was computed as the percentage of wrongly detected pixels. Despite the modest number of experiments, the results have shown the proposed method to be promising., Nesse trabalho, é proposto o uso dos algoritmos genéticos no processo de detecção de linhas retas, ou segmentos, que caracterizam o eixo de estradas vicinais. O processo de detecção de segmentos é realizado de forma iterativa, em imagens digitais, onde dois segmentos candidatos ao eixo de estradas são detectados em cada passo (iteração). A validação dos resultados, obtidos pelo método proposto, foi realizada com base em uma imagem de referência, vetorizada manualmente. O índice de acurácia foi computado como a porcentagem de pixels detectados erroneamente. Embora o número de experimentos seja modesto, os resultados mostram que o método proposto é promissor.

The growth of large cities is usually accelerated and disorganized, which causes social, economical and infrastructural conflicts and frequently, occupation in illegal areas. For a better administration of these areas, the public manager needs information about their location. This information can be obtained through land utilization and land cover maps, where orbital images of remote sensing are used as one of the most traditional sources of data. In this context, the present work tested the applicability of the object-based classification to categorize two slum areas, taking into account the structure of the streets, size of the huts, distance between the houses, among other parameters. These area combinations of physical aspects were analyzed using the image IKONOS II and the software eCognition. Slum areas tend to be, to the contrary of the planned areas, disarranged, with narrow streets, small houses built with a variety of materials and without definition of blocks. The results of land cover classification for slum areas are encouraging because they are accurate and little ambiguous in the classification process. Thus, it would allow its utilization by urban managers., O crescimento das grandes cidades geralmente ocorre de forma acelerada e desorganizada, ocasionando conflitos de ordem social, econômica e de infra-estrutura, gerando, frequentemente, áreas de ocupação ilegal. Para um melhor gerenciamento dessas áreas, o gestor público necessita de informações sobre a localização delas. Estas informações podem ser obtidas por meio de mapas de uso e cobertura da terra, sendo as imagens orbitais de sensoriamento remoto uma das fontes mais tradicionais de dados para confecção destes mapas. Neste contexto, o presente trabalho testou a aplicabilidade da classificação orientada a objetos para categorizar duas áreas faveladas, levando em consideração a estrutura dos arruamentos, tamanho dos barracos, distância entre as casas, entre outros parâmetros. Essas combinações de aspectos físicos da área foram analisadas com a ajuda da imagem IKONOS II e do software eCognition. Áreas faveladas, contrariamente às áreas planejadas, tendem a ser desarranjadas, com ruas estreitas, casas pequenas e construídas com os mais variados materiais e sem definição de quadras. Os resultados das classificações de cobertura para áreas de favelas são encorajadores, já que se mostraram precisos e pouco ambíguos no processo de classificação, o que permitiria a sua utilização por gestores urbanos.

Anhydrous spinel-bearing peridotite and pyroxenite xenoliths in Pleistocene alkali basalts from the Agua Poca volcano, Argentina, were sampled for this study and represent the Cuyania Subcontinental Lithospheric Mantle (Cuyania SCLM). Agua Poca mantle xenoliths are depleted, but is possible to identify metasomatic event through the incompatible elements enrichment, due the interaction of the mantle lithosphere with aqueous fluid derived from slab subduction in a continental extra back-arc tectonic setting. Geochemical signatures of the studied samples show negative correlation for main oxides against Mg#, and depletion of incompatible elements compared to the Primitive Mantle (PM). Considering non-modal batch melting model, it is possible to attribute to SCLM below Cuyania Terrane 1 to 10% of partial melting DMM or 8 to 17% of partial melting Primitive Mantle. According to geochemical models considering mixing between end members (melting residue from PM/DMM and fluid or sediment compositions related to subduction tectonic setting) it is possible to suggest up to 3% of metasomatic enrichment in the Agua Poca SCLM. 87Sr/ 86Sr ratios (0.702874 - 0.704999, with average of 0.704035) are similar to those 87 86 defined to OIB sources peridotites ( Sr/ Sr = 0.70244 to 0.70502) and are close to Depleted Mantle ratios (DM; 87Sr/ 86Sr = 0.7023 to 0.7032). Agua Poca mantle xenoliths show 87Sr/ 86Sr lower than those defined to metasomatized peridotites (usually > 0.705). Nb/Ta ratios suggest a refractory eclogitic reservoir, which by partial melting generated alkaline/carbonatitic magmas with superchondritic Nb/Ta ratios., O manto litosférico subcontinental (MLSC) do terreno Cuyania está representado em xenólitos peridotíticos e piroxeníticos anidros da fácies espinélio hospedados em basaltos alcalinos pleistocênicos do vulcão Agua Poca, Província Basáltica Andino-Cuyana, Argentina. Os xenólitos manté- licos do vulcão Agua Poca são depletados, mas é possível identificar a influência de processos metassomáticos através do enriquecimento em elementos incompatíveis devido à interação com fluidos aquosos em um ambiente de extra back-arc continental. A composição geoquímica das amostras estudadas mostra correlação negativa entre os principais óxidos vs. #Mg, e padrão empobrecido em elementos incompatíveis em relação ao Manto Primitivo (MP). Com base em cálculos de fusão parcial em equilíbrio não modal é possível atribuir ao MLSC abaixo do terreno Cuyania taxas de fusão de 1 a 10% a partir do Manto do tipo MORB Depletado e de 8 a 17% a partir do Manto Primitivo. Curvas de mistura calculadas para o resíduo de fusão do MP/MMD com a composição de fluidos/sedimentos derivados de ambientes de subducção indicam interação do manto com até 3% de fluidos/sedimentos. As razões 87 Sr/ 86Sr (0,702874 - 0,704999, com média de 0,704035) são muito similares àquelas definidas para peridotitos com fonte tipo OIB e estão próximas às definidas para o Manto Depletado (DM; 87Sr/ 86Sr = 0.7023 to 0.7032). Os xenólitos mantélicos do vulcão Agua Poca têm razões 87Sr/ 86Sr inferiores àquelas definidas para peridotitos metassomatizados (usualmente >0,705). As razões de Nb/Ta sugerem a presença de um reservatório eclogítico refratário subductado, que por fusão parcial gerou líquidos alcalinos/carbonatíticos com razões Nb/Ta supercondríticas.

