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Dissertações em Geologia e Geoquímica (Mestrado) - PPGG/IG

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2604

O Mestrado 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)
Análises sequenciais para o ouro em solo do salobo 3A, Serra dos Carajás
(Universidade Federal do Pará, 1989-06-07) FRANCO, Maria Esmeralda Bravo Esteves Bouça; RAMOS, José Francisco da Fonseca; http://lattes.cnpq.br/8189651755374537
The Salobo 3A area. in Serra dos Carajás in the State of Pará belongs to an elongated range. according to the WNW-E SE direction. of Archean age, which borders the northern flank of the Carajás syncline. This area has been the subject of several studies, with the aim of prospecting and extracting copper ores and using their by-products. The aim of this work is to investigate the distribution of gold in soils in the area of the Salobo 3A copper sulphide deposit. Eighteen samples were collected in horizontal and vertical profiles next to gallery G1 and another sixteen from wells PA-O8 and PA-23. Soil gold concentrations were determined according to the sequential partial opening of Gatehouse et al. (1977), which was supplemented by organic extraction. due to the low concentrations of this metal in soils. The phases considered separately were iron and manganese oxides and hydroxides (amorphous and crystalline), organic matter and clay mineral silicates and quartz. A particle size fraction < 120 mesh was chosen. to avoid the presence of larger metallic gold particles. In addition to sequential analysis. another 5 grams of the same sample were etched with HF+HCl04 and another 5 grams with HF+HCl04 followed by etching with aqua regia (Au-total). All results were compared with those obtained by the instrumental neutron activation analysis and with DOCEGEO analyzes performed through the aqua regia aperture. The main objective of this work is to show the suitability of sequential analyzes for gold in soils and, through the results obtained for the studied phases, to deepen the knowledge about the behavior of gold in a supergenic environment. Of these, it is worth noting the good correlation between the gold concentration determined in the organic matter and the Au-total concentration in the soil (or even only with aqua regia, or with values obtained by INAA). The study of the amount of organic matter related to the gold adsorbed on it seems to be in agreement with the mechanisms of mobility and transport of gold in a supergenic environment known so far. From the analyzes carried out, it is concluded that, in general, little gold is found in the native state, if the concentrations obtained by the partial extractions are compared with the Au-total concentration of the samples. This element is preferentially found in silicates (clay minerals and quartz), in organic matter and in goethite (in smaller amounts).
Acesso aberto (Open Access)
Aspectos mineralógicos geoquímicos da laterita niquelífera da área do Vermelho, Serra dos Carajás
(Universidade Federal do Pará, 1982-12-29) CORRÊA, Sandra Lia de Almeida; SCHWAB, Roland Gottlieb
The mineralogical-geochemical study of nickel-bearing laterite from the Vermelho area, Serra dos Carajás, was based on 64 samples obtained from a drill in the mother rock and a well in the alteration profile. The lateritic profile, developed on serpentinized ultrabasic rocks, consists of three distinct horizons; from the base to the top: saprolithic horizon, with more than 4 meters of thickness, clayey horizon, with 6.1 meters, and limonitic horizon with 8.3 meters. Mineralogically, the saprolitic horizon consists of serpentine, chlorite, quartz, hematite and goethite, the clayey horizon of smectite, chlorite and goethite and the limonitic horizon of quartz, goethite, hematite, chlorite and kaolinite. Maghemite is present from the base to the top of this profile. During the action of weathering, the main and trace elements underwent leaching, transport and reprecipitation processes, resulting in the concentration of these elements in the different horizons of the profile, with the exception of magnesium, which was leached to a large extent. Despite the low mobility of chromium in the lateritic medium, this element was leached from the saprolitic horizon and from there it enriches itself, thus behaving as a relatively mobile element. The profit and loss calculations were difficult to make because no element showed continuous relative enrichment from the bottom to the top of the profile. Considering the average contents of the horizons of the lateritic profile and fresh serpentinite, only iron and cobalt present continuous relative enrichment. The nickel concentration in the clayey horizon possibly occurred through an ion exchange process between the smectite and the level migrated by descending solutions, after its release from goethite. The parent rock contains 0.3% Ni, while the clayey horizon has an average content of 4.5% Ni. Cobalt and zinc were also strongly enriched during the laterization process. The cobalt was concentrated in the limonitic horizon, where it reaches an average content of about 0.1% by weight, thus suffering an enrichment of almost nine times in relation to its content in the mother rock. The distribution of cobalt in the lateritic profile is controlled by iron and manganese minerals. Zinc was concentrated in the saprolitic horizon, where it has an average content of approximately 0.05% by weight, enriching about 10 times its content in the mother rock.
