SIBI! EM BREVE O RIUFPA ESTARÁ LIBERADO! AGUARDEM!

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).

Navegar

Agora exibindo 1 - 20 de 185

Acesso aberto (Open Access)
Acúmulo e exportação de carbono, nitrogênio, fósforo e metais em canais de maré dos manguezais de Marapanim, Costa Norte Brasileira
(Universidade Federal do Pará, 2020-12-18) MATOS, Christiene Rafaela Lucas de; SILVA, José Francisco Berrêdo Reis da; http://lattes.cnpq.br/1338038101910673; https://orcid.org/0000-0002-8590-2462; COHEN, Marcelo Cancela Lisboa; http://lattes.cnpq.br/8809787145146228
In this study, we assessed the potential of intertidal mudflat sediments along mangrove forest to accumulate and export carbon, nutrients (N and P) and metals (Fe and Mn), in addition to examine the influence of the Amazonian seasonal rainfall patterns on the physicochemical conditions, diagenetic processes and exchange of nutrients and metals along the sediment-water interface (SWI) in intertidal mudflats fringed by pristine mangroves. The study was carried out in the Marapanim River estuarine system (northern Brazil), which is fringed by extensive areas of well-developed mangroves, part of the largest continuous and best preserved mangrove forest in the world, located approximately 200 km from west of the mouth of the Amazon River. The results of this work are presented in two articles. The first deals with the potential of stocks and accumulation of COT, NT and PT in intertidal mudflat sediments, in addition we investigate the potential sources of sedimentary organic matter (OM). The second assesses the influence of seasonal rainfall pattern on physicochemical properties, the diagenetic processes and the diffusive fluxes of nutrients at the SWI in the Marapanim mangrove creeks. During wet season the salinity values decreased as a consequence of the increase in rainfall, with a dilution-mixing zone in the top sediment (<15 cm). In the dilution-mixing zone, Fe (III) and Mn (IV) reduction are the dominant anaerobic respiratory processes in the sediments. The redox zonation of sediments oscillated in response to the rainfall patterns, with the highest concentrations of Fe2+ and Mn2+ in deeper sediment layers during the dry season. Under suboxic conditions, the mudflat sediments act as a source of Fe2+, Mn2+, NH4 +, and PO4 3- to the water column, and these fluxes were driven by rainfall. The results indicated that mangrove-fringed mudflats are quite effective in retaining carbon, nutrients and iron in sediment solid phases than exporting to the coastal waters, while can potentially be a significant contributor to the oceanic Mn cycle. The potential of these mangrove creeks to accumulate these elements is directly related to grain size, sources and susceptibility of OM degradation. In addition, temporal variability in pyrite formation revealed that the solid phase retention mechanisms are also susceptible to seasonal effects, with lower concentrations of chromium-reducible sulfur (CRS, mainly pyrite fraction) during the dry season. Therefore, we show that these seasonal variabilities implied substantial changes of physicochemical properties and the diagenetic processes, affecting the release of metals and nutrients from the SWI and their accumulation in the sediment.
Acesso aberto (Open Access)
Análise crítica das metodologias gerais de mapeamento geotécnico visando formulação de diretrizes para a cartografia geotécnica no trópico úmido e aplicação na região metropolitana de Belém escala 1:50.000
(Universidade Federal do Pará, 2001-11-09) COSTA, Tony Carlos Dias da; ABREU, Francisco de Assis Matos de; http://lattes.cnpq.br/9626349043103626; GANDOLFI, Nilson; http://lattes.cnpq.br/2605833412394930
This thesis brings within its scope the critical analysis of the main national and international methodologies of geotechnical cartography (IAEG, Australian, French, EESC-USP, IPT, IG-UFRJ and IG-SP), as well as the classification of a set of rules for the elaboration of geotechnical maps and charts in the Brazilian Humid Tropics. It also presents geotechnical mapping at the scale of 1:50 000, of the Metropolitan Region of Belém, in the State of Pará, comprising the municipalities of Belém, Ananindeua and Marituba. The methodology is based on the above-mentioned cartographic (conventions/ rules), and is presented in the form of eleven cartographic items: a documentary map of the Metropolitan Region of Belém, at a scale of 1:50 000; a documentary map of the central area of Belém, at a scale of 1:10 000; a gradient map; a geological map; a map of unconsolidated materials; a soil use map; a map of institutional areas and conservation units; a map of floodplain and mainland areas; a map of zones of permanent protection of water bodies; a chart of the preferential areas for the exploration of natural construction materials; and a chart of the preferential areas for the installation of sanitary landfills.
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)
Análise evolutiva da paisagem da serra Tepequém - Roraima e o impacto da atividade antrópica
(Universidade Federal do Pará, 2008-01-23) BESERRA NETA, Luiza Câmara; BORGES, Maurício da Silva; http://lattes.cnpq.br/1580207189205228; 1580207189205228; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; 1639498384851302
The north area of Roraima State presents great diversity of geomorphologic featuresformed by dissected plateaus, limited by intermountain plain and relief with a plateau morphology that it is individualized in the extensive plain areas, e.g., of the mountain Tepequém. Since 1930s this was a site of intense activity of diamond extraction what printed changes in the landscape. The main objective of this study is to understand the dynamics evolution of the landscape of the mountain Tepequém under diamond extraction activity and the reason of its erosion susceptibility, being natural or anthropic. To reach these objectives, a description of profiles of soils and saprolitic rock, as well as lateritic profiles were accomplished. Samples of soils, altered rocks, laterites and coal were collected. Besides, width, depth, extension and directional alignment of the channels of the gullies measurements were carried out. The collected materials were submitted to the following analyses: grain size, by humid way; minerals identification by X-ray diffraction and SEM techniques; total chemistry analysis (major elements) by ICP-MS and content of organic matter, humidity and density of the soil measurements. Coal samples were submitted to radiocarbon analyses by AMS (Accelerator Mass Spectrometry). Appling the interpretation of optical images (Landsat-5/TM and Cbers-2/CCD) and the cartographic base, maps of structural alignment, relief (altimetry and declivity), drainage and vegetation covering were also elaborated. The mountain Tepequém stand out among the landscape dominated by relief of hills, residual hills and plane-slightly wavy surfaces because of its rectangular-rhombic format and outline of steep scarps elaborated on sedimentary rocks of Paleoproterozoic. The drainage system of the area delineates parallel, angle-rectangular and faults standards. The relief and drainage morphology of the mountain Tepequém and its around area define a subordination to the structural arrangement E-W, NE-SW and NW-SE directions represented by normal and strike-slip faults. In the mountain Tepequém, the geomorphologic compartments are established by 575 to 670 m high plain intra-valleys surfaces bordered by less than 774m high hills and residual hills and edge slopes less than 1100m high. The bush grassy savanna dominates this landscape and recovers the edge scarps and extends along the regional plain. The ciliary forest covers small stains along the Cabo Sobral and Paiva rivers. This scenery was quite modified because of diamond extraction activity. However, with the decline of this activity, the ciliary forest recovers spontaneously, as the optical images of the last 22 years shows (1984, 1995 and 2006). Intra-valleys plains were developed on sandy soils constituted by medium and fine grain size sandy domains, sub-angles to sub-rounded poorly selected, with low cohesion and small quantity of organic matter. These soils are developed on saprolitic derived of sandstones and siltstones. Locally stone lines and colluvial are observed, usually on the saprolitic. Immature laterites are found in the center-north hills of the mountain Tepequém. Quartz, muscovite in sub-milimetric plates and kaolinite partially involving the grains of quartz are predominant in soils constitution, while the lateritic profiles are constituted by gibbsite, goethite and hematite, besides quartz and kaolinite. Laterite and quartz fragments constitute the stone lines. High concentrations of SiO2 confirm the essentially quartz-character of the soils, while the values of Al2O3, K2O, MgO, Fe2O3 and TiO2 are more expressive in the saprolitic zones, confirming the kaolinite, muscovite and hematite domain, derived of claystones and siltstones. The radiocarbon ages in coal obtained for the superficial materials (colluvial and stone lines) show that these materials were formed at least 3.822 years BP. The intermountain plains reveal in its landscape erosive features in the piping formations, dolines and gullies, developed in the lands with sandy to silt materials domain. The channels of gullies are mainly aligned in the directions NE-SW and NW-SE corresponding to the directions of fractures and faults that section the Tepequém Formation. The seemingly stabilized gullies are partially covered by ferns that grow on the side and bottom surfaces of the channel. The evolution of the landscape of the mountain of Tepequém specially the formation of its general internal structure involves the tectonic still in Proterozoic. The inherited morphology reflects in the steep scarps around as well as in the top such a great synclinorium. The evolution of the landscape of the mountain of Tepequém during Cenozoic is marked by formation of small hills, some of these protected by lateritic crusts suggesting registration of a humid and hot paleoclimate in Pleistocene, which can admit the installation of the drainage net. The erosive process of the fluvial courses allies with the high gradient favored the transport of part of the sediments to W-SW direction, contributing in the formation of the intermountain plains. The current scenery is marked by the erosive retaking favored by the sandy non-cohesive nature of the soils, ally to a paleorelief inclined to the valleys and strongly fractured and failed that causes a strong shallow surface stormflow propitiating the piping formations, dolines and then the gullies. Thus, the diamond extraction activity can contribute in the intensification of the gullies but, however, it was not the decisive factor. Therefore, the evolution of the landscape of the mountain Tepequém in Proterozoic and in Cenozoic until the present is due to the interaction of multiple processes involving the tectonic history, the weathering changes and the several erosion cycles, as well as the restricted sedimentation and the small anthropic contribution.