Early-authigenic K-feldspar overgrowths are widespread in the Cretaceous fluvial Açu Formation sandstones from the Potiguar Basin, one of the most important onshore oil reservoirs of Brazil. These overgrowths were formed at near-surface conditions (early eodiagenesis), directly on detrital Kfeldspar grains. The physical continuity between overgrowths and K-feldspar grains rendered impossi ble their separation by conventional means for 40K- 40Ar isotope analysis. An in situ 40Ar- 39Ar step-heating method was, therefore, applied and the minimum age of 120 Ma obtained for the authigenic overgrowths agrees with the depositional biostratigraphic age previously estimated for the Açu Formation. The method applied to the Açu Formation sandstones shows excellent potential for depositional age determination of other reservoir-sandstones. We suggest that future developments of the method will, however, greatly benefit from the use of ultra-violet (UV) laser for reducing chances of contamination of authigenic K-feldspar overgrowths analyses by detrital grains., Crescimentos autigênicos precoces de K-feldspato são abundantes nos arenitos fluviais cretácicos da Formação Açu (Bacia Potiguar), um dos mais importantes reservatórios onshore de hidrocarbonetos do Brasil. Estes crescimentos foram formados diretamente ao redor de K-feldspatos detríticos, em condições superficiais (eodiagênese inicial). A continuidade física entre crescimentos e grãos detríticos impossibilitou sua separação visando a aplicação do método convencional 40K- 40Ar. Assim, optou-se em aplicar o método 40 39 Ar- Ar diretamente nos crescimentos autigênicos de K-feldspato. Como resultado, foi obtida uma idade mínima de 120 Ma, muito próxima à idade bioestratigráfica previamente estabelecida para os arenitos da Formação Açu, o que demonstra a viabilidade da aplicação do método 40Ar- 39Ar na determinação de idades deposicionais de arenitos-reservatório. Entretanto, para fins de aprimoramento do método e melhor precisão nas idades, é sugerido o uso de equipamentos que utilizam sonda a laser ultravioleta (UV), o que reduz a possibilidade de contaminação por diferentes fases minerais.

O depósito de bentonita da região de Bañado de Medina, situado 18 km a sudoeste da localidade de Melo, no Uruguai, constitui a primeira ocorrência na região com potencial para exploração comercial. O objetivo deste trabalho é apresentar dados referentes à mineralogia, composição química, tipos de contaminantes e fatores de controle dos depósitos, bem como algumas propriedades tecnológicas deste material. Com base em 31 furos de sondagem, foi possível a delimitação de uma camada de bentonita que localizadamente possui uma espessura de até 6,6m. A descrição dos furos, juntamente com trabalhos de campo, permitiu estabelecer um depósito de bentonita limitado inferior e superiormente por camadas de arenito dentro da Formação Rio do Rasto (Permiano Superior da Bacia do Paraná). O depósito foi protegido dos processos erosivos posteriores num bloco tectonicamente rebaixado, definido regionalmente por estruturas tectônicas antigas do embasamento com direções NE e NW. A reserva medida nos 9,5 ha de área prospectados é de 580.000 t, sendo formada por uma camada contínua de bentonita com cobertura de arenito/siltito da ordem de 1,60m até 11,60m de espessura. A bentonita Bañado de Medina resulta dos eventos finais do Membro Serrinha da Formação Rio do Rasto (Membro Vila Viñoles da Formação Yaguari, na nomenclatura uruguaia). De acordo com a textura, estruturas sedimentares e cor, a camada de bentonita foi dividida em quatro unidades. A determinação da mineralogia por difratometria de Raios-X mostra a predominância de esmectita dioctaédrica cálcica seguida de quartzo e feldspato, por vezes como minerais traços. Os resultados químicos indicam uma esmectita com baixo teor em Fe3+ e com cerca de 76% da carga interfoliar proveniente da substituição em nível octaédrico de Al3+ por Mg2+, classificando-se como uma Al-montmorilonita. Foi avaliada a capacidade de troca de cátions (valores medidos entre 101 e 116 meq/100g) e sua relação com domínios 2EG, 1EG e 0EG. A montmorilonita com grande predominância é a do tipo baixa carga (2EG). Seu uso tecnológico foi testado para aplicação em moldes de fundição e como fluido de perfuração. Os resultados apontaram índices adequados de estabilidade térmica, inchamento e resistência à tração a úmido, quando ativada com 5% de carbonato de sódio, The bentonite deposit found in the region of Bañado de Medina, 18 km southwest of the locality of Melo, in Uruguay, is the first one of commercial potential in that region. The aim of this work is to present mineralogy, chemical composition, types of contaminants and factors that control the deposits and technological properties of the bentonite. A promising exploration block was defined based on 31 boreholes, resulting in the delimitation of a bentonite bed that is locally 6.6 m thick. Field studies and borehole analysis have enabled the recognition of a bentonite deposit enclosed by sandstone beds in the sedimentary sequence of the Rio do Rasto Formation (Upper Permian of Paraná Basin). Such deposit was protected against subsequent erosion in tectonically depressed blocks, defined regionally by old basement, NE- and NW-trending tectonic structures. The reserve measured in the 9.5 ha area of the prospected block was estimated to be 580,000 tons, formed by a continuous bentonite bed with 1.60 m to 11.60 m thick sandstone/siltstone cover. The Bañado de Medina bentonite represents the final events of the Serrinha Member from the Rio do Rasto Formation (Vila Viñoles Member from the Yaguari Formation, in the equivalent Uruguayan nomenclature). According to texture, sedimentary structures and color criteria, the bentonite bed was divided in four units. Mineralogy evaluated by X-ray diffraction shows the predominance of dioctahedral calcium smectite followed by quartz and feldspar, sometimes as trace minerals. The chemical analyses indicate a smectite of low Fe3+ content and 76% of interfoliar charge, mainly associated to octahedral replacement of Al3+ by Mg2+, classified as Al-montmorillonite. The cation exchange capacity (measured values between 101 and 116 meq/100g) was evaluated in relation to 2EG, 1EG and 0EG domains. The montmorillonite is predominantly of the low charge type (2EG). Technological uses for foundry and drilling fluid were tested. The results indicate adequate thermal stability, good swelling properties and green strength when the bentonite is treated with 5% sodium carbonate.