Acesso aberto (Open Access)
Aspectos termodinâmicos relacionados com a gênese e alteração de minerais de cobre em clima tropical úmido (região da Serra dos Carajás-PA
(Universidade Federal do Pará, 1990-01-14) FERREIRA, Rosângela Sales; LIMA, Waterloo Napoleão de; http://lattes.cnpq.br/1229104235556506
Copper deposits belonging to the volcano-sedimentary sequence (Salobo 3 A and Bahia) and the Serra Verde supergenic enrichment deposit are objects of study in this work, located in the Carajás Mineral Province (Municipality of Parauapebas, State of Pará). For chemical-mineralogical characterization, we proceeded: (1) X-ray diffractometry; (2) chemical analysis (colorimetry and atomic absorption spectrophotometry); and (3) the use of stoichiometric calculation, providing data capable of contributing to the clarification of the geochemical behavior of copper species and associated minerals in weathering profiles. In order to examine in more detail the geochemical changes inferred in the geological environments of the three deposits (Salobo 3A, Bahia and Serra Verde), a theoretical study was carried out on thermodynamic parameters, compiled in the literature, and such data were manipulated in the calculation of free energies. of Gibbs and of the equilibrium constants of the reactions for the considered chemical systems. This study involved the equilibrium relationships between the minerals biotite (Fe), chlorite (Fe), montmorillonite (Fe), tremolite (actinolite), kaolinite, geothite, pyrite, chalcopyrite, bornite, brochantite, azurite, malachite and pseudomalachite, from the copper deposits in the Serra dos Carajás region. The objective was the elaboration of stability diagrams of these minerals. A brief experimental study was also carried out, by carrying out measurements of Eh and pH, in the laboratory, by dissolving the sampled material in distilled water, in order to frame such data in an Eh-pH diagram, existing in the scientific literature. , in an attempt to obtain information about the acidic, basic, oxidizing and reducing characteristics of the species contained in the samples under study. The theoretical thermodynamic study concerns the applicability of calculations related to the solubility product and the Gibbs free energy. The final composition resulting from the joint use of the experimental work with the theoretical investigation allowed to verify the stabilities of the detected mineral species, being possible to confirm the field observations. For Serra Verde, the thermodynamic calculations clearly demonstrated that the stability of the detected supergenic copper minerals grows in the order malachite-azurite-brochantite-pseudomalachite. The reactions suggested in the work reveal that both bornite and chalcopyrite underwent alterations in an oxidizing medium (positive and somewhat high Eh), producing the aforementioned supergenic minerals. For Salobo, this study shows the possibility of determining the stability fields of primary and altered silicates from the copper host rock, as well as the stability fields of copper and iron sulphides (bornite and chalcopyrite), enabling the formation of brochantite, which occurs locally in the study area. For the occurrence of Bahia, the stability field was determined in the same way as for Salobo, with chalcopyrite being found there in a disseminated form.
Acesso aberto (Open Access)
Avaliação ambiental da matéria orgânica degradada nos canais de drenagem da região metropolitana de Belém (PA)
(Universidade Federal do Pará, 1997-01-14) SANTOS, Maria Tereza Primo dos; LIMA, Waterloo Napoleão de; http://lattes.cnpq.br/1229104235556506
Acesso aberto (Open Access)
Avaliação da distribuição das concentrações de mercúrio total em sedimentos, rejeitos, solos e solos com TPA, na bacia do rio Rato-Itaituba/PA
(Universidade Federal do Pará, 1995-08-20) SOUZA, Jorge Raimundo da Trindade; RAMOS, José Francisco da Fonseca; http://lattes.cnpq.br/8189651755374537
The rio Rato located in Itaituba, SW of Pará State, is the principal mercury mining center of the region. The surveied stretch of approximatly 60 km, suffers a great environmental impact, due to gold mining activities. Two field campaigns were conducted and 161 samples were collected for analysis. Total mercury content was determined by cold vapor atomic absorption (CVAS), prior to chemical diggestion with H2SO4, HNO3 and V2O5. The mercury concentration was determined in stream sediments, mining tailings, soils and black earth archeological soils. Organic carbon and loss on ignition (LOI) were also determined to correlate with mercury data. Statistical parameters, such as minimum, maximum, average and standard deviation were used to evaluate the pollution degree of the area and also for comparison with data from other studies. Samples were distributed in seven groups according to field campaign period, type of sample and sample site. For all types of samples, the results obtained from the first field campaign were higher than those from the second campaign, indicating that mining activities are more intense during the dry season. Significant correlation between mercury concentrations and other two variables (organic carbon and LOI) was observed only in a few sample. This observation support the alleatority of the contaminations, and shows that mercury distribution depends on the type of explotation, season, granulometry and sample location. Most samples show mercury concentrations greater than the regional background, which represents a general enviromental contamination.
Acesso aberto (Open Access)
Avaliação geoquímica da contaminação por mercúrio dos sedimentos de correntes e solos do distrito mineiro de Zaruma-Portovelo, república do Equador
(Universidade Federal do Pará, 1996-05-31) MALDONADO RAMIREZ, Roque Vicente; RAMOS, José Francisco da Fonseca; http://lattes.cnpq.br/8189651755374537
Auriferous occurrences are known in the area of Zaruma-Portovelo, Ecuador, since the pre-Columbian period, but it was only from the end of the 70's that a very intense mining activity started to be developed. Miners in the sector carry out the activities of exploration, exploitation and processing of polymetallic ore using rudimentary techniques, which causes contamination of rivers, soil and atmosphere by mercury and other heavy metals, in addition to cyanide. They still deforest the area, as they use wood in the security structures of the mineral galleries. The deposit in the mining district of Zaruma-Portovelo is of hydrothermal, polymetallic origin, occurring in a complex of andesitic volcanic rocks of the Celíca Formation. The ore is composed of the sulphides pyrite, chalcopyrite, galena, sphalerite and bornite, among others, in addition to the gangue minerals quartz and calcite. The metals Cd, Zn, Pb and Cu are released from these minerals. Mercury is of anthropogenic origin, as it is used in the extractive metallurgy of gold, as is cyanide, which is used in a second phase of the gold recovery process. The present work had as objective the identification and geochemical evaluation and the description of the activities of the sources of pollutants, especially mercury, through the collection and analysis of samples of bottom sediments, soils and mining tailings, in addition to making a brief description of the activities from the mine. A sampling campaign was carried out at the end of the dry season, having collected 26 samples of bottom sediments, 23 of soil and 4 of tailings. At 5 points soil samples were taken in profiles with intervals of 2 cm to a depth of 14 cm. A study of the distribution of metals in the different granulometric fractions of the sediments was also carried out. Samples were collected in triplicate at three points to determine the variability of the results. The concentrations of Hg(total) in soils indicate that 83% of the samples are above the background (103ppb) with minimum and maximum values of 109 and 9,546 ppb and an average of 662 ppb, with the highest concentrations occurring in samples close to the emission sources, which are the mills (processing plants). In all profiles, it was found that the highest levels occur in the upper part, gradually decreasing with depth. In the bottom sediments, in addition to Hg(total), the elements Pb, Zn, Cd and Cu were analyzed in the exchangeable fraction, observing anomalous values for all these anomalous values concentrated mainly in the drainages of the Calera and Amarillo rivers, after the junction with the Calera River, which has most of the area's processing plants on its banks. High levels of Hg, Zn, Pb, Cd and Cu were observed in the mining tailings samples, confirming that artisanal beneficiation processes, in addition to generating pollution, cause economic losses due to the low recovery of metals. Tests to verify the amounts of mercury used by miners for amalgamation show that 95 to 97% of the mercury is released into the atmosphere in the amalgam burning stage. The rest is released in liquid form in the soils and drainages of the area. This shows the importance of developing an education policy for prospectors, offering new alternatives and technologies to avoid the burning of amalgam in the open air, which would greatly contribute to the reduction of mercury contamination.