Acesso aberto (Open Access)
Análise integrada dos depósitos de caulim na região do Rio Capim: fácies, estratigrafia, petrografia e isótopos estáveis
(Universidade Federal do Pará, 2006-09-29) SANTOS JÚNIOR, Antonio Emídio de Araújo; ROSSETTI, Dilce de Fátima; http://lattes.cnpq.br/0307721738107549
The kaolin deposits that occur in the Rio Capim area, east of Cametá Sub-Basin, are inserted in the Ipixuna Formation. This unit distinguishs for presenting one of the largest worldwide kaolin concentrations of excellent quality to the cellulose industry. Beyond the economic character, a great volume of academic works focusing these kaolin deposits had led to pedological and geochemical approaches, but without taking into account their sedimentologic aspects, which are important to understand their genesis. Detailed sedimentologic and stratigraphic studies of the Rio Capim kaolin have been increasingly carried out in the last years, which led to the paleoenvironmental interpretations for the Ipixuna Formation, as well as to discuss better the mode of formation of the soft and semi-flint kaolin units that are typical of this unit. These works served to motivate the integration of sedimentologic and stratigraphic data with optical studies combined with hydrogen and oxygen isotope geochemistry in order to discuss the geologic processes involved in the origin and evolution of the soft and semi-flint kaolin units. The sedimentological analysis consisted in a more detailed facies description and stratigraphic analysis of newly open quarries that were not available during previous investigations. The additional exposures led to a better characterization of the lower kaolin unit, known as the “soft kaolin”, which is well stratified, favoring facies analysis. Hence, the soft kaolin unit consists of kaolinitized sandstones and kaolinitized pelites that were formed in tidally influenced fluvial channels (Facies Association A), tidal channel (Facies Association B), tidal flat/mangrove (Facies Association C), and tidal sand bar/tidal sandy flat (Facies Association D). These depositional environments are attributed to a tide-dominated estuarine system. Petrographic studies and scanning electronic microscopy (SEM) of the kaolin deposits in the study area had their composition was strongly modified after sedimentation. The soft kaolin consists of kaolinitized quartz sandstone and either laminated or massive pelites, which are composed by fragments of meta-volcanic lithic and volcanic felsic rocks, as well as metamorphic and granitics rocks. These lithologies were strongly modified during kaolinitization, as revealed by the intense replacement of the framework grains by kaolinite of three types, named herein as Ka, Kb and Kc kaolinites. Ka kaolinite occurs dominantly associated with kaolinitized sandstones, being characterized by pseudohexagonal crystals 10-30 μm in diameter, which are organized as booklets or vermicular forms that reach up to 400 μm in length. Kb kaolinite dominantes in the pelites, and consists of pseudohexagonal crystals 1-3 μm in diameter, occurring as isolated, face-to-face and parallel to pseudo-parallel crystals. Kc kaolinite forms pseudohexagonal to hexagonal crystals of 200 nm in diameter. It occurs dispersed through the soft unit, increasing significantly in abundance in association with paleosols at the top of the unit. The semi-flint kaolin deposits are constituted mainly of reworked grains derived from the underlying soft kaolin unit that are mixed with grains derived from metamorphic and granitic sources. These deposits are dominantly composed of Kc kaolinite that was formed during weathering. The deuterium (δD) and oxygen (δO) isotope analysis of the kaolin deposits from the study area helped to discuss better the evolution of the different types of kaolinites described above. Hence, the soft kaolin deposits display δO values varying between 6.04 ‰ and 19.18 ‰ in the Ka+Kb kaolinites, and between 15.38 ‰ and 24.86 ‰ in the Kc kaolinite. The δD values from this unit vary from – 63.06 ‰ to 79.46 ‰, and from –68.85‰ to -244.35‰ in the Ka+Kb and Kc kaolinites, respectively. The semi-flint kaolin deposits are characterized by δO and δD values ranging from 15.08‰ to 21.77‰, and from -71.31‰ to -87.37‰, respectively. Based on these data and on the isotopic composition of both meteoric and ground waters, it was possible to conclude that the kaolinites had not been formed in balance with modern weathering. These values represent the isotopic composition during the time of formation of the kaolinites, as well as mineralogical contamination of framework grains that are now replaced by kaolinites.