The marl-limestone succession that encompasses the Pliensbachian–Toarcian Stage Boundary (Lower Jurassic) and crops out at Peniche (Lusitanian Basin, Portugal), was chosen as one of the candidates for the establishment of Toarcian GSSP. Chemostratigraphy analyses, of the Upper Pliensbachian (spinatum Zone)-Lower Toarcian (levisoni p.p. Zone) portion, were based on total organic carbon (TOC) (68 samples), the isotope carbon (δ13C) and oxygen (δ18O) (38 samples) on the whole rock sample. Presenting an absolute variation of around -2.0‰, the δ13C and δ18O values decrease from the middle part up to the uppermost part of spinatum Zone, with smaller values in the lowermost part of the polymorphum Zone. In the Lower Toarcian the δ13C data shows a positive trend (spread of + 2.0‰) with a maximum value in the middle-upper portion of the polymorphum Zone and a minimum in the lowermost part of the levisoni Zone. The δ18O values show a general tendency to decrease within the polymorphum Zone, with the smallest values observed in the lower portion of the levisoni Zone. In general the TOC values are low, around 0.2%, in the spinatum Zone, upwards they increase to 0.5% in the polymorphum Zone, whilst they decrease again to 0.2% in the lowermost levisoni Zone. Calcareous nannofossils assemblages were investigated in 12 slides of marly samples collected around the Pliensbachian – Toarcian Stage Boundary that, according to the adopted zonation, proposed for NW European, lies in the NJ5b biozone. Abundant and well preserved nannofossils assemblages comprise 12 genera and 18 species. The genera Schizosphaerella and Lotharingius are dominant. Calcivascularis jansae, a characteristic taxon of the Lower Jurassic tethyan nannofossils assemblages, is abundant in the whole investigated interval. Biscutum grande is the other tethyan taxon present in studied succession. The occurrences of C. jansae and B. grande support the tethyan affinity of the calcareous nannofossils assemblages recovered from the Pliensbachian – Toarcian transition sampled at Peniche section.

From statistical parameters of the bottom morphology and of the application of the diagram proposed by Pejrup(1988) it was possible to characterize the dynamic and sedimentary processes that occur in the estuary of the Marajó bay. The sediments that recover the bottom of the studied area are formed by medium to very fine sands that grade to coarse to fine silt in direction to the continental shelf. The hydrodynamic of the area is dominated by the tidal and fluvial currents as well, partly due the action of winds which influence these currents. These factors associated with the estuarine circulation, are responsible for the transport, redistribution and deposition of the sediments in the study area.

The Paulo Lopes Suite (SPL), composed of the Paulo Lopes Granite (GPL), Garopaba Granitoids (GG) and Silveira Gabbro (GS), is an association of contemporaneous acid and basic rocks, comprising monzo and syenogranites associated to basic dikes, with abundant mafic microgranular enclaves, interpreted as co-mingling products. The contacts between the granitoids and the basic rocks are evidences of coeval and interactive magmas. The Silveira Gabbro occurs in the study area as a main body and several narrow dikes of NNE orientation. Field relations define a chronological order of magmatic events, where the GPL is the first magmatic pulse and, while steel partially crystallized, was intruded by mingled magmas, represented by the GG and the GS. The basic components are medium-grained, equigranular rocks, with subophitic and ophitic textures. The centre of the main body contains medium- to coarse-grained, equigranular rocks, where agglomerates of early-formed clinopyroxene and plagioclase crystals are found. In the chilled margins, they are microporphyritc rocks of aphanitic groundmass, indicative of rapid crystallization. The Silveira Gabbro rocks are composed of labradorite-andesine, orthopyroxene, augite, pigeonite, olivine (occasionally serpentinized), Fe-hornblende and magnesian hornblende, red biotite, magnetite, ilmenite, apatite, and baddeleyite. The composition is tholeiitic, similar to the high-Ti-P basalts of the Serra Geral Formation. Their high contents of K, Rb, Sr and Ba, as well as negative anomalies of Nb and Ta in multielemental diagrams are similar to the ones observed in magmatic rocks from mature arcs or post-collisional environments. The Neoproterozoic basic rocks may be discriminated from the ones belonging to the Cretaceous Serra Geral Formation by their higher contents of alcalis, Cs, U, Th, and by their fractionated REEpatterns, expressed in the La/LuN ratio. The associated granitoids are structural and compositionally compatible with the ones found in post collisional settings, which indicates that the SPL magmatism developed in such environment.

The chemical composition of detrital minerals in sediments has become a powerful tool for provenance studies, particularly in the last decades with the improvement of analytical techniques for mineral grains. Major and trace element contents of igneous and metamorphic minerals can reveal the characteristics of their original sources, mainly with respect to their geochemical affinity, geotectonic setting and the physical parameters that controlled their crystallization. The proportions of major elements in pyroxenes and amphiboles can be used for the identification of their igneous or metamorphic origin, for the definition of their magmatic affiliation, and for the discussion of the probable tectonic setting where they were generated. Metamorphic and igneous zircons can be distinguished by REE patterns or U and Th contents. Magmatic zircons from different geotectonic settings can show different concentrations of REE, Nb, Hf and Y. Magmatic garnets from granites typically show high Mn contents, and can be distinguished from metamorphic ones or from garnets of ultramafic rocks mainly through their major element composition. Compositional zoning of garnets are indicative of their metamorphic or igneous character. Magmatic, metamorphic and hydrothermal epidotes can be distinguished by their chemical composition, as well. Several other minerals, such as apatite, tourmaline, rutile, titanite, and feldspars can indicate, through their chemical composition, the probable rock that could have produced them. The integration of geochemical data on detrital minerals with other usual tools of sedimentary petrology is certainly the most efficient approach for investigating the provenance of sediments.