Acesso aberto (Open Access)
Balneabilidade das praias estuarinas da Ilha de Mosqueiro (PA): uma visão geoquímica ambiental
(Universidade Federal do Pará, 1995-09-21) DIAS, Lianne Maria Magalhães; BRAZ, Vera Maria Nobre; http://lattes.cnpq.br/1729944237086176; LIMA, Waterloo Napoleão de; http://lattes.cnpq.br/1229104235556506
Acesso aberto (Open Access)
Caracterização geoquímica das drenagens afetadas pelo beneficiamento de ouro no distrito aurífero de Ginebra, departamento del Valle Del Cueda, Colômbia
(Universidade Federal do Pará, 1995-10-30) RAMOS, Jader Muños; RAMOS, José Francisco da Fonseca; http://lattes.cnpq.br/8189651755374537
The gold-bearing district of Ginebra shows regionally three well defined geological units: the Amaime formation (tectonized pillow-laves), the ophiolitic massif of Ginebra (sequency of peridotites, gabros, metabasalts, plagio-granites and micro-breccias) and the Buga”s batolith (quartz diorite varying to tonalite). The Buga”s batolith intrusion in the ofiolitic massif of Ginebra produced a hydrotermal alteration and a gold bearing sulfide mineralization in the contact zone, resulting a stockwork-like gold-bearing deposit surrounded by gold-bearing veins. The local miners have explored and exploted the district for almost a century, using rudimentar tecniques. A part of the ore and the tails are dispersed by gorges flowing into the Guabas river, from where the water for the municipal aqueducts of Ginebra e Guacarí is taken. This 1s the importance of this study. To obtain the geochemical evaluation of the heavy metal levels in the drainages of the zone, 27 water samples were collected in the district and analysed for As, Au, Co, Cr, Cu, Fe, Mn, Ni and Pb. Aditionally, 28 sediment samples (27 of stream sediments and 1 of suspension sediment) from the same zone were analysed for Ag, As, Au, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn. The statistical treatment applied to the results showed local anomalies related to the dispersion of mining tails. 4 Anomalous concentrations for As, Au, Co, Cr, Cu, Fe, Mn, Ni and Pb, as metals in solution in the waters, were detected near to the input of the effluents of mine to the gorges, due to a decay of the pH by oxidation of the sulfides within it. The pH background, varying from slightly basic to basic, is a geochemical barrier that decreases the anomalous concentrations of metals to normal levels in the waters, increasing their concentrations in the sediments. The stream sediments showed local anomalies for As, Au, Co, Cu, Hg, Mn, Ni, Pb and Zn. The mercury detected in the district has an antropogenic source. This metal is used for gold amalgamation. Dangerous emissions of mercury to the stream sediments and the air are released by losses of amalgama”s recoverying and amalgama”s burning (to recover the gold). The airbomne transport of mercury was deduced by the observation of a vertical variation of the Hg concentrations in the soils. The possibility of higher antropogenic changes on the pH and Eh conditions in the waters of the district gorges, the mechanical remobilization of the sediments with high heavy metal concentrations and the airborne transport of mercury justify a continuous monitoring of the concentrations of heavy metals in solution in the waters for domestic use at the municipalities of Ginebra and Guacarí and the suspension sediments within it. These analysis must be accompanied by technical directions for the use of mercury and recovering of gold, for the miners of the district, minimizing the environmental agressions.
