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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)
Adequação de método para avaliação de risco de contaminação ambiental em áreas de estocagem de combustíveis
(Universidade Federal do Pará, 2002-02-28) CHAVES, Cláudio Cezar Cunha de Vasconcelos; CORRÊA, José Augusto Martins; http://lattes.cnpq.br/6527800269860568
Acesso aberto (Open Access)
Adsorção de cromato em materiais sintetizados a partir de rejeito de caulim do rio Capim
(Universidade Federal do Pará, 2008-05-13) MORAES, Milena Carvalho de; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
Industrial and domestic waste cause serious problems for the environment. Industries treatment of kaolin have been deposited reject in large lakes of sedimentation and this has caused accidents as occurred in august/2007 and February/2008. The large volume of kaolin in the lakes sedimentation invaded lakes and rivers from Rio Capim, Para region. This fact resulted in the pollution of waters and death of fish. This problem can be minimized with the use of kaolin reject (KR) in the synthesis of new materials. In this work was used KR treated with organic acid (glycine at concentrations of 5%, 10% and 15% , being obtained the adsorbents: KR-gly-5, KRgly-10 and KL-gly-15, respectively) and mixture NaClO4:HClO4 (proportions 1:50 and 1:75, being obtained the adsorbents KR-NaClO4:HClO4-1:50 and KR- NaClO4:HClO4- 1:75, respectively) and KR as source of Si and Al in the synthesis of zeolites. The materials were characterized by chemical composition and XRD, FTIR, DTA-TG and SEM data. These materials were studied in adsorption process for CrO4 2- from aqueous solutions. The results obtained indicate that the CrO4 2- is adsorbed by kaolin reject and other materials from KR followed this order: KR-gly-10> KR-gly-5>KR-gly-15>KG> KR- NaClO4:HClO4- 1:75> zeolites.
Acesso aberto (Open Access)
Adsorção simultânea de íons níquel, zinco e cobre em sedimentos argilosos da Formação Solimões no estado do Acre
(Universidade Federal do Pará, 2011-09-02) CARDOSO, Vivian Mariana Miranda; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
Torrential rains in the Amazon region provide large leaching of micronutrients, which can be controlled from the adsorption reactions of micronutrients in clay minerals. Studies on the geochemical properties of sediment containing high concentrations of clay minerals in the adsorption reactions of micronutrients is a research topic of great importance considering the proven use of clay minerals with a wide range of applications in various processes and procedures adsorption, involving the remediation of sediment, purification of air and water. In order to make contributions on the physical and chemical properties of soils and applicability of the Solimões Formation from Acre State was carried out a study to simulate natural competitive adsorption of micronutrients cobre, níquel e zinco in different adsorbents sites present in these sediment and to evaluate the influence of the attributes mineralogical, chemical and physico-chemical from these adsorption processes. Preliminary data on the mineralogy of soil samples allowed to select four stations distributed among four named as H1RA, H6B, H23A H9F and located along the BR 364 and BR 317, as well as outcrops in the river Acre. Analyses of samples were performed by XRD (using the powder in the range 2θ=o 5-75 ; analysis of clay fraction in sheets oriented air-dried in an atmosphere of ethylene glycol o and heated at 550 ° C (2θ = 3 -35 ) analysis total chemical by ICP-OES; element analysis exchangeable and available to determine parameters of soil fertility. In adsorption experiments the equilibrium concentrations of cobre, níquel and zinco were determined by AAS. We used the models of Langmuir isotherm, Sips, Toth, Temkin Rendlich-Petersen and the fit of the experimental data of adsorption. The results indicated that the samples present as major minerals quartz and clay minerals of the smectite group, mica and kaolinite mineral and the 14th (H6B) preliminarily identified as interstratified mica-chlorite