Gold prospects in the Aguapeí Folded Belt are situated in the southwestern portion of the Amazon Craton, within the Alto Guaporé Province, southwestern state of Mato Grosso. The mineralizations are mainly concentrated in the Pau-a-Pique Deposit (south), Lavrinha Region (central), and São Vicente Mine (north). Gold ore comprises quartz veins and disseminations in the low-grade metamorphic metassedimentary rocks from the Aguapeí Group. This stratigraphic unit was strongly deformed by the Sunsás-Aguapeí Orogeny (1.28-0.95 Ga). The Aguapeí gold deposits differ in their petrography, chemistry, structural aspects and age from world classic gold deposits associated with coarse clastic sedimentary sequences (Witwatersrand, Jacobina, Tarkwa, etc.). This study discusses the main differences between Aguapeí gold deposits and the classic worldwide deposits hosted by conglomerates, Gold prospects in the Aguapeí Folded Belt are situated in the southwestern portion of the Amazon Craton, within the Alto Guaporé Province, southwestern state of Mato Grosso. The mineralizations are mainly concentrated in the Pau-a-Pique Deposit (south), Lavrinha Region (central), and São Vicente Mine (north). Gold ore comprises quartz veins and disseminations in the low-grade metamorphic metassedimentary rocks from the Aguapeí Group. This stratigraphic unit was strongly deformed by the Sunsás-Aguapeí Orogeny (1.28-0.95 Ga). The Aguapeí gold deposits differ in their petrography, chemistry, structural aspects and age from world classic gold deposits associated with coarse clastic sedimentary sequences (Witwatersrand, Jacobina, Tarkwa, etc.). This study discusses the main differences between Aguapeí gold deposits and the classic worldwide deposits hosted by conglomerates.

This paper aims the identification of the translucent heavy minerals that occur in the pedological covering at the northwestern region Paraná state (Brazil), and compare them to the minerals observed in the Caiuá sandstone that orverlies it. The origin of the pedological covering is controversial because many researches consider it to be colluvium, originated during a semi-arid climate that occurred in the Quaternary. To reach the proposed goals, morphological descriptions along the top sequences were done and samples from different profiles of the trenches were collected. A slight mineralogical diversity was observed at the pedological covering and at the Caiuá sandstone, where the main minerals are staurolite, rutile, tourmaline and zircon, followed by lower amounts of garnet, kyanite and dumortierite. This assemblage of minerals suggests a high textural and mineral maturity of the studied materials. It is an important argument concerning the origin of the pedological covering, suggesting that it was derived from the alteration processes of the overlaying sandstone, thus, confirming the residual characteristics of said materials in northwestern Paraná state, This paper aims the identification of the translucent heavy minerals that occur in the pedological covering at the northwestern region Paraná state (Brazil), and compare them to the minerals observed in the Caiuá sandstone that orverlies it. The origin of the pedological covering is controversial because many researches consider it to be colluvium, originated during a semi-arid climate that occurred in the Quaternary. To reach the proposed goals, morphological descriptions along the top sequences were done and samples from different profiles of the trenches were collected. A slight mineralogical diversity was observed at the pedological covering and at the Caiuá sandstone, where the main minerals are staurolite, rutile, tourmaline and zircon, followed by lower amounts of garnet, kyanite and dumortierite. This assemblage of minerals suggests a high textural and mineral maturity of the studied materials. It is an important argument concerning the origin of the pedological covering, suggesting that it was derived from the alteration processes of the overlaying sandstone, thus, confirming the residual characteristics of said materials in northwestern Paraná state.

Small format vertical aerial photographs were obtained from non metric cameras on small size airplanes, in 1999, and aimed to update a set of six digital cadastral maps from 1984, in the scale of 1:5,000, covering the urban area of Gramado county, located at the northeast region of the Rio Grande do Sul state, Brazil. The photographs were digitized, stored and georeferenced in a Geographic Information System. Afterwards, the perimeters of the new buildings and the boundaries of the urban area districts were digitized on the digital cadastral maps. The updated data of the cadastral maps were elaborated with the purpose to generate thematic analysis and can´t be used for the accurated measure of the mapped buildings. The poligons of the buildings were topologicaly structured by application of GIS, allowing the automatic generation of a centroid to each mapped building. The database query allowed the evaluation of the total number and the localization of the centroids of the buildings, for both date studied. The recorded data were represented by thematic maps of urban occupation expantion, in the scale of 1:25,000. Based on the data obtained, a 164.6 % increase of the total number of buildings was observed, as well as the occupation expantion towards the SE region of the urban area, caused by the major growth of the secundary sector and the major number of new developments in the meridional urban area, that occurred during the past 15 years. Through the interpretation of geographical data, recommendations were proposed for the urban planning of Gramado county.

This paper presents a methodology for semi-automatic road extraction from digital images using active contour models or snakes. Snakes was proposed almost two decades ago, consisting in a parametric curve controlled by photometric and geometric constraints. This last ones generate internal forces that control the shape of the snakes curve. The photometric constraints generate external forces that attract the snakes curve to the selected feature, i.e., the road. As this snakes-based method is semi-automatic, firstly the operator must describe the road roughly using at least six seed points. From this initial position, the snakes curve moves around at each interation, stabilizing when it coincides with the road. This road extraction methodology was tested with digital aerial images of different resolution. The experimental results obtained with these images showed the method’s potential in accurate and reliable road extraction.