Acesso aberto (Open Access)
Caracterização mineralógica com espectroscopia de reflectância por infravermelho (SWIR): exemplo do Complexo máficocarbonatítico Santana, sul do Cráton Amazônico
(Universidade Federal do Pará, 2021-09-21) COSTA, Jhoseph Ricardo Costa e; FERNANDES, Carlos Marcello Dias; http://lattes.cnpq.br/0614680098407362; https://orcid.org/0000-0001-5799-2694
On the border of the Pará and Mato Grosso states, in the Amazonian Craton, municipality of Santana do Araguaia (PA), there is a volcano-plutonism named Santana mafic-carbonatitic complex. This set houses the Serra da Capivara phosphate deposit. A lower mafic-ultramafic member reveals plutono-volcanic lithofacies with pyroxenite, ijolite, apatitite, and alkaline basalt. Autoclastic lithofacies contains poorly selected deposits of massive polymictic breccia, lapilli-tuff, crystal tuff, and ash tuff. Volcanogenic epiclastics rocks cover these lithofacies. The upper carbonatite member contains plutonic lithofacies with coarse calcite-carbonatite (sövite). Fine carbonatite veins with pervasive carbonatic and apatitic alterations crosscut this lithotype. Minor thick apatitite occcurs associated to this member and represents the protore of the deposit. Effusive volcanic lithofacies reveals fine calcite-carbonatite (alvikite) with porphyritic, equigranular, or aphanitic textures. A poorly sorted lithofacies of crystals tuff, lapilli-tuff, and massive polymictic breccia completes this member. Stocks and syenitic dykes invade these lithofacies. Detailed mapping suggests that the complex is a volcanic caldera in which large zones of hydrothermal alterations occur with reddish, brownish red, and yellowish carbonatitic rocks. Petrographic observations reveal paragenesis of barite + fluorapatite + calcite + dolomite ± quartz ± rutile ± chalcopyrite ± pyrite ± monazite ± magnetite ± hematite. The application of short wave infrared spectroscopy (SWIR) revealed the chemical characteristics and their importance in the crystallinity of most of these hydrothermal minerals, such as radicals (OH- and CO3), H2O molecule, and cation-OH bonds such as Al-OH, Mg-OH, and Fe-OH. The main mineral phases identified were dolomite, calcite, serpentine, chlorite, muscovite with low, medium, and high aluminum, montmorillonite (Ca and Na), illite, nontronite (Na0.3Fe2((Si,Al)4O10) (OH)2·nH2O), and epidote. The data suggest a control by temperature, fluids composition, and fluid/rock ratio during the evolution of the Santana mafic-carbonatitic complex. This low-cost exploratory technique, which is applied in hand-held samples or drill holes on a large scale, is promising in characterization of volcano-plutonic centers in regions subjected to severe weathering conditions, as well as helping to develop models for prospecting mineral deposits of Rare Earth Elements (e.g. Nd, La) associated with alkaline-carbonatitic complexes. We can even combine this tool with artificial intelligence algorithms for more robust and faster results.
Acesso aberto (Open Access)
Contaminação no lago Xolotlán causada pelos despejos vertidos pela área metropolitana da cidade de Manágua, Nicarágua
(Universidade Federal do Pará, 1995-05-25) ALBUQUERQUE ESPINOZA, Noemi Marlene; FENZL, Norbert; http://lattes.cnpq.br/6834981018643186
Lake Xolotlán, the smaller of the two large lakes that occupy the Nicaraguan Depression, has been polluted by the metropolitan area of the city of Managuá since 1928, when it began to be used as a receiving body for the city's sewage. It currently also receives wastewater from the main industries in Nicaragua (located in Managua); sediments, garbage, high content of nutrients and organic pollutants from the drainage basin and the water that percolates from the main dump in the city of Managua (Lixão Acahualinca). To determine the levels of contamination by chromium, copper, arsenic, cadmium, mercury and lead on the southern coast of Lake Xolotlán, two sampling campaigns were carried out in six profiles with a north direction, starting from the discharge points of three sanitary sewage collectors, an industrial wastewater effluent, a rainwater drainage channel and in front of a "sanitary" landfill. In the first campaign, sampling was carried out up to a distance of 1000 meters from the lake shore and in the second, up to 500 meters. Water and sediment samples were collected for the analysis of trace elements and water samples for the determination of physical and physical-chemical variables. A third sampling campaign was carried out on two profiles to determine the concentrations of ƩDDT and toxaphene in sediments from Lake Xolotlán. For the determination of trace elements, the atomic absorption spectrometry method was used. ƩDDT and toxaphene were determined by the gas chromatography method. In the analysis of physical and physical-chemical variables, descriptive methods by APHA (1992) were used. The concentrations of chromium, copper, arsenic and cadmium in water were lower than the limits established by the National Council for the Environment (CONAMA) of Brazil in 1987 for brackish water intended for primary contact recreation, the protection of aquatic communities and the creation of species. intended for human consumption. Lead was exactly at the limit established by CONAMA for this pollutant (10ppb) at the point of discharge of the influent sampled from industrial wastewater in the first sampling. Mercury concentrations in water were high throughout the wastewater effluent profile, ranging from 0.6 to 0.1 ppb in both samples. In sediments from the coast of Lake Xolotlán, chromium was found at an average concentration of 15.1 µg/g and its distribution in most profiles indicates contamination by point sources, similarly to what occurs with copper (57 - 28 µg/g) and arsenic (1.3 - 11.2 µg/g). Cadmium contamination (0.7 - 4.7 µg/g) is a product of volcanic activity. Sediments sampled at the point of discharge of the sampled wastewater show a strong mercury contamination (57.6 µg/g), which decreases with distance. In turn, lead contamination (average concentration of 36.8 µg/g) is widespread throughout the study area and, with the exception of one profile, its spatial distribution indicates contamination by non-point sources. Toxaphene was only detected at the industrial wastewater discharge point, but the concentration was high (10 ppm). The distribution of ƩDDT suggests contamination by an unidentified point source. The results of the analysis of the physicochemical variables demonstrate that the volcanic activity is contributing with high values of Ph, solids, boron, fluorides and higher ion concentrations. The significant decrease in the concentration of nutrients and the chemical and biochemical oxygen demands, with the distance from the point contamination sources, reveal that Lake Xolotlán has a high stabilization capacity.