Acesso aberto (Open Access)
Aplicação da composição isotópica de multielementos no monitoramento ambiental de área circunvizinha à barragem de rejeito: o caso da mina de cobre da Serra do Sossego, Canaã dos Carajás – PA
(Universidade Federal do Pará, 2017-06-09) OLIVEIRA, Simone Pereira de; MOURA, Candido Augusto Veloso; http://lattes.cnpq.br/1035254156384979
Tailings dams from ore mining activities are relevant compartment for environmental monitoring because the dam can present undesirable forms of water outlets such as infiltration. The present thesis proposed multielement isotope study in order to evaluate the use of the isotopic composition of oxygen, hydrogen, strontium and lead as a tool for the environmental monitoring of groundwater vulnerable to the tailings dam. This research was conducted in the area of the Serra of Sossego copper mine and, in addition to the isotope study, the hydrochemical characterization of groundwater and surface water was caried out. Besides, the direct reading of the isotopic composition of lead (without chemical treatment of the water sample) was applied for the first time, using multicollector inductively coupled plasma mass spectrometry, in the laboratory Para-Iso. The hydrochemical characterization of groundwater in the Serra do Sossego mine area showed that it is moderately acid (pH ~ 6). Only the AP15 and PS32 wells, under the influence of the drainage of the mixed pile (ore waste + sterile), presented high electrical conductivity (599 μS / cm2 and 694 μS / cm2) and the higher sulfate content (1.82 to 6.57 Meq/L). In general, iron (29.7 mg/L), manganese (69.7 mg/L) and copper (24.9 mg/L) present the highest metal content in the groundwter. In terms of the isotope studies, the groundwater of PS17, PS04, AP15 and PS32 wells and the water of the Dam present the least radiogenic lead isotopic composition. The water sampled in the AP15 and PS32 wells would be representative of the lead isotope signature of groundwater in the mine area (206Pb/207Pb = 1.1481 to 1.1663) and, probably, is indicative of the lead isotope composition of the meteroric water. The lead isotope composition of the groundwater of the wells PS04 (206Pb/207Pb = 1.1784-1.1850) and PS17 (206Pb/207Pb = 1.2100 to 1.2160) may indicate a small contribution of the rocks of the region (206Pb/207Pb > 1.6807). In turn, the lead isotope signature of water of the Dam (206Pb/207Pb = 1.2279) suggests, as expected, a slightly more pronounced contribution of the ore and the rocks. On the other hand, the lead isotopes of the water sampled in the wells MNA23 and PS06 show a more radiogenic signature (206Pb/207Pb = 1.6741 to 1.9196), which is similar to those of the chalcopyrite and the diabase of the Sequeirinho open pit, revealing a more significant contribution of the ore and rocks. As the lead isotope composition of water from the dam is different from that of the groundwater, it can be used for the environmental monitoring of the influence of the water from the dam in groundwater in the Serra of Sossego mine area. In those wells with less radiogenic lead isotope signature, a possible contribution of the water from the dam would result in a more radiogenic lead isotope composition in the groundwater. Conversely, in those wells with more radiogenic lead isotope signature, a contribution of the water dam for the groundwater would decrease the values of the measured lead isotope ratios. On the other hand, the application of the sulfur isotopes for environmental monitoring presented some limitation in the study area, due to the lack of contrast of the sulfur isotope composition among the sulfides of the Sossego deposit (δ 34S ~ 2-7 ‰), the water from the dam (δ 34S ~ 2 ‰), and the drainage of the mixed pile (δ 34S ~ 2‰). This prevents the recognition of a possible contribution of the tailings dam to groundwater. Mixing models using the 87Sr/86Sr ratio as a function of the strontium concentration and δ 18O values, also showed some limitations, since there is no contrast between the values of the 87Sr/86Sr ratio of the water from the dam (0. 7458 to 0.7539) and the rocks of the mine area (granite ~ 0.7474). Such similarity, in principle, would not allow identifying the contribution of the water from the dam. However, since groundwater generally exhibits less radiogenic values of the 87Sr/86Sr ratio (0.7161 to 0.7283) and well below the dam values, the strontium isotopic composition can be used for environmental monitoring of groundwater. Hydrogen and oxygen isotope data revealed that, in the rainy season, the groundwater presented values of δ 18O and δ D varying from -2.74 to -7.17‰ and from -15.6 to -46.0‰, respectively. In turn, an enrichment of 18O and D, with values of δ 18O between -1.67 and -7.29 ‰ and of δ D between -0.23 and -46.1 ‰, is observed in the dry season. Hydrogen and oxygen isotope composition of the water from the dam (δ 18O from 1.24 to 2.79 ‰ and δ D from 1.40 to 7.0 ‰) is very different from those of the groundwater and of the drainage of the pile. A mixing model performed with oxygen and hydrogen isotopes showed that these elements are the ones that best respond as indicators of the contribution of the waters from the dam to groundwater. The application of this model revealed no influence of the water from the dam on the groundwater during the period of this study. The results obtained in this multielement isotopic study suggest that the environmental monitoring of the groundwater of the Serra do Sossego mine to investigate the possible contribution of the water from the dam, can be done more efficiently with the oxygen and hydrogen isotopes. The isotopic compositions of lead and strontium can also be used for monitoring the groundwater, but this has to be done more systematically due to the small contrast between the isotopic composition of these elements in the dam water and in the groundwater. Finally, the isotopic composition of sulfur is the one that would contribute least to the environmental monitoring of the groundwater of the study area.
Acesso aberto (Open Access)
A aplicação da cromatografia gasosa acoplada (GC-FID), isótopos estáveis, palinologia e razão C:N na reconstituição paleoambiental de manguezais do Estado da Bahia e Espírito Santo.
(Universidade Federal do Pará, 2024-07-30) SILVA, Fernando Augusto Borges da; ALBERGARIA-BARBOSA, Ana Cecília Rizzatti de; http://lattes.cnpq.br/2666263256585897; FRANÇA, Marlon Carlos; http://lattes.cnpq.br/8225311897488790; https://orcid.org/0000-0002-3784-7702
Mangroves depend on ideal geomorphological, geochemical, and climatic factors to develop. Brazil, with its highly indented coastline under tropical and sub-tropical climate regimes, presents suitable conditions for the establishment of these ecosystems and distribution. The dynamics of these mangroves can be influenced by factors related to climatic variations and changes in hydrodynamic flow, resulting in modifications in sediment input and the origin of organic matter. These changes can be observed throughout the Holocene in different regions in of the country. On the northeast and southeast coast, the evolution of these ecosystems is associated with fluctuations in relative sea level (RSL) and sedimentary dynamics, while in the southern region, the change in the distribution of mangroves is a reflection of fluctuations in the RSL and climate changes caused by warming global. Recent studies seek to describe the evolution of these environments based on the elemental and isotopic characterization of organic matter. These constitute important tools in paleoenvironmental reconstruction. However, it is necessary to remember that the comparative analysis of the largest possible number of independent parameters is relevant as it adds value to the research and increases the reliability of the data to be analyzed, generating more precise information. Therefore, aiming to unravel the dynamics of organic matter in mangrove environments, as well as understanding movements of expansion and/or contraction of these ecosystems, analyzes of nalkanes were carried out using chromatography (GC-FID), associated with the sedimentary study, pollen data, isotopic and elemental analyses, synchronized with 14C and 210Pb dating, which allowed obtaining information about past biogeochemical processes and environmental changes during the Holocene and Anthropocene in the coastal plain at the mouth of the Itapicuru river (BA) and at the mouth of the Barra Seca and Jucu rivers (ES). Thus, the results of this research are presented in five scientific articles. The first, see chapter III, deals with the expansion of mangroves at the mouth of the Itapecuru river (BA) during the Anthropocene. The second scientific article (chapter IV) deals with the dynamics of mangroves at the mouth of the Barra Seca River, on the northern littoral of the State of Espírito Santo. The third article (chapter V) discusses the palynology tool used to understand the dynamics of coastal vegetation.The fourth article (chapter VI) presents the environmental changes that occurred at the mouth of the Jucu River, on the central coast of the State of Espírito Santo. Finally, the fifth article presents the results of n-alkanes analyses, compared with isotopic, elemental, palynological data, and 14C dating on the coastal plain of the Barra Seca River.
Acesso aberto (Open Access)
Aplicação de resíduos da mineração de bauxita na síntese de geopolímeros
(Universidade Federal do Pará, 2022-04-08) BARRETO, Igor Alexandre Rocha; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
The process of extraction and beneficiation of bauxite deposits in the bauxite province of Paragominas/Rondon do Pará can generate large amounts of waste, mainly in two stages of the process: mining and processing. In the mining stage of the deposits, the “residue” comes from the removal of a thick layer of clay material (known as Belterra Clay). On the other hand, the “residue” from the beneficiation process is generated after the crushing, grinding and washing stages, which give rise to a large amount of clay material dispersed in a large amount of water. For the present study, it selected Belterra clay from the bauxite deposits of Rondon do Pará, a sample of Bauxite Washing Clay from the Hydro company and a sample of kaolin benefited from Imerys Company. The samples and geopolymers were characterized by X-ray Diffraction (XRD), X-ray Fluorescence (FRX), Gravimetric Thermal Analysis (TG), Differential Exploratory Calorimeter (DSC), Optical Emission Spectrometry with Coupled Plasma (ICP-OES) and Laser Particle Analyzer (APL). Geopolymers were synthesized from Belterra clay, microsilica and NaOH according to the Box-Benkhen design. Synthesis of geopolymers from Belterra clay and beneficiated kaolin was also carried out (a comparative study) using KOH and microsilica. Finally, geopolymers were synthesized from Bauxite washing clay with NaOH and microsilica according to the Doehlert design. In the study with only Belterra clay, the highest resistance result was 47.78MPa and the lowest result was 7.05MPa. In the comparative study between Belterra Clay and beneficiated kaolin, the best results of compressive strength were obtained with the beneficiated kaolin. The compressive strength results of the geopolymers synthesized from the Washing Clay ranged from 8.99 to 41.89MPa. These results demonstrate the positive potential of both samples for the synthesis of geopolymers that can be used as possible “Eco-friendly” substitutes for traditional materials, mainly ceramics and cement.