Coastal-eolian sabkha sandstones from different ages and basins show similar diagenetic patterns, which understanding is important for their evaluation as geochemical systems and as hydrocarbon reservoirs. The Carboniferous sandstones of the Juruá Formation (Solimões Basin) are one of the most important gas reservoirs of Brazil. The sandstones and interbedded mudrocks, evaporites and dolostones were deposited within a coastal sabkha environment with pervasive eolian reworking, under increasing marine influence, and hot and dry climate. Four stacked drying/wetting upward cycles were identified, with sabkha facies in the base overlain by eolian deposits, followed again by sabkha deposits, commonly eroded by the next cycle. Eolian dune and sandsheet sandstones are the best reservoirs. The diagenetic evolution and the relationships among diagenesis, depositional facies and stratigraphic unit boundaries show similarities with other coastal-eolian sabkha sandstones. The eodiagenesis is characterized by mechanical compaction, hematite and infiltrated clay coatings, framboidal pyrite, microcrystalline and blocky dolomite. Mesodiagenesis comprises chemical compaction, K-feldspar and quartz overgrowths, poikilotopic anhydrite, feldspar dissolution and albitization, illite and chlorite authigenesis, and late quartz, Fedolomite/ ankerite, calcite and siderite. Localized telogenetic effects include oxidation of ferroan constituents and kaolinite precipitation. Blocky dolomite and quartz cementation, and chemical compaction through intergranular and stylolitic pressure dissolution are more abundant in the non-eolian sandstones. Microcrystalline pore-filling and pore-lining dolomite, and patchy, poikilotopic, post-compactional anhydrite cementation, mostly close to the contacts with interbedded evaporites, are more abundant in the eolian sandstones. These diagenetic patterns are similar to those of the Rotliegend Group in northern Germany and in the North Sea, of the Norphlet and Tensleep Formations in USA, of the Muschelkalk Formation in Spain, and of the Monte Alegre Formation from the Amazonas Basin, northern Brazil. The similarities among the diagenetic histories of these coastal-eolian sabkha sandstones are ascribed to their similar patterns of stratigraphic organization (intercalated evaporite and carbonate beds) and of composition and circulation of pore fluids.

A new biozone - called Ictidosaur Assemblage Zone - is proposed to the Upper Triassic Caturrita Formation from Southern Brazil, based on the discovery of a distinct tetrapod association characterized by the presence of little non-mammalian cinodonts including Riograndia guaibensis, Brasilodon quadrangularis and Brasilitherium riograndensis. Besides, the advanced procolophonid Soturnia caliodon, the dinosaur Guaibasaurus candelariensis, the dicynodont Jachaleria candelariensis, indeterminated phytosaurs and sphenodontids were also found in this association. The new biozone overlies the Rhynchosaur Assemblage Zone and encloses the “Jachaleria Level” usually cited for these layers. Stratigraphical sections, as well as facies analysis, facies associations and architectural elements confirms that the new biozone is clearly included in a distinct stratigraphical level, which reflects a marked change in the fluvial pattern of the sequence. The anastomosed/meandering pattern associated to the underlying Rhynchosaur Assemblage Zone turns to a braided to low confinement fluvial system with unconfined flows. The faunal and faciological changes may have been caused by a combined action of climatic, base level and floral changes, probably reflecting the global tendency to an increasing aridity towards the end of the Triassic. It is presumed an early Norian age for the new biozone on basis on its faunal content, on its stratigraphic placement, recovering the Carnian rhynchosaur assemblage and also on the presence of woods, leafs and reproductive structures of conifers, whose morphological pattern is exclusively Triassic.

The aim of this paper is to investigate by SEM the presence of crystalline forms of noble metals in dehydrated tissues of Scutia buxifolia (Rhamnaceae), Scoparia montevidensis (Scrophulariaceae) and Adiantopsis cf. chlorophylla (Pteridaceae), a endemic vegetation on ultramafic soils from Pedras Pretas, São Sepé, southermost Brazil. Chemical composition of rocks, soils and ash plants were also determined by ICP-MS. The rocks and soils from Pedras Pretas show the expected geochemical pattern of ultramafic ones. Despite the low concentrations of some trace elements and noble metals in ash plants, the BSE images obtained by electron microprobe reveal the presence of semicrystals of Au, Pt, and Ag, besides Ni, Cr, Fe and Ca in xilem parenchyma cells from the species concerned. These preliminary data show the necessity of combination of mineralogical with biogeochemical and physiological investigations in order to demonstrate the importance of these plants in forming biominerals. Moreover, studies about metallic concentrations in plant tissues can contribute to the comprehension of detoxication mechanisms of plants that can be applied for phytoremediation purposes.

The evaluation of cartographic features (semi-) automatically extracted from digital images is of great importance in the context of the validation of computational algorithms for feature extraction. The general procedure to evaluate the geometrical quality of cartographic features is based on the comparison between the entities extracted via computational algorithms and the corresponding ones extracted manually, the latter being referred to as reference features. Such comparison between the two groups of features is performed in three steps, i.e.: (1) calculation of corresponding points between the extracted features and the reference features; (2) estimation of quality parameters (completeness, correctness, quality, mean error (RM) and root mean squared (RMSE)) based on the corresponding points; and (3) analysis involving the quality parameters obtained in step 2. The evaluation methodology was tested in many situations, involving different image data as well as extraction methodologies with different characteristics. The results show that the methodology enables a very detailed evaluation of the results regarding the extraction methods.

Five types of paleo-weathering and carbonate precipitation were recognized in fine-grained deposits of the Alemoa Member, Santa Maria Formation, Middle to Upper Triassic of southern Brazil. The fauna and flora found in these lithologies are important dating tools, but only in a generic way, misleading the time involved in periods of deposition and non deposition. The identified types of deposits are (i) reddish mudstones, with none or little paleo-weathering, (ii) mottled mudstones, with incipient pedogenesis, mainly mottling, destratification, animal and vegetal colonization, (iii) carbonate veins, with more evidences of exposure and root action, (iv) carbonate siltstones/sandstones, where restricted fluvial deposits are cemented by phreatic carbonate, and (v) carbonate nodules and lenses, in which small lenses of a very compact calcrete are at the top and in the center of carbonated siltstone/sandstone beds, distinguished by its crystalinity, hardness and brighter color. The recorded microfacies point to a cyclic variation of the mainly high phreatic level, forming cracks and pedotubules (pedogenesis) filled with carbonate and Fe and Mn oxides (phreatic). The identification of five distinct pedofacies and the stratigraphic correlation in the sedimentary package of the Alemoa Member (base, middle or topmost position) suggest a probable association of paleo-weathering processes and vertebrate preservation. Near channel facies, mainly at the base and top, present smaller exposure periods and higher variations on the phreatic level, and consequently, the best preserved vertebrate fossils. On the other hand, facies which are far from the channel, record more subaerial exposure and more significant phreatic variation, leading to more advanced (although still incipient) paleo-weathering and carbonate precipitation, and to a worst fossil preservation.