Acesso aberto (Open Access)
A Distribuição dos elementos Cu, Au, Co, Zn, Ni, Mn, e Fe em solos sobre o depósito de Cobre de Salobo -3A, Serra dos Carajás
(Universidade Federal do Pará, 1985-10-04) HERRERA, Marco Túlio Guillen; RAMOS, José Francisco da Fonseca; http://lattes.cnpq.br/8189651755374537
Acesso aberto (Open Access)
Estudo da qualidade da água e abastecimento da zona urbana de Belém (PA), aplicação à problemática existente no bairro do Jurunas
(Universidade Federal do Pará, 1985-10-04) BRAZ, Vera Maria Nobre; LIMA, Waterloo Napoleão de; http://lattes.cnpq.br/1229104235556506
The present work aimed to evaluate the quality of the water consumed in Belém, mainly in areas where sanitary conditions were deficient. For this purpose, the Jurunas neighborhood was chosen as the study universe, which presents itself with extensive areas of "lowlands", lacking in sanitation. The water quality was verified through physical-chemical and bacteriological analyses. The analyzed samples were classified according to the potability standards of the World Health Organization, through a computer program. Trace elements such as Ni, Co, Cu, Cr, Pb, Mn and Al were also studied by themeelectric atomic absorption spectrometry, a study that had not been done before in the waters that supply the City. In the experimental phase, four samplings were carried out, distributed in the months of May, August, November 1983 and February 1984, so that the seasonal variations that might occur could be detected. The collections were carried out in ten points, representative of the entire neighborhood. In order to characterize the environment, aspects related to geology, geomorphology, climate, vegetation, soil and hydrology of the City were approached. On the other hand, considerations were made about the springs, the water treatment system and the supply and sewage networks. In particular, we sought to correlate the sanitary conditions of the lowlands with the occurrence of waterborne diseases. According to the results of the analytical determinations, it was verified that most of the physicochemical parameters studied were compatible with the potability standards. Exceptions were constituted, pH, conductivity, chlorides, iron and aluminum, whose values extrapolated the recommended ones, mainly those referring to the month of November of 83, period in which there was a strong drought in the region, which caused salinization of the waters of the springs and of supply. Regarding the bacteriological parameters, 34% of the values were outside the criteria recommended by the WHO, thus constituting one of the most significant problems detected in the analyzed waters. The results obtained were probably due to the conditions of the distribution network in the neighborhood, as well as the hygienic conditions in some collection points; the presence of bacteria in the water is the cause of numerous diseases, and some of their symptoms were detected in the population residing in the neighborhood, during the associated sampling.
Acesso aberto (Open Access)
Estudo de águas destinadas ao consumo da população das baixadas da cidade de Belém-PA (bairro da Sacramenta): avaliação da qualidade sob os aspectos físico-químico, bioquímico e bacteriológico
(Universidade Federal do Pará, 1985-10-04) MENEZES, Lúcia Beckmann de Castro; LIMA, Waterloo Napoleão de; http://lattes.cnpq.br/1229104235556506
Acesso aberto (Open Access)
Estudo geológico e aspectos econômicos de um depósito de esmeralda clássico, Socotó-BA
(Universidade Federal do Pará, 1990-12-17) COLLYER, Taylor Araújo; KOTSCHOUBEY, Basile; http://lattes.cnpq.br/0096549701457340
The world trade in gemstones, which today involves values of around 80 billion dollars/year, dates back to millennia, having had a great influence on the development of human civilization. Emerald occupies a prominent place in this trade, and Brazil, with large gemological provinces, is an important source of this mineral. The Brazilian production, with approximately 80 tons/year of raw emerald, is favored by the relative political and social stability of the country, which constitutes an advantage in relation to other producing countries. On the other hand, the export of raw gemstones, the absence of a mineral and research policy in this sector, prevent the generation of greater resources, benefiting only small groups, usually foreigners. The present work aims to show that the Socotó emerald deposit, due to its classical characteristics, can serve as a model in view of prospecting in other areas with a similar geological environment, as well as to allow the clarification of some questions related to the formation of this mineral. The geological framework of Socotó mainly consists of an intensely fractured/failed basal-ultrabasic rock body, corresponding to a "roof pendant" or a mega-enclave embedded in the Campo Formoso granite batholith. The intrusive magma of granitic composition, rich in molybdenum, volatile elements and beryllium, reacted with the meta-ultrabasic rocks; suppliers of the chromophore elements Cr, Fe and V, which resulted, along dikes and veins, in abundant emerald mineralization controlled by geochemical, physical and structural factors. An intense metasomatism allowed the development of at least three concentric zones in the contact aureole, characterized by specific mineral associations, namely: an external zone, an intermediate zone and a more internal zone in the enclave. Through geophysical survey by scintillometry and magnetometry, the shape and the following dimensions were defined for this enclave: 2,150 meters long, 180 to 335 meters wide and a thickness of up to 161 meters. The analysis of the remaining magnetization showed the thermal evolution of the granitoids, from their placement 1973 ± 24 m.a ago (Torquato et al, 1978), to the closing of the mineralizing cycle 1784 ± 47 m.a., age obtained by the Rb/Sr method in phlogopites associated with emerald. Finally, the recognition of the different types of inclusions and the large amount of growth tubes and channels along the C axis of emerald crystals, whether or not filled with minerals, allowed the prediction, with economic objectives, of conventional or complex chemical treatment, involving the application of a laser beam and the displacement of atoms along these natural filaments.