Acesso aberto (Open Access)
Aproveitamento do rejeito de caulim na produção de alumina para cerâmica e sílica de baixa granulometria
(Universidade Federal do Pará, 2000-11-29) FLORES, Silvia Maria Pereira; NEVES, Roberto de Freitas; http://lattes.cnpq.br/9559386620588673
The Amazon region detains 10% of the world reserves of kaolim. Since the seventy's, two great amazonic beds of kaolim are explored, producing kaolim for paper cover. In the beneficiation process, it's generated an elevated volume of polluted industrial residue which is deposited in extensivas and onerous lagoons of sedimentation. Because of the residue is very voluminous, these lagoons become an environmental problem of great proportions, due the extensivas deforested areas used for their constructions ( Barata, 1998). In this work, are suggested altematives of economic utilization of this residue, which is constituted, mainly, by a suspension of the claymineral kaolinite, for the production of pozolane, aluminium sulphate, the synthesis of the ammonium alum and alumina for ceramics utilization. The methodology constitutes in the drying and the calcination of the residue, followed by the extraction of the AI retained by the acid lixiviation H2SO4 ) followed by the ammonium alum crystallisation, for the reaction with the concentrated NH4OH, by means of pH control, and later calcination at 1200°C, getting a-Al2O3, with no sodium and Iow granulometry. From the aluminas obtained, are made bodies of proof smashed and sintered at 1600°C, to the determination of the ceramics properties, which are compared to one of the commercial alumina. After the acid lixiviation for the AI extraction, results as an insoluble material, an amorphous silica, for which it is suggested, as an additional contribution, an economic application, using it as artificial pozolane in building portland cement, making mechanics tests for the evaluation of its performance. The material that were used and synthesized were characterized throught the use of the X ray diffraction, eletronic scanning microscopy, the infra-red spectroscopy, thermogravimetry, differential thermic analisys, particle size analysis, specific area BET, porosity, chemical analisys throught umid means and throught X ray fluorescence.
Desconhecido
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.
Desconhecido
Arcabouço estrutural e geocronologia dos granitóides da região de Várzea Alegre: implicações para a evolução crustal da Província Borborema
(Universidade Federal do Pará, 2024-07-25) SOUSA, Luis Kennedy Andrade de; DOMINGOS, Fabio Henrique Garcia; http://lattes.cnpq.br/3975188208099791; https://orcid.org/0000-0002-2447-3465; GALARZA TORO, Marco Antonio; http://lattes.cnpq.br/8979250766799749; https://orcid.org/0000-0002-7271-4737
In the Borborema Province, in northeastern Brazil, several granitic batholiths and plutons are found, which are records of subduction and collision episodes related to the Brasiliano Orogeny. Within this large orogenic system, the emplacement mechanisms of many granites are closely related to the development of deep-seated shear zones, one of which is the Patos Shear Zone, which in its western segment is composed of slices of rocks such as granites, gneisses, metapelites, quartzites, and amphibolites that form an imbricated system. In this context, the present work was carried out with the aim of bringing new geochronological and microstructural data to add to the understanding of the nature of the processes that formed and modified the undifferentiated granitoids in the Várzea Alegre region (CE). The granites are classified as Biotite Monzogranite and Garnet Monzogranite, they present phaneritic and porphyritic textures, in some places, their mineralogical composition is mainly composed of plagioclase, K-feldspar, and quartz, in addition to biotite, muscovite, and garnet. The granitoids are composed of elongated bodies concordant with the host rocks. The deformation imposed on the granitic bodies developed ductile structures with NE-SW orientation and kinematic criteria indicate that the deformation occurred predominantly dextral. Microstructural features, observed mainly in rocks near the edges of the granitic bodies, show that quartz crystals exhibit microstructures such as sutured to lobate contacts, undulating extinction, ribbons, and the chessboard pattern, indicative of recrystallization by grain boundary migration (GBM), compatible with temperatures of 500ºC. Biotite crystals that define the mylonitic foliation characterize a spaced foliation that separates microlite domains formed by aggregates of quartz and plagioclase, with asymmetric lenticular geometry in the granites, similar to the foliation impressed on the gneisses of the Granjeiro Complex. Based on EBSD data, the granites exhibit a grain size distribution with a concentration of crystals <100 μm. From the pole figures, the quartz OPC shows that the dominant system was rhombohedral to prismatic, indicating a medium to high deformation temperature, in a context of progressive non-coaxial deformation. However, from the interpretation of the misorientation angle, it is shown that during the deformation history of the granites, these bodies underwent lower temperature deformation. U-Pb geochronological data on zircon provided crystallization ages of 573 to 576 Ma for this granitic magmatism. The Hf-TDM C model ages of these granitoids ranged from 2.84 to 3.30 Ga and the ƐHf(t) values from -21.9 to -29.6 suggesting a strong incorporation of mesoarchean crustal source. Similar Sm-Nd data in whole rock show that these granitoids have Nd-TDM model ages between 2.14 and 3.33 Ga and ƐNd(t) values between -20.02 and -31.79, suggesting a strong contribution from meso paleoarchean and paleoproterozoic crust (orosirian to riacian) to the formation of the granitic magma that originated the granites in the Várzea Alegre region (CE). These granitic bodies are classified as Itaporanga type and sin-transcurrent, as they have similar ages and structural features to other sin-transcurrent granitic bodies in the Borborema Province. These granites were generated from magmatism associated with the change in the predominant deformation in the Borborema Province, which was the result of the final stages of the Brasiliano Orogeny within the context of simple deformation, with the development of large shear zones.
Desconhecido
Arenito zeolítico com propriedades pozolânicas adicionadas ao cimento Portland
(Universidade Federal do Pará, 2011-08-29) PICANÇO, Marcelo de Souza; BARATA, Márcio Santos; http://lattes.cnpq.br/7450171369766897; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
The proper use of pozzolans enables the production of special cements with lower manufacturing cost and higher durability in comparison with cements without mineral additions. It also enables significant gains in productivity and extending equipments life in the fabric, limestone reserves, and also helping in the reduction of CO2 release into the atmosphere. Zeolites have been used as pozzolanic material in mixtures with Fuller’s Earth and water in buildings from the ancient Roman Empire. Nowadays, there are many discussions involving pozzolanic reactivity of natural zeolites in the incorporation of Portland cement. In the Northeastern region of Brazil, sedimentary zeolites related to sandstones of the Parnaiba Basin wer discovered by the Geological Survey of Brazil in the 2000s. These sandstones are mainly composed by quartz, natural zeolites (estilbity) and clay (smectite). Preliminary studies have pointed that this sandstone may be used as pozzolanic material in Portland cements. The material must be previously sieved to remove quartz and thermally activated, since stilbite is a zeolite with low pozzolanic activity. The main objective of this work is to advance the understanding of the factors that govern the quality and performance of Portland cement modified with this zeolitic sandstone. For this work the structure was divided into three main stages, related to three specific objectives, so that the results are presented in the form of three scientific papers, described as follow: - Evaluation of the natural pozzolanic activity of the zeolitic sandstone to be used as mineral addition in the Portland cement. - The determination of which particle size provides the highest zeolite and smectite concentration, besides the calcination temperature that leads to a higer pozzolanic activity. - The establishing of the best amount of thermally activated zeolitic sandstone to be incorporated as a mineral addition in the Portland cement. During all phases, different instrumental techniques were used for the chemical and mineralogical characterization of the starting materials and products (sandstone + lime mortar, mortar with Portland cement + sandstone + Portland cement pastes sandstone), including: spectroscopy x-ray fluorescence, x-ray diffraction, thermal analysis and scanning electron microscopy. Heat-flow calorimetru assays were carried out to evaluate the physical properties, besides mechanical testing of compressive strength of cement mortars Porltand. In the first stage of the experimental program, the zeolitic sandstone was sieved into different granulometric fractions in order to remove the inert phases (quartz and other minerals), and concentrate the zeolite for further pozzolanic assays. In the second stage, after the first characterization of the samples, we used the zeolitic sandstone that passed in the # 200 and # 325 sieves and calcined at temperatures of 150º C, 300° C and 500° C. Finally, in the third stage, # 200 fraction was calcined at 500 ° C and mixed in different proportions (10, 20 and 30%) in the mortar. The results of the first stage, which culminated in the first article showed that the zeolitic sandstone accelerated the hydration of Portland cement due to the extreme fineness of the material. The sandstone showed pozzolanic activity, and estilbite is the main responsible for this behavior. However, the reactivity was slightly lower than the minimum required to be employed as pozzolan on an industrial scale. Additional studies are needed to ascertain if the thermal treatment between 400° C and 300o C could increase the pozzolanic activity of the sandstone due to the destruction of the crystalline structure of both estilbite and smectite. For the second stage, the results showed that the # 200 fraction was the most suitable because of the higher estilbite concentration (15%) in comparison to the # 325 ssample (2%). The calcination temperature of 500º C has provided the highest pozzolanic activity due to more effective destruction of the crystalline structure of both estilbite and smectite. More moderate temperatures of 150° C and 300° C were not enough. Mortars with the 200 # sample calcined at 500 ° C reached values smaller as those required for a material to be considered as a pozzolane, in this case, 6 MPa for mortar of lime and 75% for the pozzolanic activity index (IAP). The results showed from the third stage showed that the AZ2-3 mixture (10% of zeolitic sandstone incorporated in Portland cement type CPI-S), showed the best result of compressive strength and mineralogical properties of the samples suitable for the production a commercial cement type CPII-Z. In general, one concludes that the zeolitic sandstone from northeastern Brazil has the potential feasibility of producing a CPII-Z cement, whose pozolan contents ranges from 6 to 14% in the Portland cement, according to the ABNT - NBR 11578. Although the strength of the mortar with 10% of AZ2- 3 has reached resistance values close to the reference mortar with 100% of CPI-S, further studies should be carried out in order to find better proportion of sandstone and to meet the requirements for future commercialization.