This paper presents the results of a study performed on bedload samples from the Salso Creek in the Porto Alegre City (Rio Grande do Sul State) rural area where agricultural and pastoral activities are carried out within urban areas. Sediment sampling took place on the 16th September 2001 (winter) and 21th January 2002 (summer), at five sites along the Salso Creek. The Salso Creek bed load changes from granules and pebbles (upstream reaches), through coarse- to medium-grained sand (mid reaches) to fine-to very fine-grained sand in the Salso Creek mouth region. Organic matter content increases throughout the summer low discharge due to the accumulation of the suspended load on the creek bed surface. Grains larger then 0.062 mm feature the following estimated mineralogical composition: feldspar (55-50%), quartz (30-40%), opaque (5-10%) and acessory (5-10%) minerals. Among the finegrained sediments (< 0.062 mm) kaolinite dominates being followed by a minor amount of muscovite/illite as well as quartz, feldspar and smectite traces. The chemical composition of the fine-grained sediments reveals that, among the major (Al, Fe, Mn, Ca, Mg, Na and K) and trace (Cr, Cu, Ni, Pb and Zn) analyzed elements, the Al content is high, probably a result of the kaolinite-rich (Al4(Si4O10)(OH)8) composition of the fine-grained fraction. GeoAccumulation Index calculation shows no significant accumulation of any of the analyzed elements within the finegrained fraction, hence indicating slightly to moderately polluted sediments. On the other hand Contamination Factor computation for the sediments fine-grained fraction pointed out a Cu, Ni and Zn enrichment, indicating considerable to high contamination, especially for those places directly under domestic sewerage influence. These elements are probably being concentrated in the fine-grained fraction of the bed load.

This work presents the results of a high-resolution seismic reflection data survey carried out in the Patos lagoon inlet, near Rio Grande the southernmost harbor of Brazil. The analysis of the reflection patterns reveals the presence of transgressive/regressive barrier structures and beach/foredune-ridges. The mapping of these barrier structures allows a better understanding of the geological evolution of the Patos lagoon system during the Quaternary period and also helps to understand the evolution and migration of the actual lagoonal inlet between the Patos lagoon and Atlantic Ocean. Fil: Stalliviere Corrêa, Iran Carlos. Universidade Federal do Rio Grande do Sul; Brasil Fil: Aliotta, Salvador. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina Fil: Weschenfelder, Jair. Universidade Federal do Rio Grande do Sul; Brasil

The analysis of geomorphic and sedimentological characteristics of the inner continental shelf is an important propriety to studies of the coastal zone since they inform the conditions of the sea bottom, the predominant features and the types of associated sediments. Associated to morfodinamic study it can, for example, identify predisposed areas to erosive processes. The present paper shows the batimetry (to -20m) and the sediments distribution in the inner continental shelf between Porto de Galinhas and Campos beaches, south coast of Pernambuco State. The work results constitute pioneering mark in the inner continental shelf of the Pernambuco state.

This paper describes the bivalve Modiolopsis (?) clarkei n. sp, coming from the Curva I outcrop, Ponta Grossa Formation. The species name was given in honor to J. M. Clarke, who first studied it. This fossil also occurs in the Durazno Group, in Uruguay, reinforcing the correlation between the Devonian Paraná Basin invertebrate fauna with others of the Malvinocaffrik Realm, as suggested by previous authors. The classification of M. (?) clarkei in a typical Ordovician genus or lineage, that can reach the Silurian and Lower Devonian periods, supports an Emsian age to the Curva I outcrop, as have been accepted.

This paper deals with some aspects which should be taken into account for the densification of geodetic network using GPS technology, specially in the concern of Earth body tide modes, ambiguity resolution and the variance propagation of the network constrains. Based on trials accomplished for a GPS network, some aspects of GPS network optimization and processing are presented. In network optimization, applied to GPS networks, are presented the Zero Order, First Order and Second Order Problems, showing the needs of planning the GPS observations and processing in such a way that one can reach the required accuracy with high reliability and low costs. In the tests to evaluate the need for applying Earth body tide model, it was verified that it is necessary for baselines longer than 200 km for the majority of network application. It was noticed that the ambiguity solution should always be analyzed before accepting a fixed solution as the best, since the presented results demonstrated that some fixed ambiguities are inconsistent. In the processing trials with fixed constrains (without taken into account the precision) or fiducial constrains (with associated precision), it was noticed that the former provided better dispersion values for the new points, however, the last one provided more reliable values, since the new points have associated with themselves the uncertainty of the datum points.

The Rb-Sr and Sm-Nd isotopic systems are ideal in constraining the provenance of fine-grained clastic rocks. This is particularly true for continental, fluvio-lacustrine, sedimentary units deposited under semi-arid climate conditions, where mechanical desintegration of source rocks dominates the weathering processes. Three sets of red-colored, continental siltstones of the Camaquã Group (Early Paleozoic, southern Brazil) were analyzed for these isotopic systems, providing important data for the understanding of the provenance pattern of the Santa Bárbara (lower) and Guaritas (upper) formations. The results of six samples from the finer-grained portion of Sequence I of Santa Bárbara Formation (SEI samples) suggest provenance predominantly from the adjacent volcanic units (Hilário and Acampamento Velho formations), with subordinated contribution of monzonites (Arroio do Jaques) and metamorphic rocks (Cambaizinho), reflecting eastward paleoflow. Three samples from the outcrop area of the Santa Bárbara Formation east of Caçapava do Sul (SBG samples) reveal a similar provenance pattern, with a more effective contribution of felsic ignimbrites of the Acampamento Velho Formation as source rock. On the other hand, eight samples from the Guaritas Formation, obtained near Santana da Boa Vista (GUA samples), show anomalously high 87Rb/86Sr and 87Sr/86Sr ratios, suggesting more potassic source rocks. The values find correspondence mainly in the syn-transcurrent metagranites Quitéria, Arroio Francisquinho and Cordilheira (older than 600Ma), felsic lavas of the Acampamento Velho Formation (poorly exposed in the area), orogenic (Pinheiro Machado) and post-orogenic (Encruzilhada do Sul) intrusive suites. Other presently exposed units, such as the Encantadas Gneiss (older and more mafic) and the Porongos metasedimentary rocks (also older Nd signature) would have been buried or unavailable for erosion during the deposition of the Guaritas samples.