Acesso aberto (Open Access)
Estudo hidrodinâmico e sedimentológico do Estuário Guajará - Belém (PA)
(Universidade Federal do Pará, 1987-08-22) PINHEIRO, Roberto Vizeu Lima; FARIA JUNIOR, Luis Ercílio do Carmo; http://lattes.cnpq.br/2860327600518536
This work presents the hydrodynamic and sedimentological characteristics of the Guajará Estuary, in the vicinity of the city of Belém. Its approach covers geological and geomorphological aspects, the behavior of waves, winds, tides, tidal currents and the investigation of the physical-chemical parameters of the waters, with the objective of sketching a quantitative model for this environment in addition to presenting a proposal for the evolution region physics. From the oceanographic point of view, the Guajará Estuary is characterized by the absence of marked thermal stratification, being classified as partially mixed, type B in the Pritchard classification (1955), with appreciable lateral variations in salinity. It is subject to a circulation mechanism controlled by strong tidal currents, which define easily individualized flood and ebb channels. Two main wind systems are responsible for the formation of several sets of waves with characteristics that will depend on their speed, intensity, duration time and direction in relation to the geography of the estuary. The tides and tidal currents interfere decisively in the formation of waves. The dynamic tide has an average amplitude in syzygy and quadrature, in the Port of Belém, around 3.0 m and 2.5 m respectively. The tidal currents on the surface, during the moments of change of direction, show a complex mechanism of circulation, always obeying the characteristics of individualization of the flood and ebb channels. The salt tide inflow mechanism also follows this pattern. Conductivity proved to be the most important parameter for defining the salt tide intrusion mechanism. Important variations in the average values of pH, O2 concentration, concentration of suspended material and conductivity in estuarine waters follow, approximately, the seasonal variations during the year marked by very rainy periods followed by the dry season. Hourly variations during tidal cycles, as well as variations arising from the fortnightly movements of the Moon (syzygy and quadrature) are similarly important. The water temperature follows the air temperature variations in the region, with expressive daily amplitudes. The Holocene sediments that fill the estuarine trough are predominantly sandy, ranging from selected to well selected, sometimes silty. The sedimentation is marked by the hydrodynamic conditions of the environment, being recognized two important textural facies: Muddy Facies and Sandy Facies. The distribution of these textural facies apparently oscillates as a function of tidal periodicity. The pelitic fraction of the estuarine sediments is composed of kaolinite, illite, smectite and stratified illite-smectite, with traces of chlorite still occurring. In the sandy fraction, quartz is the main mineral in association with iron oxide grains. Among the transparent heavy minerals, staurolite, tourmaline, kyanite, zircon, epidote and amphiboles predominate, in addition to garnet, rutile and andalusite. As main source areas, the Tocantins and Guamá rivers are pointed out. In addition to these, the Barreiras Group and the Holocene Lands must supply the estuarine bed with sediments. A geological-geomorphological evolutionary model for the Guajará Estuary is proposed, assuming the age of its implantation from the Lower to Middle Holocene, associated with the manifestations of the Flandrian Transgression.
Acesso aberto (Open Access)
Hidrocarbonetos Policíclicos Aromáticos em Microplásticos de Praias do Litoral Brasileiro
(Universidade Federal do Pará, 2021-07-30) BRANCO, Felipe Ohade Lopes; CORRÊA, José Augusto Martins; http://lattes.cnpq.br/6527800269860568
When introduced on the environment, plastic materials might have many destinies, and one of them is the fragmentation. The continue degradation and fragmentation of the plastic materials originates the called microplastics (MP), particles with sizes between 5 mm and 1 μm of a great potential of dispersion. When in polluted environments microplastics tend to become adsorption superficies for hydrophobic pollutants more efficiently than natural solid particles, as Polycyclic Aromatic Hydrocarbons (PAH). PAH are organic pollutants that might have its origin from natural and anthropic processes. In the same way as microplastics, PAH are highly persistent in the environment, and for presenting mutagenic and potential carcinogenic properties when absorbed by human and aquatic organisms metabolisms they are extremely dangerous. Due to its toxic and harmful properties to environment and human health, sixteen PAH are defined as priorities in environmental studies by the United States Environmental Protection Agency (US EPA). Several studies have evaluated the occurrence of microplastics and PAH individually in environmental matrices, but still are few that investigated the association of these two pollutants. In this way, especially in Brazil, there is a need of expansion of research about this theme. The present study has the aim of investigate the occurrence and concentration of PAH in microplastics in beach sediments from eight Brazilian coastal states, to verify its composition and possible sources of the compounds to MP in the studied areas, to relate the accumulation of MP and PAH considering the land use and social-environment factors of each region, and to evaluate the toxic potential and of contamination of PAH from MP to aquatic organisms. Sediment samples were taken from the high tide mark from potentially polluted locals from the beaches of Ver-o-Rio and Farol (PA), Iracema (CE), Boa Viagem (PE), Porto da Barra (BA), Curva da Jurema (ES), Arpoador and Botafogo (RJ), Praia Grande, Santos and São Vicente (SP), and Praia Grande (RS). On the laboratory using a hypersaline solution and a filtration system, MP were separated from the sediments. PAH were extracted using three types of microplastics, 0,2-0,3 g of fragments and pellets, and 0,02 g of EPS (foam), and were analyzed in Gas Chromatography Tandem Mass Spectrometry (GC/MS/MS). It was possible to detect fourteen of the sixteen studied PAH, where the total concentration of PAH (Σ-PAH) varied between 0,25 to 71,60 ng g-1 on the samples and types of MP. On the North and Northeast regions, the low concentration (0,31 to 71,60 ng g-1) of PAH in MP appears to be related to the intense hydrodynamic processes. The concentration of Naphthalene on the foam samples were above the Threshold Effect Level (TEL > 35) on the samples from Pernambuco and Bahia, e near of TEL at Ceará (70,15, 36,97 and 33,28 ng g-1, respectively); so, effects in the organisms might occur due to this compound. The Southeast and South regions are the only that presented previous studies of PAH in MP, so it was possible to make a better comparison and discussion of the obtained data from the present study. The sources of PAH for the environment and consequently for MP were attributed to the anthropogenic contribution (petrogenic and pyrogenic). The highest concentration of PAH was found in the foam samples, suggesting that this type of MP might have a considerable contribution in the dispersion of these contaminants, especially in more polluted locals. Lastly, its concluded that PAH are present on all the Brazilian states studied and its occurrence were evidenced by its adsorption in MP sampled in beach environments. The organic contaminants originate both from petrogenic and pyrogenic processes, and the principal sources of these compounds to the evaluated locals were industrial and port activities, the inadequate disposal of effluents, and the urban runoff by pluvial waters.