smectite-mica or chlorite-vermiculite. The other minerals identified in the samples were gypsum (H1RA), microcline (H6B and H9F) and albite (H9F). The average chemical composition is represented by 60.99% SiO2, 15.91% Al2O3, 5.84% of Fe2O3, 2.21% K2O, 0.34% of Na2O, 1.26% MgO, 0.86% CaO and 0.86% TiO2. The following ranges were obtained for the parameters of fertility: pHH2O = 5.24 to 8.36; pHKCl = 3.16 to 7.02; CTCefetiva = 3.37 to 25.42 cmol c / kg;% V (base saturation) = 83.08 to 97.63; saturation% Ca = 4.28 to 69.21; saturation% = 11.32 to 76.42 Mg, K saturation% = 2.32 to 17.32;. In the adsorption experiments were obtained the following ranges for the amount of each element adsorbed (mg / g) in soil samples selected: Cu) from 91.30 to 147.46 in H1RA, 47.25 to 83.93 in H6B , 67.13 to 137.36 in H9F; 73.01 to 141.35 in H23A, Ni) from 49.97 to 93.81 in H1RA; 42.51 to 113.44 in H6B; 62.52 to 134.86 in H9F; 54.13 to 172.58 in H23A, Zn) from 50.11 to 104.50 in H1RA, 44.31 to 64.12 in H6B; 60.21 to 89.91 in H9F; 73.84-135 , 60 in H23A. In these experiments was obtained the following values for the initial pH of the aqueous suspensions of samples in H1RA pHinicial=3.88 to 5.38; in pHinicial H6B = 2.71 to 3.27; H9F in pHinicial = 3.16 to 4, 24 and in pHinicial H23A = 2.61 to 3.29. The values of pH equilibrium were 4.38 to 5.2 in the H1RA sample, 2.71 to 3.16 in H6B; 3.24 to 4.2 in H9F; 2.51 to 3.14.in H23A. It was concluded that the sediment samples analyzed have suitable properties adsorptive for simultaneous retention of Cobre, níquel and zinco in water; the samples with montmorilonite (station H23A) and mineral 14A (H6B) present adsorption of metals transition at pH values between 2.5 and 3.1. The samples H1RA H9F with different groups of clay minerals (smectite, kaolinite and mica) the adsorption of transition metals occurs at pH values between 3.2 to 5.5. The ionic strength increases with decreasing pH . The best isotherm models to describe adsorption processes of Cobre, níquel and zinco in sediment samples were the Langmuir and Sips models. The values of ns Sips indicated that the majority of adsorption systems fall between the homogeneous heterogeneous systems. The equilibrium data and thermodynamic processes of simultaneous interaction between these ions and mineral adsorbents indicated that the processes are favorable, spontaneous and the type of adsorption is specific (chemical adsorption) with the formation of inner sphere complexes.
Acesso aberto (Open Access)
As águas subterrâneas de Belém e adjacências: influência da Formação Pirabas e parâmetros físico-químicos para medidas de qualidade
(Universidade Federal do Pará, 1996-04-08) SAUMA FILHO, Michel; LIMA, Waterloo Napoleão de; http://lattes.cnpq.br/1229104235556506
In the Metropolitan Region of Belém (PA) the water supply to the population comes from springs (physiographic area of Utinga) and from a network of positional tube wells, in general, in more remote urban areas or where pumping is precarious. This work evaluates the groundwater used in the Metropolitan Region of Belém, correlating data of physical, physical-chemical and chemical parameters, in an attempt to compose an understandable picture about the quality of these waters, and to verify the influence that they suffer from the geological units in which they are located. the aquifers that preserve them are located. To carry out the work, water samples were collected in two different seasonal periods: dry and rainy. After exhaustive consultation of the files of companies, institutions and researchers, 17 tubular wells were selected, 9 in Belém, 5 in Icoaraci, 2 in Mosqueiro and 1 in Ananindeua (Annex A). The most frequent turbidity indices were between 9 and 14 units (ppm of SiO2), but some wells showed higher values (33, 41 and 71 ppm of SiO2. Only in some cases, this turbidity can be immediately correlated with the silica content obtained by chemical analysis. The most frequent color measurements are in the range from zero to 7.5 U.C., with the zero index predominating. However, some wells showed a value above 100 U.C. and others, less