Controles geologicos da carstificaçăo em metadolomitos da formaçăo Capiru - neoproterozoico, regiăo metropolitana de Curitiba, Parana /

Orientador : Prof. Dr. Jose Manoel dos Reis NetoCo-orientadores : Prof. Dr. Antonio Manuel de Almeida Rebelo, Prof. Dr. Nilo Siguehiro MatsudaDissertaçăo (mestrado) - Universidade Federal do Paraná, Setor de Setor de Ciencias da Terra, Programa de Pós-Graduaçao em Geologia. Defesa: Curitiba, 2007Inclui bibliografiaÁrea de concentraçăo: Geologia exploratori

Editorial: Exploring the geochemistry and biogeochemistry of modern and ancient sedimentary systems

Sedimentary rocks are our window to understand the history and evolution of the surface of our planet. The sedimentary record, although biased by variable preservation conditions and post depositional processes, potentially preserve signals of the interaction between physical, chemical and biological processes that takes place at the interface between the Geosphere, the Hydrosphere/ Atmosphere and the Lithosphere. Geochemistry, integrated with Sedimentology, has become a standard approach to unravel these interactions and to provide some insights for the understanding of how sedimentary geochemistry is preserved within different sedimentary environments. Microbial life is ubiquitous at the Earth’s surface (Whitman et al., 1998), and has been present throughout our Planet’s history. It has evolved to exploit the energy provided by gradients in geochemical composition between rocks, organic materials and surface fluids, using this energy for maintenance and growth (Hoeler, 2007). Due to their abundance, chemical reactivity and metabolic activity (Konhauser, 2007), microbes play a central role in biogeochemical cycles (C, O, N, S, Fe, etc) at both, micro and macroscopic scales (Schlesinger and Bernhardt, 2020). The best example of these processes are the current chemical composition of our O2-rich atmosphere or the chemical redox gradients that exist at the sediment-water interface in most sedimentary environments around the world, where early diagenesis driven by organic matter degradation takes place (Aller, 2014). In addition, microbial mats and biofilms influence the precipitation/dissolution of minerals such as carbonates (explaining the the abundance of microbialites in the ancient rock record, Riding, 2011) as well as the rheological and mechanical behaviour of detrital sediments, where a classic example are known as MISS (Microbially induced sedimentary structures, Noffke et al., 2010). For these reasons, whenever we talk about sedimentary geochemistry we are actually talking about sedimentary biogeochemistry and geomicrobiology. This is so since microbial activity has been shaping the surface chemistry and composition of our planet, as previously recognized by the pioneering work of Vladimir Vernadsky in 1926 and later by Lourens Baas-Becking in 1934 (Knoll et al., 2012). Vernadsky and Baas-Becking early ideas have grown and become the lens through which we scientifically observe our world, making it clear that the Biosphere adds another layer of diversity and complexity in order to understand our planet as a system

Registro da predação por microgastrópodes Heleobia australis em estromatólitos da Lagoa Salgada, Estado do Rio de Janeiro, Brasil