Acesso aberto (Open Access)
Implantação da metodologia U-Pb em monazita por LA-ICP- MS no Laboratorio de Geologia Isotópica da UFPA (Pará-Iso): aplicação em rochas de alto grau metamórfico da região central do Amapá, Sudeste do Escudo das Guianas
(Universidade Federal do Pará, 2022-06-15) FERREIRA, Dominique de Paula Amaral; LAFON, Jean Michel; http://lattes.cnpq.br/4507815620234645
The objective of this dissertation was the implementation of the experimental procedure of the U-Pb methodology on monazite by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) at the Pará-Iso/UFPA laboratory. Monazite is an orthophosphate of light rare earth elements which occurs in several types of igneous and metamorphic rocks. Its resistance to metamictization and high closure temperature for Pb (~750-900°C - Parrish 1990; Cherniak et al. 2004) make it an important tool to provide timing of high-grade metamorphic events using U-Pb geochronology. Sample preparation procedure for monazite separation and concentration was adapted from that used for analyzes in zircon, taking into consideration the monazite specifities (mainly magnetic susceptibility). After crystal selection and making the mounts with epoxy resin, Backscattered Electron (BSE) images were obtained to assess internal structures and to select the sites in the monazite for isotopic analyzes by Neptune Thermo Finnigan ICP-MS equipped with a CETAC Nd: YAG 213 nm laser microprobe model LSX-213 G2. The raw data reduction was processed using an inhouse Excel spreadsheet, adapted for monazite data processing. Age calculations were performed with the Isoplot/EX. Initially, we analyzed two international reference materials (Bananeira and Diamantina monazites) to evaluate precision, accuracy and reproducibility of the analytical data. In addition, we evaluate as a potential reference material (RM) a sample of monazite from a Neoproterozoic pegmatite from eastern portion of the Araguaia Belt, state of Tocantins. Bananeira and Diamantina monazite analyzes by LA-ICP-MS provided ages of 510 ± 5 Ma (207Pb*/235U 238U weighted average age, n = 27, 95% conf., MSWD = 0,089) and 495 ± 2 Ma (206Pb*/238U weighted average age, n = 47, 95% conf., MSWD = 0,995) respectively, similar to the ages of 508 ± 1 Ma and 495 ± 1 Ma obtained by ID-TIMS, LA-QICP- MS and LA-SF-ICP-MS for these respective RMs. The higher intensity of the analytical signal of the Bananeira monazite got it elected as the primary MR and the Diamantina monazite as the secondary MR. BSE images and compositional maps highlighted the homogeneity of the Xambioá monazite. Analyzes by LA-ICP-MS provided 206Pb*/238U weighted average age of 514,3 ± 2,3 Ma (n = 27, 2σ, MSWD = 0,56), compatible with the regional geological framework. These data need to be validated by inter-laboratory comparison, however this monazite showed potential as an internal laboratory MR considering the size of the crystal available (7 cm length, ~180 g). Next, a first application of the U-Pb methodology on monazites by LA-ICP-MS supplied a reliable age for the highgrade metamorphism of Paleoproterozoic rocks from the Tartarugal Grande granulitic complex (CGTG), in central state of Amapá, southeastern Guiana Shield. For interlaboratory comparison, a sample was also analyzed at the LA-ICP-MS Laboratory of the Research Unit Géosciences-Montpellier at the University of Montpellier, France. Monazites from two Rhyacian garnet-biotite gneisses from CGTG (HP-17 and HP-04) and neosome derived from them (HP-09C) were analyzed. Studies estimated granulite facies conditions with temperature of 800° ± 20 °C and pressure of ~7 Kbar for the metamorphism of these rocks. U-Pb isotopic analyzes on monazites from sample HP-17 provided upper intercept ages of 2058 ± 19 Ma n = 51, MSWD = 0,64; Pará-Iso) and 2037 ± 4 Ma (n = 15, MSWD = 0,098; Montpellier) therefore similar within the error. The monazites from sample HP-09C provided a 207Pb/206Pb weighted average age of 2058 ± 7 Ma (n = 30, 2σ, MSWD = 0,15). These ages are interpreted as age of the granulitic metamorphic peak. The monazites of sample HP-04 presented a spreading of the analytical points along Concordia curve, with 207Pb/206Pb dates ranging from 2096 to 2056 Ma. These dates may depict a prolonged growth interval for the monazite during metamorphism or a partial to total reseting of the U-Pb system of monazite from the magmatic protolith during the metamorphic event. Data integration of U-Pb on monazite from this work with previous geochronological results from CGTG rocks and surrounding magmatic units indicate the occurrence of intense granitic magmatism between ~2.10 and 2.08 Ga, followed by a high temperature and intermediate pressure metamorphic event. The peak of metamorphism occurred around 2.06-2.04 Ga, and metamorphic cooling between ~2.04 and 1.96 Ga when it reached a temperature below 300°C, indicated by ages 40Ar-39Ar in biotite. These data confirm that high-grade late-orogenic metamorphism evidenced in central Amapá and identified in the Bakhuis Granulitic Belt (Suriname) are coeval. The ages obtained successfully demonstrate the feasibility of carrying out the U-Pb methodology in monazite by LA-ICP-MS at the Pará-Iso Laboratory that can be routinely made available to users.