Acesso aberto (Open Access)
Argamassas históricas de Belém do Pará.
(Universidade Federal do Pará, 2019-09-16) LOUREIRO, Alexandre Máximo Silva; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
The city of Belém, northern Brazil, known as the metropolis of the Amazon, was established on the banks of the Guajará Bay on January 12, 1616, with the denomination of Nossa Senhora de Belém do Grão-Pará, capital of the Grão-Pará province, now the state of Pará. Currently, Belém still has layers of lime mortar on its colonial and imperial buildings, which protect the secular structures and provide evidence of how this material was produced early in its history. Over the years, the deteriorating aspects identified in lime mortars, which damage both aesthetics and functionality, are related to the humidity, saline efflorescence, biological colonization, and/or anthropic actions. Once deteriorated, mortars require maintenance, consolidation, or replacement, which are difficult procedures that can lead to the use of inappropriate materials. Therefore, a good collect and characterization strategies of the original material is necessary for the restoration of historical monuments, because in studies focused on restoration science, the intervention strategy needs to include the use of building materials compatible with the original materials. Thus, the main objective of this doctoral thesis is to determine the characteristics and properties of historical mortars in Belém do Pará from the 18th and 19th centuries, as well as to propose a restoration mortars compatible with the historic mortars, which using industrial waste from Amazon Region. Therefore, this thesis was structured in three independent and complementary thematic articles, which addresses the topic of the historical mortars of Belém do Pará, since their characterization until the proposal of restoration mortars: 1) Investigation of the historical mortar of Belém do Pará, Northern Brazil; 2) How to estimate the binder: aggregate ratio from aerial lime-based historical mortars for restoration? and; 3) The use of industrial waste of the Amazon region in lime-metakaolin restoration mortars: compatibility assessment. Thus, the physical, chemical and mineralogical characteristics were determined, as well as the physical and mechanical properties of the historical material and the restoration material. The results of the historical mortars characterization pointing their main components, their functions and raw materials, besides indicating the analytical techniques used for binder: aggregate ratio quantification, which obtained good accuracy and reliability in your results. Moreover, the results show a wide range of characteristics and properties obtained through restoration mortars, which can serve as a benchmark for other studies or even for practical applications in historic masonry. Therefore, it was possible to identify the restoration mortars most compatible with the historical mortars of Belém do Pará, Northern Brazil.
Acesso aberto (Open Access)
Aspecto tectôno-sedimentares do fanerozóico do nordeste do estado do Pará e noroeste do Maranhão, Brasil
(Universidade Federal do Pará, 1992-09-16) IGREJA, Hailton Luiz Siqueira da; FARIA JUNIOR, Luis Ercílio do Carmo; http://lattes.cnpq.br/2860327600518536
A synthesis of the tectono-sedimentary evolution of the Phanerozoic at Northeastern Pará and Northwestern Maranhão is discussed with enphasis to the Bragança-Viseu and São Luis basins. This research is based on field observations, gravity (Bouguer Anomalies), magnetic, seismic, and borehole data interpretations. Five sedimentary sequences are defined: 1) Piriá-Camiranga (Cambrian-Ordovician to Silurian), 2) Lower Itapecuru (Lower Cretaceous), 3) Upper Itapecuru (Upper Cretaceous), 4) Pirabas-Barreiras (Oligocene-Mioceneto Pliocene) and 5) Pará (Quaternarg). The regional basement is an igneous-metamorphic assemblage which outcrops in two windows. The sedimentary and structural features of the Piriá-Camiranga sequence are consistent with a tectono-sedimentary model of coastal environment with fluvio-glacial influence related to a tilted blocks system induced by strike-slip motion. This sequence represents an evolutive stage coincident to the Eo-Hercynian paroxysm (Paleozoic) which ended with the closure of the Atlantic I (first geotectonic cycle of the Gondwana). The Lower and Upper Itapecuru, as well as the Pirabas-Barreiras and Pará sequences, are related to the Equatorial Atlantic opening during the Mesozoic and Cenozoic times. They are analysed by severa), authors which reached the interpretations refered to as Models of: Fracture Zones; Anti-clockwise rotation of Africa; Intumescence and fracturing; Clockwise rotation of the South America Nate; and Wrench Tectonics. These models were experimented for the studied area. The time and environments of the sedimentary processes are related to the rift and pos-rift phases of the equatorial coastal basins, but these models were not adequate to explain the structural features. A new model is proposed to explain the origin and development of the basins taking into account a regional NE-SW extension axis and formation of the Bragança-Viseu and São Luís basins with similar polarities. The tectono-sedimentary map for the Phanerozoic of the Northeastern Pará / Northwestern Maranhão enhances the compatibility of the depositional and tectonics systems with two periods of oceanic opening of the Northern Gondwana border.
