As relações entre tectonismo e seqüências deposiconais no rifte potiguar - porção SW do Graben de Umbuzeiro, bacia potiguar emersa

Through an integrated approach, using litho, chrono and biostratigraphic data, the relative importance of climate variations and tectonics were recognized in rift sediments of the onshore Potiguar Basin, Northeast Brazil. Concepts of sequence stratigraphy were applied as a template to integrate sedimentological and geochemical data (oxygen isotopes), as well as quantitative palynologic methods to address and recognize the main depositional patterns produced in a rift basin. The main objective was to address the relative importance of climate changes and tectonics to the resultant stratigraphic architecture. The results of computer simulations of sedimentary basin fills of rift basins were quite useful to test working hypothesis and mimic the process of filling a half graben during a rift event. The studied section includes a neovalanginian-eobarremian (Lower Cretaceous) rift interval from the Pendência Formation, located in the southwestern portion of Umbuzeiro Graben, in the offshore Potiguar Basin. The depositional setting is interpreted as progradational deltaic system entering a lake from its flexural margin. Sismoestratigraphyc and well logs analyses allowed to interpret two regressive intervals (Green and Yellow Sequences), separated by a broad transgressive interval (Orange Sequence), known as the Livramento Shale. The depositional history encompass three stages: two tectonically active phases, during the deposition of the Green and Yellow Sequences, and a tectonically quiescent phase, during the deposition of the Orange Sequence. Paleoclimatic interpretation, based on quantitative palynology and geochemical data (��18O), suggests a tendency to arid conditions during the tectonically active phases and wet conditions during the tectonically quiescent phase. Stratigraphic modeling and backstripping techniques, supported by paleoclimatic/paleoecologic interpretations provide a powerful methodology to evaluate the tectonic and climatic controls on tectonic lakes

Modelagem estrutural física de semigrábens ortogonais e oblíquos à distenção regional: influência da trama do embasamento e comparação com analógicos no nordeste brasileiro

The physical structural modeling tool is being increasingly used in geology to provide information about the evolutionary stages (nucleation, growth) and geometry of geological structures at various scales. During the simulations of extensional tectonics, modeling provides a better understanding of fault geometry and evolution of the tectonic-stratigraphic architecture of rift basins. In this study a sandbox type apparatus was used to study the nucleation and development of basins influenced by previous structures within the basement, variably oriented as regards to the main extensional axis. Two types of experiments were conducted in order to: (i) simulate the individual (independent) development of half-grabens oriented orthogonal or oblique to the extension direction; (ii) simulate the simultaneous development of such half-grabens, orthogonal or oblique to the extension direction. In both cases the same materials (sand mixed with gypsum) were used and the same boundary conditions were maintained. The results were compared with a natural analogue represented by the Rio do Peixe Basin (one of the eocretaceous interior basins of Northeast Brazil). The obtained models allowed to observe the development of segmented border faults with listric geometry, often forming relay ramps, and the development of inner basins faults that affect only the basal strata, like the ones observed in the seismic sections of the natural analogue. The results confirm the importance of basement tectonic heritage in the geometry of rift depocenters

Evolving Future Internet clean-slate Entity Title Architecture with quality-oriented control-plane extensions

A Internet atual vem sofrendo vários problemas em termos de escalabilidade, desempenho, mobilidade, etc., devido ao vertiginoso incremento no número de usuários e o surgimento de novos serviços com novas demandas, propiciando assim o nascimento da Internet do Futuro. Novas propostas sobre redes orientadas a conteúdo, como a arquitetura Entidade Titulo (ETArch), proveem novos serviços para este tipo de cenários, implementados sobre o paradigma de redes definidas por software. Contudo, o modelo de transporte do ETArch é equivalente ao modelo best-effort da Internet atual, e vem limitando a confiabilidade das suas comunicações. Neste trabalho, ETArch é redesenhado seguindo o paradigma do sobreaprovisionamento de recursos para conseguir uma alocação de recursos avançada integrada com OpenFlow. Como resultado, o framework SMART (Suporte de Sessões Móveis com Alta Demanda de Recursos de Transporte), permite que a rede defina semanticamente os requisitos qualitativos das sessões para assim gerenciar o controle de Qualidade de Serviço visando manter a melhor Qualidade de Experiência possível. A avaliação do planos de dados e de controle teve lugar na plataforma de testes na ilha do projeto OFELIA, mostrando o suporte de aplicações móveis multimídia com alta demanda de recursos de transporte com QoS e QoE garantidos através de um esquema de sinalização restrito em comparação com o ETArch legado

Arquitetura deposicional e evolução tectono-estratigráfica das sequências pré-rifte e rifte, na porção central do Vale do Cariri, Bacia do Araripe, NE do Brasil

A complex depositional history, related to Atlantic rifting, demonstrates the geological evolution during the late Jurassic and early Neocomian periods in the Araripe Basin NE Brazil. Based on outcrop, seismic and remote sensing data, a new model of the tectono-stratigraphic evolution of the section that covers the stages Dom João, Rio da Serra and Aratu (Brejo Santo, Missão Velha and Abaiara formations) is presented in this paper. In the stratigraphic section studied, ten sedimentary facies genetically linked to nine architectural elements were described, representing depositional systems associated with fluvial, aeolian and deltaic environments. Based on the relationship between the rates of creation of accommodation space and sediment influx (A / S) it was possible to associate these depositional systems with High and Low accommodation system tracks. These system tracks represent two tectono-sequences, separated by regional unconformities. The Tectono-sequence I, which includes lithotypes from the Brejo Santo Formation and is related to the pre-rift stage, is bounded at the base by the Paleozoic unconformity. This unit represents only a High Accommodation System Track, composed by a succession of pelitic levels interbedded with sandstones and limestones, from a large fluvial floodplain origin, developed under arid climatic conditions. The Tectono-sequence II, separated from the underlying unit by an erosional unconformity, is related to the rift stage, and is composed by the Missão Velha and Abaiara Formation lithotypes. Changes in depositional style that reflect variations in the A / S ratio, and the presence of hydroplastic deformation bands, make it possible to divide this tectonosequence into two internal sequences. Sequence IIA, which includes the lower portion of the Missão Velha Formation and sequence IIB, is composed by the upper section of the Missão Velha and Abaiara Formations The Sequence IIA below, composed only by the Low Accommodation System Track, includes crossbedding sandstones interbedded with massive mudstones, which are interpreted as deposits of sandy gravel beds wandering rivers. Sequence IIB, above, is more complex, showing a basal Low Accommodation System Track and a High Accommodation System Track at the top, separated by an expansion surface. The lower System Track, related to the upper portion of the Missão Velha Formation, is composed by a series of amalgamated channels, separated by erosion surfaces, interpreted as deposits of a belt of braided channels. The High Accommodation System Track, correlated with the Abaiara Unit, is marked by a significant increase in the A / S, resulting in the progradation of a system of braided river deltas with aeolic influence. Regarding tectonic evolution, the stratigraphic study indicates that the Tectonosequence Rift in the Araripe basin was developed in two phases: first characterized by a beginning of rifting, related to Sequence IIA, followed by a phase of syndepositional deformation, represented by sequence IIB. The first phase was not influenced by the development of large faults, but was influenced by a sharp and continuous decrease of accommodation space that permitted a change in depositional patterns, establishing a new depositional architecture. In turn, the stage of syndepositional deformation allowed for the generation of enough accommodation space for the preservation of fluvial-lacustrine deposits and conditioned the progradation of a braided river-dominated delta system.