This paper presents results of SEM and EDS study in some Brazilian gemstones. Emerald from Campos Verdes (GO) contains several mineral inclusions as talc, dolomite, chromite, pyrite, magnetite, etc. Sylvite crystals was firstly identified by SEM/EDS. These salt inclusions suggest percolation of K-bearing fluids during emerald crystallization. Emerald from Campos Verdes present higher concentration of Cr+3 in the outer green zones than in the inner colourless zones, showing that ion is a chromophore in this gemstone. SEM and EDS results combined with optical microscopy analyses demonstrate that amethyst from Rio Grande do Sul State (RS) contain needle-like inclusions of goethite and not cacoxenite and rutile as suggest by other workers. By these techniques it was possible to identify pyrolusite and hollandite as late minerals inside agate and quartz geodes from RS. SEM and EDS data of corundum from Barra Velha (SC) show that silk effect is produced by diaspore inclusions. These techniques also reveal that the asterism in this corundum is produced by empty needle-like channels instead of the presence rutile inclusions as commonly observed in other worldwide deposits. Rounded zircon inclusions are common in corundum from Indaiá, Palmeiras, Caputira and Campo Belo (MG). Sillimanite and/or kyanite inclusions in corundum crystals of secondary deposits from Indaiá suggest a metamorphic origin to this gemstone. Corundum from Caputira also contains several rounded rutile inclusions, which are diagnostic for this occurrence.

Fossil mammals and reptiles were found at the basal conglomeratic level from the Salatiel II outcrop, Sanga da Cruz, Alegrete, Rio Grande do Sul, which gave an approximate thermoluminescence age of 14.000 years BP (before present). The fossil herein studied consists of a left dentary fragment of a horse, identified from the occlusal teeth surface as Hippidion cf. Hippidion principale. A preliminary analysis of the associated fauna permits to achieve some paleoclimate inferences for the region, presumably colder than the present.

The Mina da Palma oceanic plateau is described for the first time in the São Gabriel Block, southern Brazilian Shield. It is composed mostly of metabasalts, marbles and metachert. Two deformational events are recognized in the Palma region, thrust faulting followed by dextral subvertical shearing. The rocks were metamorphosed in the greenschist facies, as shown by the dominant mineral assemblage albite-actinolite-chlorite-epidote-opaques. Metamorphic alteration was intense, because only a few relicts of the original magmatic textures are preserved, such as flow structure of amphibole and plagioclase. In spite of intense alteration during metamorphism, geochemical studies show that the chemical composition of many basalts is still preserved. The metabasalts are transitional tholeiite/alkaline and reflect intraplate conditions of formation. The tectonic environment was identified by field relations, such as predominance of basalts and small volume of marble and chert and minor clastic sedimentary rocks. The tectonic environment of formation is reflected in the geochemistry, particularly in multi-element spidergrams, because no significant Nb anomaly is observed in the least altered samples.Previous investigations showed the presence of an island-arc basaltic-andesitic association in the Palma region, which indicated that the geological unit contains one oceanic association and one active plate margin association. This is possibly the first description of remnants of an oceanic plateau in the Brazilian Shield.

Carbon isotope ratios for carbonaceous material in the graphite prospect of Marmeleiro Sequence, southwestern of the Sul-rio-grandense Shield, have been determined. The results are approximately constant with δ13C-values between -27 and -24 per mil. These values suggest that the studied carbonaceous rocks were formed from syngenetic organic detritus, which were converted to graphite during metamorphism. The degree of cristallinity of carbonaceous material has also been investigated. The results of X-ray diffraction [d(002): 3.35 - 3.37 Å] indicate this material cristallinity is intermediate between amorphous carbon and fully ordered graphite.

Waimirite and Atroarite are associated with the core of the albite-granite from the Madeira Granite and occur in different places as thin veins. Waimirite is a yttrium fluoride that macroscopically form massive and white rounded aggregates. Atroarite is a alumino-fluoride and macroscopically form dark grey octahedral crystals. The DRX analyses confirm that they are new minerals.

Monazite structural group includes arsenates, phosphates, and silicates, with general formulae A B O4 , (A = Bi, Ca, Rare Earth Elements, Th, U and B = As5+, P5+, Si4+). Among them, the phosphate monazite is the most abundant independent Rare Earth Element mineral, occurring in several geological sites. It presents a variable composition and morphology and has strong chemical and physical stability. This paper presents a review about this mineral, particularly for monazite associated with carbonatite complexes. Detailed study of the composition of monazite will improve geochemical and petrological interpretations. In the economic field, monazite is, with bastnaesite, an ore mineral present in the main deposits in the world; its morphological and composition characteristics have influence in ore quality and in efficiency of concentration processes. Since the seventhies, its importance reachs the environmental field and his highly stable structure has been investigated as model for a synthetic phase to long-term storage of radionuclides from nuclear waste. The most important monazite ore deposits in Brazil are alluvional. Monazite occurs also in other materials, mainly in carbonatites and their weathering products, which may constitute important source of REE. In these rocks, because its high stability and possibility of weathering genesis, monazite is the most important among the phosphate minerals. However, researches about monazite associated with Brazilian carbonatitic materials have shown mainly unfavourable morphological characteristics for economic profit.

Water depth and substrate grain size composition were measured in a riffle-pool unit in the Guavirá stream, municipal district of Marechal Cândido Rondon, western region of Paraná State, Brazil. The objective of the work was to describe the effects of the floods on stream bed topography and sedimentological characteristics of the bottom sediments. During the first survey (December 2000, dry period), the sediment of bottom corresponds to granule and the mean elevation of the bed was of 314,382 m. With the occurrence of the precipitations in January and February 2001, the floods caused oscillations in the bed surface heights (314,177 m in the 2th and 314,403 m in the 3th surveys respectively) and the mean size of the bottom sediments had a continuous decrease: very coarse sand to coarse sand. The oscillation of the bed topography during the rainy period demonstrates that the velocity reversal of the flow during the inundations constantly migrate, fact that can explain erosion and deposition in a same reach during consecutive floods. In spite of bed elevation and sedimentological changes were observed in the riffle-pool unit, any longitudinal migration of the features was not verified even with the occurrence of floods exceeding the bankfull level.