Acesso aberto (Open Access)
Aspectos lito-estruturais e evolução crustal da região centro-oeste de Goiás
(Universidade Federal do Pará, 1985-11-13) COSTA, João Batista Sena; VILLAS, Raimundo Netuno Nobre; http://lattes.cnpq.br/1406458719432983; HASUI, Yociteru; http://lattes.cnpq.br/3392176511494801
The study area is bounded by the cities Paraíso do Norte, Gurupi, and Dianópolis in north-central Goiás State. The area contains diverse lithostratigraphic units and various generations of structures related to distinct thermo-tectonic events. Based on the distribution and the petrographic and structural characteristics of the ancient rock assemblage, four litho-structural domains were defined and attributed to the Archean. Domain "1" includes the region of Almas-Dianópolis and is interpreted as part of granite-greenstone terrane. It includes a group of tonalitic gneisses with associated supracrustal rocks (Goiano Complex), a sequence of metavolcanic rocks and metasediments (Riachão do Ouro Group), and various tonalite bodies (Serra do Boqueirão Suite) intruded into the earlier units. The evolution of the domain includes three principal deformational events: a) Formation of the amphibolites and/or biotite gneisses and granitoids characterized by sub-vertical banding oriented N10ºE and accompanied by mineralogical changes under conditions of amphibolite facies; b) deposition of the Riachão do Ouro Group, followed by isoclinal folding oriented N10°E and consequent transformation to greenschist facies. The emplacement of the tonalitic diapirs of the Serra do Boqueirão Suite is related to this event; c) a foliation gently inclined to the SE resulting from a simple low-angle ductile-brittle shearing process which affected the west part of this domain, transforming the rocks of the Goiano Complex into mylonitic gneisses under amphibolite facies conditions. Domain 2 includes the counties of Porto Nacional, Brejinho de Nazaré, and Natividade in the east-central part of the area. It is characterized by granulitic gneisses (Porto Nacional Complex), by tonalitic gneisses with associated supracrustal rocks (Manoel Alves Complex), including metasediments and metavolcanics (Morro do Aquiles Formation), and by pegmatitic granites such as the Xobó Suite. The different lithologic units take the form of lenses or sub-horizontal concordant to sub-concordant bodies with strike N30°E. They show structural features produced by a low-angle ductile-brittle shearing process under amphibolite facies conditions. Superposed on the low-angle features are various zones of high-angle directional shear having different intensities of deformation, but all in greenschist facies conditions. Domain 3 is within the NW part of Paraiso do Norte county and is interpreted as a granite-greenstone terrane similar to that of Domain 1. This Domain includes the Colméia Complex, the Rio do Coco Group, and the alkaline gneisses of Monte Santo. Two principal deformational phases are responsible for the structures in this domain: a) folding (S) of the gneissic granitoids of the Colméia Complex into recumbent folds oriented E-W. The axial plane schistosity (S1) formed in medium to amphibolite facies conditions; b) deposition of the Rio do Coco Group, discordant with the Colméia Complex, followed by sub-vertical folding oriented E-W. The second generation of folds in the Colméia Complex is related to this deformational event. Domain 4, in the west-central part of the area, includes parts of Paraíso do Norte, Fatima, Gurupi, and Porto Nacional counties. This domain is composed of the Rio dos Mangues Complex, the Matança and Serrote Suites, and the alcaline gneisses of the Serra da Estrela, distributed in sub-concordant sheets oriented N30°E. Similarly to that observed in Domain 2, these rock assemblages show structural features related to low-and high-angle shearing events. The transition between Domains 1 and 2 and between Domains 3 and 4 is gradational, such that two ancient blocks of crust are defined (Domains 1+2 and 3+4] separated by a belt of granulitic rocks (Porto Nacional Complex). The zone of juxtaposition corresponda to a belt of low-angle ductile shearing developed by the overthrusting of the Brazilian block, on the east, onto the Araguacema block to the west. Similar geologic conditions have been well characterized in South Africa, in western Greenland, and in NW Scotland and are beginning to be described in various regions in Brazil, constituting a new way to understand the relations between Archean terranes. Granite bodies of the Lajeado Suite at the end of the Lower Proterozoic and ultrabasic bodies in the first half of the Middle Proterozoic were injected into this crustal segment stabilized at the end of the Archean. During this epoch the Transbrazilian Lineament became defined as a brittle shear zone. Basins were developed in the second half of the Middle Proterozoic, with deposition of the Baixo Araguaia Supergroup and the Natividade Group. These two are separated today by a block limited by the cities of Paraíso do Norte, Gurupi, and Porto Nacional. The Transbrazilian Lineament was reactivated in this period.At the end of the Middle Proterozoic an E-W regional compression produced the Araguaia and Uruaçu fold belts. The evolution of the Araguaia fold belt involved four stages of structural deformation. In the first stage, N-S recumbent folds were formed having axial plane schistosity (S1) developed in intermediate amphibolite facies to intermediate greenschist facies conditions. The intermediary stages involved folding and refolding of the S1. The last stage is related to the formation of domai structures resulting from the intrusion of the granite bodies of the Santa Luzia Suite. As a result of this evolution, the Araguaia belt has an importent asymmetry characterized by intensification of deformation and mineralogical transformations from west to east. The Uruaçu fold belt is In general characterized by folds with variably-oriented axial planes and mineralogical changes tipical of greenschist facies. In the studied region, regular variations In deformational intensity and metamorphic degree were not found. The immature sediments of the Monte do Carmo Formation are the products of the last lithogenetic processes of the Middle Proterozoic in the area. During the evolution of the Araguaia and Uruaçu fold belts, the north part of the Goiano massif had a limited participation in such a way that it functioned as a rigid block with respect to the folding on either side. The final products related to the polycyclic evolution of this crustal segment during the Priecambrian are represented by directional fault systems oriented principally N40º -60ºE and N40º -50º W. The NE system of faults reflects a reactivation of the Transbrazilian Lineament in the Upper Proterozoic. Thick sedimentary sequences were deposited in the Phanerozoic and new movements on the Transbrazilian Lineament caused the development of important block faulting which is reflected in part by the present-day geomorphology of the area.
Acesso aberto (Open Access)
Aspectos litoestruturais e mineralizações Salobo 3A (Serra dos Carajás-PA)
(Universidade Federal do Pará, 1996-10-29) SIQUEIRA, José Batista; COSTA, João Batista Sena; http://lattes.cnpq.br/0141806217745286
The Salobo district is located at the Carajás Province in the Cinzento strike-slip system, and is formed of supracrustal rocks of the Salobo Group and gneisses of Xingu Complex, which were assembled by several generations of shear zones. The Salobo Group includes magnetite-fayalite schist, biotite-almandine-magnetite-fayalite-grϋnerite schist, biotite schist, anfibol schist, chlorite schist, banded iron formation and quartzite. The Xingu Complex includes banded tonalitic gneisses, trondhjemitc and granodiritic gneisses, partialy migmatized. The older shear zones correspond to ductile thrusts to which the generalized imbrication of the lithological units and the tectonic layering, defined by strips and lenses of supracrustais rocks alternated with gneisse is due. Their movements is synchronous to that of the Itacaiúnas belt; minerals transformations under thermal conditions of amphibolite facies, as well as important modifications in the stratigraphic relationships of several lithological units, are related to therm. The second generation of shear zones formed the transtensive Salobo-Mirim duplex. They are sinistral strike-slip shear zones, linked by normal shear zones along which minerals transformations of greenschist facies occurred. The development of the duplex was controled by the former tectonic layering, and its assymetric shape was influenced mainly by the presence of a basement gneiss megalense. The third generation of shear zones is of transcurrent type, with NW-SE and NNW-SSE trends, which modified the Salobo-Mirim duplex geometry, and are interpreted as X features linked to the sinistral moviments. The shear zones of the west corner of the area represent the propagation of a horse tail structure at the west end of the Carajás fault; in these case, they could be oblique thrust. The Salobo 3A deposit is situated in the central part of a normal oblique shear zone, which belongs to a release bend along the main strike-slip shear zone of the Salobo-Mirim duplex. The copper and gold mineralizations are hosted in extension structures, as single and composite pull-apart structures, transtensive sigmoide stringers, tension gashes, pressure shadows and star strucutures in the cross-cutting zones of descontinuities. The Salobo 3 A deposit is an example of concentracion/reconcentracion of cooper and gold mineralizations in s transtensive shear zone due to deformational, hydrothermal and metamorphic processes.
