103 resultados para Atlántico Noreste
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Located in northeastern Brazil, the evolution of Araripe Basin has been associated with the fragmentation of Gondwana and opening of the South Atlantic. The Santana Formation belongs to the post-rift sequence of the basin and is characterized by the presence of laminated limestones in the lower portion (Mb. Crato), evaporite (Ipubi) and siliciclastics (Mb. Romualdo). For better understanding of the Romualdo's stratigraphy, depositional environments and tract of systems, a stratigraphic analysis was made with representative columnar sections of the unit. Sedimentary facies have been described in detail, as well as paleocurrents measured at different stratigraphic levels. It was found that the contact of Mb. Romualdo with the carbonate-evaporite section (Mbs. Crato and Ipubi) is a unconformity, evidenced by residual lags and thin layers of conglomerates above the contact. Above the conglomeratic levels predominate fine sandstones / medium interlayered with calciferous green shales. The percentage of shales increases towards the top, featuring retrogradational stacking culminating in layers of coquinas, excellent stratigraphic mark in the basin. Thin layers of coquins of gastropods comprising equinoids, located on the shale section, present in three sections marine deposits are associated with surfaces ravine. The upper section is characterized by recurrent facies of green shales, sandstones intercalated with sandstones progressively become more frequent towards the top of the unit, featuring the regressive part of the cycle. The sandstones present cross-stratification, often with mud clasts and clay layers in the foresets, and beddings of flaser type and wavy in heterolitic facies, suggesting the action of tidal currents. Paleocurrents measured in the sandstones show gaps with opposite flow directions outlining bipolar standards, which reinforce the interpretation of shallow marine environment influenced by tides during the sedimentation...
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The Areado Group of the Sanfranciscana Basin is a Lower Cretaceous continental sedimentary system that is correlated to the Brazilian Pre-Salt beds. The Aerado Group is composed of Abaeté, Quiricó and Três Barras formations. Paleocurrent data for the Areado Group were previously presented, although not systematically which prevented significative interpretations on the basin paleogeography. This work attempts to systematically evaluate paleocurrent data, aiming to recognize depositional environment and paleogeographic reconstruction, based on the sedimentary facies and paleocurrents measurements along vertical profiles. Fluvial paleocurrents of the Abaeté Formation indicate paleoflows towards NW whereas aeolian palecurrents of the Três Barras Formation show paleowinds towards SW. The depositional systems interpreted for the Areado Group were: braided river, alluvial fan, lacustrine, playa lake, fluvial-deltaic and aeolian. The combined analyses of facies and paleocurrents allowed a reliable paleogeographic reconstruction of the basin, with paleodip towards northwest, paleowinds towards south-southwest and source-area located at southeast. These results indicate that paleowinds were orthogonal to paleostream, but parallel to depositional strike of the basin. The interpreted depositional systems characterize a desert environment during the Abaeté sub-basin times. The association of dunes and wet interdunes followed by large scale dunes and dry interdunes suggests a decrease in humidity towards the top of the Três Barras Formation, with a dry aeolian system onlapping the basement. The observed decrease of humidity in Sanfranciscana Basin may reflect local or regional paleoclimatic changes during the opening of the South Atlantic, but this assumption is only tentative
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Pós-graduação em Geociências e Meio Ambiente - IGCE
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Brazil is a major importer in the world salted fish trade. The sale of these products must meet the established standards, based mainly on the salt and moisture levels. The aim of this study was to analyze the salt and moisture levels in imported Atlantic cod and Pacific cod, and in the dried salted fish Ling, Zarbo and Saithe, which are not classified as cod since they do not belong to the genus Gadus. The water activity was also analyzed, which could be a useful parameter to determine the quality of salted fish.The results showed that the legal limits for salt were much lower than the values found in the analyses. The moisture contents established for the category of salted fish, as determined by the Portuguese legislation, were more reliable. We suggest the inclusion of the water activity as a parameter for the evaluation of these products.
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Pós-graduação em Biociências - FCLAS
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Geociências e Meio Ambiente - IGCE
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Geociências e Meio Ambiente - IGCE
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Pós-graduação em Geociências e Meio Ambiente - IGCE