Teses em Geologia e Geoquímica (Doutorado) - PPGG/IG

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/6341

O Doutorado Acadêmico pertence ao Programa de Pós-Graduação em Geologia e Geoquímica (PPGG) do Instituto de Geociências (IG) da Universidade Federal do Pará (UFPA).

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Acesso aberto (Open Access)
Análise da dinâmica das áreas de manguezal no litoral Norte do Brasil a partir de dados multisensores e hidrossedimentológicos
(Universidade Federal do Pará, 2016-12-16) NASCIMENTO JUNIOR, Wilson da Rocha; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252
The objective of this research is to analyze the dynamics of the mangrove areas in the north coast of Brazil from images of remote orbital sensors and hydrosedimentological data (flow and suspened sediment concentration). We tried to understand the existence of causality between the expansion or retraction of the mangroves with the suspened solid discharge calculated from the data of flow and suspened sediment concentration. The mangroves were mapped, using the object oriented classification technique, in the years 1975, 1996 and 2008 based on data from microwave sensors (RADAM / GEMS, JERS-1, ALOS / PALSAR). The data of fluviometric stations and sediments of the National Water Agency were used to calculate the solid discharge in suspension in the rivers Araguari, Gurupi, Pindaré, Grajaú and Mearim seeking to relate the addition and erosion in the areas of mangrove with the sedimentary load of the rivers that drain On the coast. The flow variations reflect the precipitation in the sub-basins of the analyzed rivers and presented a strong and moderate correlation with the temperature anomalies on the surface of the Pacific Ocean evidencing a relation of the El Niño and La Niña phenomena with the precipitation regimes in the Amazon. The variations of suspended sediment concentration were not related to the fluviometric variation suggesting that the annual mean oscillations are reflections of other phenomena (coverage and land use). The results show that the drainage areas of the sub-basins most impacted by the anthropic action contribute with a higher sediment load to rivers that have a higher concentration of native forest. Native vegetation contributes to containment of soil erosion and exposed soil and pasture areas are more vulnerable to soil erosion. The Gurupi, Pindaré, Grajaú and Mearim Rivers presented solid suspended load higher than or equal to the Araguari River. Analyzing the mangroves in the estuaries we noticed the addition of mangroves along the estuaries of the Gurupi and Mearim rivers (Baia de São Marcos) and the reduction of mangrove areas in the Araguari estuary. The Amazon coastal zone is subject to natural processes of great magnitude, but atrophic activities influence the natural dynamics of the region by implementing unsustainable economic practices.
Acesso aberto (Open Access)
Aproveitamento dos resíduos cauliníticos das indústrias de beneficiamento de caulim da região amazônica como matéria-prima para fabricação de um material de construção (pozolanas)
(Universidade Federal do Pará, 2007-12-18) BARATA, Márcio Santos; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; https://orcid.org/0000-0002-3026-5523
The Capim and Jarí regions are the most important kaolin district in the Amazon region, with the largest Brazilian reserves of high whiteness kaolin for paper coating products. Kaolin is obtained from three companies (IRCC, PPSA and CADAM) which produce annually around 1,000 M ton kaolinite-rich wastes derived mainly from the centrifugation phase of the process. The sludge is disposed on artificial sedimentary lakes covering large areas. Another type of kaolin waste is related to a non-processed iron-rich hard or flint kaolin, that overlays the so-called soft kaolin horizon (the main ore). These wastes exhibit appropriate characteristics for the production of high-reactivity metakaolin because they are extremely fine and composed of mainly by kaolinite. The main purpose of this work is to evaluate the feasibility of using these wastes as raw materials to produce mineral admixtures for OPC concretes. The wastes were firstly characterized for x-rays diffraction, thermal analysis, infrared spectroscopy, x-rays fluorescence and SEM. Three heating temperatures were evaluated: 750ºC, 850ºC and 900ºC, followed by pozzolanic activity tests based on traditional mechanical assays using Portland cement and hydrated lime mortars, and “Chapelle” test. The results showed that the more reactive pozzolans are those produced at temperatures that gave rise to higher LOI. The optimum burning temperature to produce metakaolinite from the hard kaolin was obtained at 750ºC while those from the Rio Jari and Rio Capim wastes were at 850ºC and 900ºC. The main reason is related to differences in the amounts of defects from three different wastes. The flint kaolin and Rio Jari waste are mainly composed by a “high-defect” kaolinite while the kaolinite from Rio Capim waste is a “lowdefect” kaolinite. In concrete test using different pozzolans those with metakaolin from wastes improved the mechanical and durability properties in comparasion to silica fume, a industrially manufactured metakaolin and reference concretes.