Acesso aberto (Open Access)
A associação anortosito-mangerito-granito rapakivi (AMG) do Cinturão Guiana Central, Roraima, e suas encaixantes paleoproterozóicas: evolução estrutural, geocronologia e petrologia
(Universidade Federal do Pará, 2002-12-19) FRAGA, Lêda Maria; COSTA, João Batista Sena; http://lattes.cnpq.br/0141806217745286
The geological mapping on a scale of 1:250,000, of an area of approximately 22,500 km2 in the central region of the state of Roraima, combined with the petrographic and microtectonic study and new geochronological, lithochemical and isotopic data, allowed the characterization of an anorthosite-mangerite association -rapakivi granite (AMG), Mesoproterozoic and its Paleoproterozoic host. Orthogneisses, foliated granitoids and charnockite rock bodies from the Serra da Prata Intrusive Suite show Pb-Pb (zircon evaporation) ages around 1.94 Ga, also inferred for the associated norites and gabbronorites. The Paleoproterozoic igneous suites were placed syn-kinematically, during Deformational Event D1, with the evolution of petroweaves indicative of high temperatures, from 600º-650ºC. These features include recrystallized feldspars by subgrain rotation, recrystallized perthitic alkali feldspars and quartz with checkerboard subgrains and have been observed in syn-plutonic dykes that cut the early-kinematic D1 fabric in the host country. The NE-NW arrangement of the Paleoproterozoic bodies was controlled by the previous structure of this sector of the Central Guiana Belt (CGC). The orthogneisses and foliated granitoids comprise two distinct suites, with lithochemical characteristics of type A granitoids, probably related to different oxidation conditions at the source. The charnockite rocks show chemical characteristics approaching those described for C-type magmatism. Sm-Nd TDM model ages between 2.19 Ga and 2.05 Ga, with ƐNd(T) values ranging from +0.68 to +2 ,47 suggested sources of limited crustal residence. The age of the orogenic events in Roraima has not yet been properly clarified, however, despite the limited data, a post-collisional positioning is proposed for the Paleoproterozoic suites studied after the accretion of transamazonian magmatic arcs. The Paleoproterozoic units constitute the basement of the Mesoproterozoic igneous suites, which comprise the anorthosites of the Repartimento unit and associated gabbronorites, the rapakivi granitoids of the Mucajaí Intrusive Suite (SIM), and the fine, porphyritic charnockites, of punctual occurrence and uncertain geochronological positioning. In SIM, three granite facies were identified (fayalite-pyroxene-quartz-mangerites to syenites; hornblende-biotite-granites; and biotite-porphyritic granites) geochemically and petrographically very similar to rapakivi granites from classical areas of Finland. The presence of fayalite in the most primitive rocks of the SIM indicates conditions of low oxygen fugacity, observed in several rapakivi granite complexes. Fine charnockites show no cpm to SIM chemical correlation. The Mesoproterozoic suites are part of an AMG (Anortosito-Mangerito-Granito rapakivi) association placed in an anorogenic environment between 1.54 and 1.53Ga. Model ages Sm-Nd, from 2.07 Ga to 2.01 Ga with ƐNd(T) values ranging from -2.37 to -1.27 suggest, for the granitoids in the association, crustal sources separate from the mantle in the Paleoproterozoic , probably during the Transamazônico. Mylonitic features related to the D2 Deformational Event, registering conditions of moderate to low temperatures (400º-450ºC), in a brittle-ductile environment, locally obliterate the igneous textures of the Mesoproterozoic units, as well as the high temperature D1 petrowebs in the Paleoproterozoic basement. These features are especially well developed in some shear zones that show dextral transpressive kinematics. The D2 event aged around 1.26 Ga relates to the K'Mudku Deformational Episode. The main D2 mylonitic zones were reactivated in the Mesozoic at shallow crustal levels and brittle conditions, during the evolution of Graben Tacutu.
Acesso aberto (Open Access)
Avaliação ambiental dos recursos hídricos, solos e sedimentos na área de abrangência do depósito de resíduos sólidos do Aurá - Belém-PA
(Universidade Federal do Pará, 2002-03-27) PIRATOBA MORALES, Gundisalvo; FENZL, Norbert; http://lattes.cnpq.br/6834981018643186
With 1.754.099 inhabitants, the municipality of Belém produces roughly 1,200 tons per day of all kinds of waste, which are deposited in a landfill known as Lixão do Aurá, bordering the municipality of Ananindeua. During the past 11 years, this area has been accumulating approximately three million and two-hundred thousand tons of solid waste, transforming that place into a permanent local source of anthropogenic pollution, altering environmental conditions and resources around the whole area surrounding it. A Vertical Electrical Resistivity Sounding (VERS) procedure, conducted in the area before it was transformed into the landfill (1991), compared with the measures taken eight years later (1998), show that the land resistance has considerably dropped, with values in some cases — 109 times smaller than the original ones, thus indicating that the layers have been affected by the leach from waste decay. Fifteen profiles were conducted in the area, using the electrical imaging system, allowing us to confirm the (VERS) results, with evidences that the underground water has been affected by the infiltration and by the leachate vertical and horizontal movements. The hydro geological characteristics in the area show that the local predominant type of aquifer is of the free kind, locally confined, with hydraulic gradient of approximately 0.695%, effective porosity of 28%, permeability coefficient ranging from 1.1 x 10-3 to 0.9 x 10-4 cm/s, and underground flows running north/south towards the Guamá River, at approximately 14.79 m/year. A multivariate statistical analysis has shown that superficial water samples, collected simultaneously at three control points, during one tide cycle, regardless of the season, portray totaily different behaviors, indicating that superficial water resources are being affected by the superficial movement of leachate. With the concentration value figures for each of the leachate parameters (pH, conductivity, alkalinity, ammonia, total organic carbon, chloride, sodium, potassium, calcium, and magnesia), plus the flow of the Aurá River at the control point near the Guamá River, it is possible to estimate the quantity of pollutants that the solid waste landfill sends into the water system. During one tide cycle, in the dry season, the solid waste landfill deposits approximately 13,115 kg of chloride, 417 kg of ammonia, and 129,767 kg of salts in the local water system. For the underground waters, the multivariate statistics showed that the samples collected In the monitoring wells in the area show significant differences, indicating that the wells located downstream have been affected by the leachate. The presence of sand layers right in the area where solid waste is deposited allows for the vertical and horizontal movement of the different pollutants originated by the leachate. The heavy metais anaiyses, conducted under the sequential extraction methodology, showed percentages in the geochemical phases potentially bio-available in the studied soil and sediment samples. In the soil samples, the potentially bio-available fraction (replace, reduce, and organic geochemistry phases) contained an average of 32% of the total Cadmium (Cd), 11.8% of the total Chromium (Cr), 23% of the total Copper (Cu), 12.32% of the total Nickel (Ni), 43.1% of the total Lead (Pb), and 31.01% of the total Zinc. The potentially bio-available phases percentage in the sediments of the area was greater than the ones found in the soil samples. In these sediments, the quantity of heavy metais in the potentially bio-available fraction, shown higher values during the dry season than during the rainy season; for instance, 33% of the total Cd measured during the rainy season increased to 37% in the dry season; Pb increased from 61 to 70%; Zn, from 51 to 54%, among others. The metais analyzed by total attack in the soil samples, compared with the sandstone backgrounds, indicate that the Fe (3.1%), Cu (18.5 ppm), Ni (10.1 ppm), Pb (69.5 ppm), Cr (76 ppm), and Cd (>1 ppm) are above normal standards. In the case of sediment samples, the EPA background values (total concentration) would be moderately polluted by Cr (average 64.6 ppm) and heavily polluted by Fe (3.8%) and Mn (600 ppm). These results show that the sediments were not polluted by Pb and Zn. Considering the potentially bio-available phase and using the tool provided by a Geographic Information System (GIS), we can say that, during the rainy season, the sediment samples were not polluted by Cr (potentially bio-available fraction smaller than 20% of the total) were highly polluted by Pb and Zn (PBD higher than 50%), and moderately polluted by Cu, Ni, and Cd (PBD between 20 and 50%).
