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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

AnÃlise textural e geoquÃmica dos argilominerais do talude continental do oeste do Cearà / Textural analisys and geochemistry of clay minerals from the contiental slope of western CearÃ

JoÃo Capistrano de Abreu Neto 19 September 2012 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Esta pesquisa foi realizada no talude continental da regiÃo de Camocim, a 80 km do continente. Seu objetivo principal foi caracterizar o testemunho SIS-134, coletado a uma profundidade de 1350 m, quanto a textura, cor, composiÃÃo quÃmica e mineralogia, na busca de auxiliar na classificaÃÃo dos sedimentos das zonas submersas. Os estudos foram baseados em referencial bibliogrÃfico e utilizadas metodologias de anÃlise geoquÃmica e caracterizaÃÃo dos argilominerais por tÃcnicas de DRX e fluorescÃncia de raios-X. A geologia do talude continental faz parte da margem passiva, tendo sua evoluÃÃo ocorrida no perÃodo de rifteamento da bacia oceÃnica, sendo modelado pela atuaÃÃo do tectonismo, das variaÃÃes do nÃvel mÃdio do mar, da deposiÃÃo fluvial, das marÃ, correntes oceÃnicas, ondas, entre outros. Houve predominÃncia de sedimentos lamosos em todas as seÃÃes analisadas, com teores variando de 75,3% a 90,8%, sendo o menor valor encontrado na base do testemunho, indicando que a Ãrea compÃe um ambiente de baixa energia onde se depositam somente os sedimentos de granulometria mais fina. Os argilominerais encontrados correspondem aos grupos da esmectita, caulinita e ilita. Os valores de ilita foram de 42,36% no topo, 51,32% no meio e 60,9% na base do testemunho, o que pode indicar que no passado houve uma maior influÃncia da aÃÃo fluvial na sedimentaÃÃo deste ambiente. A esmectita obteve nas seÃÃes topo, meio e base, teores de 12,06%, 1,09% e 4,9% respectivamente. A caulinita se apresentou no testemunho com teores de 45,58%, 47,59% e 34,2% respectivos a topo, meio e base. Na composiÃÃo quÃmica do testemunho, foi verificada a predominÃncia de CaO3, seguido de SiO3, Al2O3, e Fe2O3, que reforÃa a influÃncia da sedimentaÃÃo continental do talude. O teor de CaO3 se apresentou elevado em quase todo o testemunho, sendo os maiores valores encontrados nas seÃÃes topo e meio com 95,2% e os menores valores foram encontrados na base do testemunho com 40,5% e 57,1%. O teor de matÃria orgÃnica variou de 7,03% a 36,21%, que se justifica pela baixa energia e lenta deposiÃÃo do ambiente. Os resultados geraram uma maior base nos estudos sobre o mar profundo e sua dinÃmica / This research was conducted on the continental slope of Camocim region, 80 km from the mainland. Its main objective was to characterize the core SIS-134, collected at a depth of 1350 m, about the texture, color, chemical composition and mineralogy, in search of help to classify the sediments of submerged areas. The studies were based on literature references and used methodologies for geochemical analysis and characterization of clay by XRD and X-ray fluorescence techniques. The geology of the continental slope is part of the passive margin, and its evolution occurred during the rifting of the ocean basin, being modeled by the action of plate tectonics, the variations of the mean sea level, fluvial deposition, the tides, ocean currents, waves, among others. There was a predominance of muddy sediments in all sections analyzed, with levels ranging from 75.3% to 90.8%, the lowest value found in the bottom of the core, indicating that the area comprises a low energy environment where is deposited only sediment of finer grain size. The clay minerals found correspond to groups of smectite, kaolinite and illite. Values were 42.36% illite the top, in the middle 51.32% and 60.9% on the basis of the core, which may indicate that in the past there was a strong influence of a river environment. The smectite in the sections got the top, middle and base levels of 12.06%, 1.09% and 4.9% respectively. The kaolinite is presented in the core at levels of 45.58%, 47.59% and 34.2% respective to the top, middle and base. In the chemical composition of the core, there was a predominance of CaO3, followed by SiO3, Al2O3, Fe2O3, and that reinforces the influence of the continental slope sedimentation. The content CaO3 appeared high in almost all the testimony, and the highest values found in the top and middle sections with 95.2% and the lowest values were found at the base of the core with 40.5% and 57.1%. The organic matter content, which ranged from 7.03% to 36.21% is explained by the slow deposition and low energy environment. The results generated a higher based on studies of the deep sea and its dynamics

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