Acesso aberto (Open Access)
Muiraquitã e contas do Tapajós no imaginário indígena: uma análise químico-mineralógica dos artefatos dos povos pré-históricos da Amazônia.
(Universidade Federal do Pará, 2011-08-25) MEIRELLES, Anna Cristina Resque; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; 1639498384851302
The muiraquitãs, also known as greenstones, are stone artifacts which are carved meticulously into batrachian shapes. These artifacts constitute one of the most prominent symbols of pre-colonial Amazonian culture. These objects are made from extremely hard rocks or minerals. The term muiraquitã was first discussed by Rodrigues (1875) following his exploration of the region of the Nhamundá River. As jade is unknown in the Amazon basin, the muiraquitãs were traditionally considered to represent vestiges of ancient Asian cultures. In recent years, they have become very rare museum pieces, but there is virtually no information on their origin or significance. Even so, analysis of the texture of the surface of these artifacts has permitted the identification of some of the techniques used in their production, which has contributed to the understanding of the productive process. Morphological studies of 17 pieces deposited in the Gemas (Gemstone) and Encontro (Meeting) museums of the Brazilian city of Belém found that three principal groups could be distinguished on the basis of the carving process, which had four stages: paring, perforation, carving, and polishing. In one piece (510), it was possible to identify the use of a rotary tool with a rare abrasive. The results of the mineralogical and chemical analysis of 22 muiraquitãs indicated that they are constituted of one or more of the following minerals: quartz, tremolite, tremolite-actinolite, variscite-strengite, anorthite, albite, and microcline, which are all common materials in any part of Brazil. The predominance of quartz was confirmed by the chemical composition, basically SiO2. In the collection of the Meeting Museum, however, the most intriguing and widely-discussed mineral of all was discovered – jadeite, the constituent of jadeite jade. This mineral was found in pieces 518, 519, 524, and 525. Its percentages of SiO2 (58.6-67.1%), Al2O3 (20-24.7 %), and Na2O (8.8-15.5%) are equivalent to those of the jadeites of Montagua. The confirmation of the presence of jadeite in these pieces from the Meeting Museum reopens the discussion of the mineralogical origin of the muiraquitãs found in the Amazon. The coloration of these pieces vary in their shades of green, from white to greenish, yellow-green, olive green, and milky hues, to dark green, almost black. The predominant color is light green, with “veins” of slightly darker or lighter coloration. The pieces made from tremolite, quartz, amazonite, and jadeite are very hard (generally 5 or 6, but up to 7), and their measurements are: length (44-64 mm), width (22-57 mm), and thickness (15-19 mm). In addition, the mineralogy of 16 beads and 12 pendants belonging to the Mário Simões technical collection of the Goeldi Museum was analyzed. The results indicate that these pieces were normally made of a single mineral, including tremolite, tremolite-actinolite, calcite, quartz, muscovite, hematite, dolomite, and kaolinite, minerals typical of the composition of rocks, such as schists, gneisses, and granitoids, which are amply distributed in the Amazon basin. A combined analysis of the mineralogical composition of the pieces and the geographic location of the finds permitted the conclusion that the artifacts made of greenstone (tremolite or termolite-actinolite) were more widely-dispersed and possibly also of greater prestige, extending from the lower Amazon basin, in the proximity of the Tapajós and Trombetas rivers, as far as the mouth of the Amazon in Amapá. The pieces made of calcite or quartz+muscovite+microcline were found within a more restricted area, in the present-day municipality of Santarém. The raw material for the majority of the pieces investigated – muiraquitãs, beads or pendants – was Amazonian in origin, being found in the crystalline Archean and Proterozoic terrains located both to the north and south of the Amazon, and outcropping in the riverbeds of its tributaries, except for the specimens carved out of jadeite. It was possible to confirm that the peoples of the lower Amazon basin distinguished between harder, brighter and more transparent rocks, which were used mainly for the production of muiraquitãs, while the beads and pendants were made from greenish rocks used to compensate the rarity of the true greenstones, which are generally more difficult to obtain.

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