Acesso aberto (Open Access)
Avaliação da contaminação por metais pesados em sedimentos por atividades de estaleiros na Baia do Guajará e no canal do Rio Maguari
(Universidade Federal do Pará, 2021-12-17) GUIMARÃES, Robledo Hideki Ebata; WALLNER-KERSANACH, Mônica; http://lattes.cnpq.br/7960214506412584; CORRÊA, José Augusto Martins; http://lattes.cnpq.br/6527800269860568
Antifouling paints applied on ships contain high concentrations of metals in their composition, mainly copper and zinc, with concentrations above 50% and 20%, respectively. Despite being essential elements for living beings, in high concentrations it causes problems in cell growth and reproduction of organisms. In the city of Belém, State of Pará, a significant amount of industrial and domestic effluents is released into the Bay of Guajará, one of which is related to activities in shipyards. Previous studies have shown evidence of metal contamination in the sediments in the edge of Belém estuary, however, no work has highlighted contamination from shipyards. Therefore, the objective of this work is to evaluate sediment contamination by activities in shipyards and abandonment of vessels in the edge of Belém city. The three samples of sediments were collected in 5 shipyards in Belém, two of which were collected in the less rainy period (September 2017 and November 2019) and one in the rainy season in May 2018. The sediment was collected up to 10 cm deep, and samples of paint fragments and fragments of the hulls of abandoned vessels were collected. The in situ pH of the interstitial sediment water was measured. In the laboratory, the sediment samples were placed in an oven at 60°C to dry, disaggregated and then sieved (< 63μm). The samples of paint fragments and the hulls of abandoned boats were washed with deionized water and dried in an oven at 60°C, macerated, mixed with the sprayed white area and reserved. A sample of the commercial paint most commonly used in shipyards was placed on a cellulose nitrate membrane in a hood, after which part of the sample was removed and macerated. An aliquot of the sediment samples from each shipyard was used for particle size analysis, using a laser particle analyzer. The mineralogical composition of the sediment samples was determined by X-ray diffraction, powder method. The clay minerals were determined by X-ray diffraction, following Stokes' Law and according to the methodology proposed by Moore & Reynolds Jr (2002). For the determination of total organic carbon, a TOC - VCPH analyzer with a combustion detector was used. To determine the concentrations of Cu, Zn, Pb, Ni, Cr, Ba, V, Li, Fe and Al contained in sediment, commercial paint, paint fragments and hull fragments of abandoned ships, the samples were subjected to chemical extraction with aqua regia and determined through Optical Emission Spectrometry with Inductively Coupled Plasma (ICP-OES). For statistical treatment of the data, Spearman's correlation was applied to determine the relationship between the parameters, and the Principal Component Analysis test to determine the relationship of metals with shipyards, control station and diffuse anthropogenic source station. The Wilcoxon test was also applied to verify if there were significant differences in the metal concentrations of the sediments collected in front of the shipyard with the sediments collected that were in contact with the abandoned vessel. To assess the level of contamination by metals, the geoaccumulation index proposed by Muller (1969) was applied. The sediment granulometry of the Belem shore presents a higher proportion of sand and silt. The sediments are composed of muscovite, illite, kaolinite, quartz and plagioclase. The clay minerals identified were: smectite, kaolinite, illite and quartz. The pH values of the interstitial water of the sediment samples from Baía do Guajará and Furo do Maguari were around 5.2 – 6.7. The total organic carbon of the sediment was around 0.6% to 2.2%. The commercial paint analyzed presented the following concentrations: Fe (21.2%), Cu (18,497 mg kg-1), Zn (16,589 mg kg-1) and Al (1.59%). The highest concentrations found in the composition of paint fragments and in the fragments of the hulls of abandoned vessels were: Fe (69.2 %), Ba (29,583 mg kg-1), Zn (9,350 mg kg-1), Pb (1,406 mg kg-1), Cu (697 mg kg-1) and Cr (548.7 mg kg-1). This result revealed that abandonment of vessels is the biggest source of contamination in shipyard areas in the city of Belém. According to the Sediment Quality Guidelines for Metals in Freshwater Ecosystems by Buchman (2008), only the average concentration of Cu, with 41.0 mg kg-1, in the sediment reached values above the Threshold Effects Level for the amphipod, Hyallela azteca (28.0 mg kg-1) in the ABSS shipyard. The other shipyards had copper averages ranging between 13.3 – 28.3 mg kg-1. The other metals had mean concentrations always below the Threshold Effects Level value. Spatially, the sediments that were collected in front of the ABSS shipyard for most metals had higher concentrations compared to the sediments that were in contact with the hull of the abandoned ship, of this shipyard. However, the sediments that were collected in front of the MS shipyard in general had lower concentrations compared to the sediments that were in direct contact with the abandoned vessel. Those that presented with concentrations of Cu (39.0 mg kg-1), Zn (120.0 mg kg-1) and Cr (32.0 mg kg-1) that exceed the value of Threshold Effects Level for the amphipod. However, the Wilcoxon Rank statistical test did not attest significant differences in the sediment collected in front of the shipyards with the sediment that was in contact with the abandoned vessels. The main elements that make up the antifouling paints: Cu, Zn had a strong positive correlation (r = 0.80; p<0.05). The Principal Component Analysis confirmed contamination by the metals Cu, Zn, Pb, Ni, Li, Fe and Al and has a stronger relationship with shipyard activities and ship abandonment than with diffuse geogenic or anthropogenic sources The geoaccumulation index classified the sediments close to the IS and ABSS shipyards as moderately polluted for copper with indices of 2.0 and 2.5, respectively. The other metals Zn, Ba, Fe and Al in the studied shipyards show an anthropogenic contribution by activities in shipyards and abandonment of vessels, classifying one or more shipyards as being in a situation close to a polluted environment, for one or more studied metals, with geoaccumulation index close to 2. The results can support additional studies of metal contamination through activities in shipyards and abandonment of vessels, and it can assist in the application of waste management in shipyards and ship cemeteries around the world.
Acesso aberto (Open Access)
Avaliação e aplicação de dados de sensores remotos no estudo de ambientes costeiros tropicais úmidos, Bragança, norte do Brasil
(Universidade Federal do Pará, 2000-11-17) SOUZA FILHO, Pedro Walfir Martins e; EL-ROBRINI, Maâmar; http://lattes.cnpq.br/5707365981163429
The study site is situated in the Cretaceous Bragança-Viseu coastal basin. The holocenic evolution of this area is marked by muddy progradation over a submerging coast, where is developed one of the most mangrove system of the world, with almost 6,000 km2. This research has showed that orbital remote sensing data can provide excellent geologic and coastal land use information. The SAR RADARSAT-1 imageries represent a powerful tool to understand the coastal processes in the wet tropical environments, mainly in the mangrove coasts. This fact is related to microwave radiation can be interpreted for Amazon coastal zone mapping and monitoring, because SAR image constitutes in the unique source of data with all-weather remote sensing capability, in response to difficulty to get optical images in the Amazon, due to all-time cloud cover. Landsat TM imageries are excellent data sources to integration with RADARSAT-1. They present a good performance in coastal environments discrimination. The remote sensing data integration allow a synoptic view of the area and provide geobotanic (relation between coastal environment and vegetation) and multitemporal information. In addition to integrated data, geographic information system (GIS) combines different data sets and simultaneously interprets the spatial and temporal relationship between various coastal environments. This way, GIS allows for a more comprehensive, accurate and easier interpretation of a geomorphologic mapping under an organizational philosophy to control data towards use the information to coastal zone management. The application of remote sensing data in the tropical coastal studies was used in different approaches. In relation to spatial and temporal variability of the shoreline, this study has revealed that during the Holocene, the coastal plain is marked by a muddy progradation. However, from the analysis of the remote sensing images were possible investigate the shoreline variability under long (1972-1998) and short (1985-1988, 1988-1990, 1990-1991) term, which is characterized by shoreline retreat, probably due to climatic changes, such as El-Niño and La-Niña events. These climatic events control the rainfall along the coastal zone, where severe erosional period (1985- 1988) are coupled with high precipitation rate (> 4,000 mm/yr.). From the point of view of the spatial analysis of the coastal changes, the mangroves constitutes one of the most environments to be analyzed by remote sensing images, as in the electro-optical spectrum due to their high reflectance in the infrared, as in the microwave due to their rough surface responsible for high backscattering. Therefore, mangroves have showed to be an excellent geologic indicator to detect and to quantify short and long-term morphological coastal changes. To conclude, remote sensing data integration, GIS and auxiliary fieldwork data present a fundamental role to the integrated coastal zone management, environmental risk assessment, local characterization of the study sites, base maps upgrading and information dissemination for public consultation, which are all significant factors in this decision-making process.