Volcanic deposits can be included in two main groups: coherent and volcaniclastic. The former results from volcanic and sub-volcanic (syn-volcanic intrusions) effusive events, excluding autoclastic portions, and the second group, which is related to deposits constituted by volcanic fragments, encompassing primary deposits (pyroclastic) generated from fragment dispersion through gases and hot vapour, syn-eruptive resedimented deposits, besides volcanogenic sedimentary deposits. Clast transport processes are separated in three broad categories: mass-flow, traction and suspension. Basic concepts that are used in the study of volcanic rocks, classification and characterization of the main subaerial pyroclastic deposits are discussed in this paper, considering lithological and genetic aspects. Lithological aspects are mainly related to composition, components and grain-size of the deposits, while genetic aspects and interpretations are based on clast-forming and depositional processes, allowing understanding about eruption and emplacement conditions. Emphasis is given to pumiceous pyroclastic flow deposits, describing their main textural features and the post-depositional modifications associated to them. The discussed concepts are applied in the reconstruction of the Neoproterozoic pyroclastic flow deposits of two plateaus in the Sul-rio-grandense Shield, southernmost Brazil. The main characteristic of the Taquarembo Plateau is the occurrence of stratified/partially welded ignimbrites and high-grade welded deposits, while massive and crystal-rich ignimbrites are more common in the Ramada Plateau. The facies association of both plateaus suggests a fissural volcanic regime in a subaerial setting, associated to the post-collisional stages of the Brasiliano-Pan African Orogenic Cicle.

During June 1997, bottom sediment samples were collected at 76 stations on a rectangular grid in a small port (Lirquén Harbor, south-central Chile) facing siltation problems. The spatial changes in grain-size parameters, analyzed by using three different methodologies to infer net sediment transport paths, are compared with the measured water circulation of the study area and sediment dispersal patterns on aerial photographs. A Geographical Information System (GIS) is used to determine the degree of similarity between the results of the three grain-size trend methodologies. The results of this study confirm that because of its formulation and underlying assumptions, the McLaren-Bowles methodology tends to confuse the space-scale of sediment transport processes. In this way, the obtained transport patterns are in poor correlation with the observed hydrodynamics and aerial photographs and they seem to represent a combination of the spatial macroscale and mesoscale sediment transport processes existing in Concepcion Bay and in Lirquén Harbor, respectively. On the contrary, because the results yielded by the Gao-Collins and Le Roux methodologies correlate well with these studies, it is suggested that both methodologies be applied in combination to allow a better representation of local net sediment transport patterns, especially in estuarine environments where multiple sediment sources exist. Spatial analysis suggests that transport pathways obtained through these two methodologies represent the mesoscale sediment circulation existing in Lirquén Harbor. This study also emphasizes the importance of applying a statistical test to the transport trend vectors obtained using the GSTA program of Gao (1996), as these may erroneously reflect sediment transport direction. Lastly, the analyzed data and the results of the models are combined to determine the sediment transport regime existing in Lirquén Harbor.

This article presents a methodology for 3D visualization of a digital image and discusses its cartographic potential. Assuming that a regular DTM (Digital Terrain Model) is available, whose points are connected to form a triangular mesh, a shading methodology is applied triangle-by-triangle. This requires the computation of gray levels of image points corresponding to the pixels of 3D visualization plane, what in turn requires the modeling of the sensor used to acquire the image. Next, a shading model may be used to add artificially an extra effect of shading to the gray levels previously obtained, generating, e.g., shadows along the most elevated slopes opposed to the artificial light source. Finally, a projection model is used to obtain the 3D perception on the visualization plane. Results obtained were sufficient, showing that the 3D visualization methodology has the potential to be used in several cartographic application, as, e.g., in the cartographic revision.

Geophysical (aeromagnetometry) and remote sensing (TM LANDSAT) data allowed to recognize different structural patterns at the Santa Catarina fluorite district. These features correspond to N-S and NNE-SSW structural lineaments with potential environments for fluorite prospection. In detail, the used treatment allowed to identificate minor structures associated with these lineaments and showed that two principal structures carring mineralization prolongs themselves for dozens of kilometers in areas where previous existence were not even suspected. So a serie of data were searched about origin, evolution and relative chronology for the structures present in several directions, just like questions about the geological evolution of the district.

Centimeter level GPS positioning is based on the very precise carrier beat phase measurements. However, this observable is ambiguous by a number of whole cycles between the satellite and receiver antenna at the first epoch of data collecting, which is called the ambiguity. GPS ambiguities are introduced as parameters to be estimated in the observation equations. However, since they are integer numbers there is no standard techniques for solve them. One of the ways is to apply sequential conditional least-squares estimation together with integer search techniques. The ambiguity resolution can be divided in two steps: estimation and validation. The estimation is concerned with the computation of the ambiguities values. The validation step is used to infer if the estimated value can be accepted or not. From the last decade until nowadays ambiguity resolution has been one of the most important research topic in geodetic positioning and a several methods have been proposed. Special attention has been made about the fast ambiguity resolution. The aim of this paper is to investigate the ambiguity resolution in the context of relative kinematic positioning and its implementation in the GPSeq software, which is a GPS data processing software developed in academic environment. In this paper some experiments about kinematic processing are presented, whose results shown that the GPSeq solution is compatible on the centimeter level with Reliance software. The results also shown an inefficiency of the ratio and the difference between the quadratic form of the residuals of the second best and best solution tests in validating the ambiguity resolution in time limits of solution of the baselines processed.

The gathering of geotechnical investigation by SPT and CPT follow geological and environmental criteria, identified in maps, allowed identify different units, influence zones of degree of maturity or geomorphological conditions, influence of fault zones and different alluvial areas, allowed to identify different behavior of ratio qc/N in soils of Porto Alegre city. This work presents the criteria utilized for this differentiation, showing the figures of correlation between qc and N, and figures showing the behavior of K (qc/N) related to the depth, with considerations about the results.