42 resultados para RIFT


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Paleogene sediments of this region represent a significant source of water for urban, industrial and agricultural activities. This basin is part of the Southeastern Brazilian Continental Rift, which occupies a large portion of this geographical area. This study aims to present the evolution of the natural Paleogene landscape, through an analysis of its stratigraphic intcrops and underground portions based on the concept of facies and facies associations. A total of nine clastic and separate lithofacies were recognized and grouped into two main facies associations. These data suggest the existence of two depositional interdigitated systems: fluvial braided fans, which were predominant in parts of the northern and central area, and another composed of lacustrine sediments found in its central-south region. The paleogeography herein outlined will help considerably in the detection of new areas for mineral and water resources prospection, as well as in urban planning projects of this region.

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The Equatorial Atlantic Margin evolved from three rift systems recorded by a complex set of sedimentary basins developed since Upper Triassic to the Lower Cretaceous (Albian). The first rift system formed Foz do Amazonas Basin in Upper Triassic; the second phase formed Marajó Basin in Berriasian, a new rift in Foz do Amazonas Basin in Valanginian and Bragança-Viseu, Ilha Nova, São Luís e Barreirinhas basins in Aptian; the third phase formed Barreirinhas and Pará- Maranhão basins and a new rifting in the Foz do Amazonas Basin between the Aptian and Albian and evolved to continental break up. The main paleostress field during rift evolution was NE-SW and after the continental break up took the E-W direction, from the development of transform zones in the oceanic crust. From Miocene, South America was subjected to intraplate tectonics, which resulted in formation of E-W transcurrent faults that generated transtensive and transpressive segments that formed sedimentary basins and hills, resulting in changes in the drainage network. In Quaternary the landscape was modified by the last ice age that changed the sea level; the coastal drainage network was drowning resulting in the formation of the current line coast.

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Dictyosperma album, commonly known as Princess Palm, due to its graceful appearance and its ability to withstand strong hurricane force winds is largely used in landscaping areas. The aim of this work was to describe the diaspores (seeds with the stuck endocarp) morphology and the stages of the D. album germination process. Therefore we concluded that the species germination is of the tubular remote type and begins with the opening of a circular operculum in the fruit endocarp, through which emerges a bulbous and hollow structure, named cotyledonal petiole or embryophore. With the embryo growth, the endosperm is being gradually consumed. The embryo grows approximately up to 10 cm, when the dilation begins in its extremity. Starting from this extensive area, it begins the growth of the primary root and the opening of a longitudinal rift, through which emerges the aerial part that is composed by two sheaths that cover the first juvenile leaf. In this phase, the emergence of secondary roots is observed. The first leaves are simple and lance-shaped.

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The area between São Paulo and Porto Alegre in southeastern Brazil plays a key area to understand and quantify the evolution of the South Atlantic passive continental margin (SAPCM) in Brazil. In this contribution, we present new thermochronological data attained by fission-track and (U-Th-Sm)/He analysis on apatites and zircons from metamorphic, sedimentary and intrusive rocks. The zircon fission-track ages range between 108.4 (15.0) and 539.9 (68.4). Ma, the zircon (U-Th-Sm)/He ages between 72.9 (5.8) and 525.1(2.4). Ma, whereas the apatite fission-track ages range between 40.0 (5.3) and 134.7 (8.0). Ma, and the apatite (U-Th-Sm)/He ages between 32.1 (1.5) and 93.0 (2.5). Ma. The spatial distribution of these ages shows three distinct blocks with a different evolution cut by old fracture zones. While the central block exhibits an old stable block, the Northern and especially the Southern block underwent complex post-rift exhumation. The sample of the Northern block shows two distinct cooling phases in the Upper Cretaceous and the Paleogene to Neogene. After sedimentation of the Permian sandstones the samples of the Central block were never heated up over 100. °C with a following moderate to fast cooling phase in Cretaceous to Eocene time and a fast cooling between Oligocene to Miocene. The five thermal models obtained in the Southern block indicate a complex evolution with three cooling phases. The exhumation events of the three blocks correspond with the Paraná-Etendekka event, the alkaline intrusions due to the Trinidad hotspot, and the evolution of the continental rift basins in SE Brazil and are, therefore, most likely to be the major force for the post-rift evolution of the passive continental margin in SE Brazil, which therefore corresponds to the three main phases of the Andean orogeny. © 2013 Elsevier B.V.

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Pós-graduação em Geologia Regional - IGCE

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pós-graduação em Estudos Literários - FCLAR

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Pós-graduação em Geociências e Meio Ambiente - IGCE

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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É feita uma análise da evolução dos conhecimentos sobre as coquinas-reservatório da Formação Lagoa Feia, com base em cinco publicações de geologia de desenvolvimento dos campos de Badejo, Linguado e Pampo. Trata-se de uma única acumulação, onde o controle é misto, ou seja, estrutural, estratigráfico e principalmente diagenético. Falhas antitéticas herdadas do rifteamento pós-basáltico exercem um importante papel no controle das coquinas, promovendo crescimento da seção nos blocos baixos, e servindo de conduto para a circulação de água meteórica, relacionada à discordância pós-coquina que promove dissolução e criação de porosidade secundária nas coquinas. A compreensão do modelo de acumulação do óleo é fundamental tendo em vista oportunidades para projetos de recuperação suplementar de óleo.