Acesso aberto (Open Access)
Mineralogia e geoquímica da zona de alteração do depósito de Salobo, Serra dos Carajás
(Universidade Federal do Pará, 1989-07-31) FLORES, Silvia Maria Pereira; OLIVEIRA, Nilson Pinto de
The Salobo 3A copper deposit, located in the Mineral Province of Carajás, State of Pará, is part of a set of sulphide copper occurrences, in a sequence of metasedimentary and matavolcanic rocks, which is more than 70 km long. The product resulting from the alteration, in an equatorial climate, of these mineralized rocks reaches a thickness of 70 to 100 m and presents as a particularity the absence of copper mineralization typical of oxidation zones, preserving, however, approximately, the copper contents of the primary ore. For this research, three profiles were selected for mineralogical and geochemical studies, aiming to identify the Cu support phases, as well as the behavior of some important elements (Ni, Co, Au, Ag. Mo) along the profiles. Mineralogical studies allowed us to conclude that the profiles studied have a low degree of maturity. As a result, it was only possible to characterize horizons in the profiles from the identification of the nature of the clay-minerals present, which were identified as: clay-minerals 15 Å (smectite, vermiculite), 10 Å (illite), 7 Å ( kaolinite) and interstratified (hydrobiotite). The data obtained allow us to conclude that: a) the most important copper support phases are the alteration products of biotites: hydrobiotite and vermiculite. b) Ni, after its release from primary minerals, seems to remain bound to smectite and in some cases to vermiculite, when at depth. Close to the surface or in more mature profiles, Ni seems to be associated with Fe and Mn oxyhydroxides. c) in the destabilization of ferromagnesian minerals, the released Co seems to remain in the profiles, absorbed on the Fe and Mn oxy-hydroxides. d) Au, probably originated from the most magnetic shales, shows to be associated with secondary Fe minerals, and may also be adsorbed in clays, close to the surface. e) Ag may be originally replacing part of the Cu in the chalcopyrite and, in the destabilization of this, it is associated mainly with Mn oxides and Fe hydroxides. f) Mo, originating from molybdenite, must be adsorbed on Fe oxyhydroxides or on clay minerals, requiring more detailed studies for more precise conclusions. Although lateritic enrichment in Cu in Salobo soils was expected, what was observed is that there is only temporary conservation of this element in the intermediate stages of alteration of biotites which, once altered to the point of phyllosilicates 1:1, with the maturation of the profile , will tend to lose this Cu, leached by the percolation waters.
Acesso aberto (Open Access)
Mineralogia e Geoquímica de U, Th, ETR e outros elementos-traço em bauxitas da região de Paragominas, NE do Pará
(Universidade Federal do Pará, 2022-08-17) PARAENSE, Breno Marcelo Ribeiro; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; https://orcid.org/0000-0002-3026-5523
The state of Pará has the largest deposits of metallurgical bauxite in Brazil, with emphasis on the western regions (municipalities of Oriximiná and Juruti, with two mines in operation) and Northeast regions of the state (municipalities of Paragominas – one mine in operation – and Rondon do Pará). The lateritic/bauxitic cover of the bauxite province of Paragominas is a product of extreme weathering of siliciclastic sedimentary rocks and is composed of minerals resulting from the highest degree of alteration, that is, kaolinite (Al2Si2O5 (OH)4), gibbsite (Al(OH) )3 , goethite (FeOOH), hematite (Fe2O3) and anatase (TiO2), to which are added traces of relict quartz, traces of heavily degraded mica and heavy minerals of greater resistance in humid tropical conditions such as rutile (TiO2), tourmaline and zircon (ZrSiO4). In addition to the extraction of bauxite, its mineral transformation, which takes place in the industrial district of Barcarena, near Belém, with the Hydro-Alunorte Alumina refinery, and the production of metallic aluminum by Albras. Due to recent events related to the disposal of waste in decantation basins (DRS) used by the mining company, a climate of distrust on the part of public opinion regarding the safety of the mining populations that live in the vicinity of the company, especially regarding the issue of human health, since the constitution of residues from the mineral transformation of the ore is not completely known. The objective of this research is to determine the presence and study the geochemical behavior of trace elements such as U, Th and ETR, in addition to other heavy metals, such as Hg, Cd and Pb, in bauxites and lateritic covers from the Miltônia mine, in Paragominas, and residues (red muds) from Barcarena, the relationship with the accessory mineralogy of these materials and establishment of reference or background values for environmental assessment. The present work was carried out with samples from 1 bauxite profile (section HIJ-231), located in the Miltônia 3 mine, collected through drilling holes and/or from the mine front, process samples were also collected from the SAG mill of the plant I, separated into different granulometric fractions, supplied by Norsk Hydro. The XRD and XRF analytical processes were carried out at the Mineral Characterization Laboratory (LCM) from UFPA, while the Scanning Electronic Microscopy stage was carried out at the Microanalysis Laboratory of same Unit/Institution. The results of chemical and mineralogical analyzes of samples from the Miltônia 3 mine, both raw bauxite and its granulometric fractions, after autogenous milling, showed a relationship between the high values of ZrO2 and TiO2 verified and the accessory minerals - zircon, rutile and anatase.
Acesso aberto (Open Access)
Níveis de contaminação das águas da bacia do rio Afoya pela aplicação de pesticidas organofosforados e organoclorados no cultivo de algodão - Chinandega, Nicaragua
(Universidade Federal do Pará, 1995-05-25) ALVAREZ CASTILLO, José Antonio; FENZL, Norbert; http://lattes.cnpq.br/6834981018643186