O presente trabalho objetivou caracterizar as carapaças de moluscos encontradas em estromatólitos da Lagoa Salgada, Rio de Janeiro, e compreender a relação e influência desses pequenos organismos com o desenvolvimento da bioestrutura na qual ocorrem. Uma amostra recente de estromatólito domal foi dividida da base para o topo em cinco fácies, sendo que na fácies trombólito tem-se a ocorrência pervasiva de bioclastos identificados como carapaças de microgastrópodes da espécie Heleobia australis. Foram coletados 500 exemplares de valvas de cor branca, às vezes translúcidas, e com brilho perolado, não apresentando sinais de tração ou arrasto, mas encontrando-se majoritariamente inteiras. As conchas variam em tamanhos de 1,0 mm até 4,0 mm de comprimento com diâmetros variando de 1,0 mm até 2,0 mm. Os exemplares de tamanhos diferentes ocorrem juntos nas cavidades dos estratos. Os ciclos de vida dos H. australis foram estimados por meio de análise da distribuição tamanho-frequência, na qual identificou-se uma população jovem com um provável ciclo de vida curto durante o desenvolvimento estromatolítico. A variação dos tamanhos das conchas encontradas, representando diferentes estágios de vida dos microgastrópodes, sugeriu que esses organismos não foram transportados e trapeados pelo estromatólito, mas viveram naquele ecossistema durante o desenvolvimento da estrutura estromatolítica, predando os microrganismos formadores do estromatólito. Os H. australis foram ainda responsáveis pela intensa bioerosão presente nessa amostra, culminando com o aumento da porosidade daquela fácies. Por fim, as valvas configuram uma das fontes de carbonato na Lagoa Salgada, devido à dissolução bioquímica ocasionada pela atividade microbiana

GEOQUÍMICA E PALINOLOGIA DE TUFAS CALCÁRIAS DA REGIÃO DE BONITO-MS. IMPLICAÇÕES AMBIENTAIS.

As tufas são rochas carbonáticas continentais precipitadas a partir de um fluido rico em bicarbonato com temperatura ambiente, comumente apresentam restos de micro e macrovegetais, invertebrados e bactérias. As tufas de Bonito (MS) ocorrem principalmente ao longo de drenagens, e estão relacionados com rochas subjacentes do Grupo Corumbá, sendo inseridas na Formação Serra da Bodoquena. O presente trabalho tem como objetivos: 1) compreender as condições físico-químicas do fluido; 2) identificar o ambiente deposicional; 3) correlacionar dados isotópicos e palinológicos para estudos paleoclimáticos. Foram realizadas descrições macro- e microscópicas, análises geoquímicas por DRX e FRX, análises isotópicas de Carbono e Oxigênio, e estudos palinológicos. As amostras foram coletadas sistematicamente em um afloramento no sítio Mimosa, no Membro Rio Formoso. Três fácies foram descritas: i) fitoherma, formada pelo acúmulo de folhas e fragmentos de plantas; ii) shrubs, estruturas fibro-radiadas; iii) estromatólitos, internamente laminados. Foram identificadas piscinas, barreiras e cascatas/cachoeiras como os principais ambientes deposicionais. A tendência negativa observada nos dados isotópicos indica um fluido meteórico e presença de atividade biológica. A presença em grandes quantidades de fungos e hifas, além de esporos de pteridófitas e grãos de pólen de angiospermas indicam um ambiente úmido e com vegetação abundante, típico de clima tropical

Disentangling microstructure and environmental conditions in high‐altitude Andean microbialite systems (Catamarca, Argentine Puna)

The study of microbialites development is a key tool to understand environmental pathways during deposition. We provide a detailed analysis of modern Central Andean microbialites from high-altitude lakes. The stratigraphic record of Turquesa Lake shows a significant short-term recolonization by microbialite-producing microorganisms during environmental stress. Far from a crisis paradigm, the coasts and paleocoasts of Turquesa lake exhibit three microbialitic buildups formed along different stages, providing a good study case of biological resilience of these systems in harsh environments. The MI and MII microbialite buildups occupied two paleocoasts. Both are composed of oncoids with micritic to microsparitic textures. Morphological, textural and mineralogical similarities between the two buildups suggest that they were formed at different times, but under very similar environmental conditions. The microorganisms that produced the microbialitic buildup MIII are currently colonizing the coast of this lake. The previous oncoid morphology change to a parallel micritic–spartic lamination. This remarkable changes in the microstructure can be explained by an important environmental change caused by the isolation of the Peinado Lake, and a subsequently microorganism adaptation. This microbialite structures can be proposed as an interesting modern analogue for environmental changes along the geological record.Fil: Della Vedova, Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Villafañe, Patricio Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Cónsole Gonella, Carlos Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Bahniuk Rumbelsperger, Anelize. Universidade Federal do Paraná; BrasilFil: Fadel Cury, Leonardo. Universidade Federal do Paraná; BrasilFil: Horta, Luis Rubén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentin

Conformational and constitutional analysis of dental caries following radiotherapy for head and neck cancer

BACKGROUND: This study aimed to investigate the morphology and chemical composition of dental caries related to ionizing radiation (DCIR), an aggressive and progressive disease that affects dental hard tissues. MATERIALS AND METHODS: Eight human teeth with DCIR were paired with sixteen control teeth (8 teeth with conventional caries and 8 without caries) and included in this study. An analysis of the morphology of the lesions was performed using the following techniques: periapical radiography, cone beam computed tomography, computed microtomography, and scanning electron microscopy. The chemical composition was assessed using X-ray dispersive spectroscopy. RESULTS: There was more demineralization in DCIR lesions when compared to conventional dental caries, even though there was no cavitation in the cervical region of the teeth. The superficial roughness and topography of DCIR lesions were similar to those of healthy teeth. On the other hand, lesions of conventional dental caries showed greater surface and topographic irregularity when compared to DCIR and healthy teeth (p = 0.001). Calcium (Ca) and phosphorus (P) levels were lower in DCIR lesions when compared to controls. However, higher levels of carbon (C) have been observed in DCIR lesions. There was a greater loss of the mineral matrix in DCIR followed by conventional caries. The reduction in the mineral matrix (Ca and P) was compatible with the imaging patterns observed in teeth with DCIR and conventional caries. CONCLUSION: Despite their rapid evolution, DCIR presents an irregular, apparently intact surface with significant changes in the amount of Ca, P, and C

Controles geologicos da carstificaçăo em metadolomitos da formaçăo Capiru - neoproterozoico, regiăo metropolitana de Curitiba, Parana /

Orientador : Prof. Dr. Jose Manoel dos Reis NetoCo-orientadores : Prof. Dr. Antonio Manuel de Almeida Rebelo, Prof. Dr. Nilo Siguehiro MatsudaDissertaçăo (mestrado) - Universidade Federal do Paraná, Setor de Setor de Ciencias da Terra, Programa de Pós-Graduaçao em Geologia. Defesa: Curitiba, 2007Inclui bibliografiaÁrea de concentraçăo: Geologia exploratori

Low-temperature metamorphism in the Capiru Formation, Morro Grande Synform, Southern Ribeira Belt

ABSTRACT: The Capiru Formation consists of a low-grade meta-sedimentary succession of slates, phyllites, quartzites and marbles, disposed in blocks delimited by thrust and strike-slip faults in the Curitiba Terrane, Southern Ribeira Belt, Southern Brazil. The metamorphic and deformation records are heterogeneous, with deformed zones tectonically interbedded by domains with preserved sedimentary features. The present work aims to understand the development of mineral paragenesis based on geochemical and petrographic analysis. We selected samples of metasandstones, slates, phyllites and rhythmic phyllites, with different metamorphic and deformation records to be analysed. We selected samples with different metamorphic records to be analysed. The petrographic characterization of foliations was made through field studies supported by microtectonic analysis. The mineralogical and chemical compositions were determined by X-ray diffractometry and X-ray fluorescence, respectively. The results show a preserved sedimentary bedding (S0), defined by sedimentary structures with top-and-bottom indicators. The S1 foliation is related to a thrust tectonics, and it is characterized by a continuous slaty cleavage. The S1 slaty cleavage is crenulated and cut by a millimetric S2 cleavage. The mineral assemblage is composed by quartz, sericite, magnetite/goethite and carbonaceous material. The metamorphism was developed under low-temperature conditions (between 250-350ºC) and low pressure gradients (2.5-4.5 kbar). The geotectonic environment is considered as a thrust-and-fold-belt system, with structures developed in superior crust levels