frequent, with indices varying between 20 and 60 U.C. The pH and electrical conductivity were quite different parameters. Thus, the highest pH and electrical conductivity indices were verified in the aquifers of the Pirabas Formation. In these cases, the pH was around 6 .4 to 7.6 and conductivity between 231 and 362 µS/cm, with a discontinuity at 87.5 µS/cm, also attributed to a well associated with the aforementioned Formation. More acidic waters (pH below 6.38 and above of 4.01) are certainly attributed to the aquifers of the Barreiras and Post-Barreiras Group. The chemical constituents, notably the contents of Ca2+, Mg2+, Na+ and K+, are consistent with the interpretation of the numerical values of pH and electrical conductivity. Without exception, the concentrations of Ca2+ are higher than those of the other cations, establishing a decreasing order according to Ca2+> Mg2+> Na+>K+, with some inversion between Na+ and Mg2+. The highest concentrations of Ca2+ (soon followed by Mg2+) result from the dissolution of carbonates present in the Pirabas limestone. In fact, confirming this assertion, the concentrations of HCO-3 are also much higher than the concentrations of Cl- and SO2-4. It is to be expected, therefore, that the dissolution of Pirabas sediments produces higher concentrations of Ca2+ and HCO-3. The silica and iron contents also discriminate such waters. In general, higher silica contents correspond to greater depths, as would be expected, taking into account the action of chemical weathering on silicate minerals. As for iron, this constitutes a differentiating parameter of the waters of the Pirabas Formation, almost always at much lower levels than the corresponding values associated with the Barreiras and Post-Barreiras aquifers, with, however, exceptions, in which appreciable indices of iron related to Pirabas sediments. It should be noted that the Pirabas Formation appears in the Metropolitan Region of Belém almost always at depths greater than 100 m, although there are records of smaller depths, but these are apparently rarer situations, as is the case with well number 3. , on the University Campus, near the Guamá River, with a depth of 76 m, and the 94 m well of the Museu Paraense Emílio Goeldi, in the central area of the city (Annex A). The exhaustive consultation of the aforementioned archives of institutions, companies and researchers led to the realization that many tubular wells installed in the urban area use water associated with the Barreiras and Post-Barreiras aquifers, where the pH values are almost always, below 6 units, and electrical conductivity measurements rarely reach 100 µS/cm. Finally, it appears that there is a need for greater investments in order to increase the prospection and use of groundwater in the region, as these, in addition to dispensing with treatment prior to distribution, are still a source of resources, not dimensioned, but of great potential.
Acesso aberto (Open Access)
A ametista de Pau d' Arco e Alto Bonito no Pará e a do Alto Uruguai no Rio Grande do Sul
(Universidade Federal do Pará, 1998-03-23) CASSINI, Carlos Tadeu; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
Acesso aberto (Open Access)
Uma análise de cluster via CiteSpace a propósito da espectrometria WDXRF para geocientistas (2001-2021)
(Universidade Federal do Pará, 2023-08-17) CASTANHO, Rebeca Soares; PAZ, Simone Patrícia Aranha da; http://lattes.cnpq.br/5376678084716817
The present bibliometric analysis addresses the use of Wavelength Dispersive X-Ray Fluorescence (WDXRF) spectrometry in geochemical analysis to evaluate scientific trends over a twenty-year period, from 2001 to 2021, using the academic and free bibliometric tool, CiteSpace. For this purpose, 941 international scientific articles involving WDXRF were collected from the Web of Science (WoS) platform using the search terms "wdxrf" or "wavelength dispersive x-ray fluorescence". The data analysis was divided into two parts: the first part aimed to understand and interpret the quantitative aspects of the scientific production related to the technique, while the second part involved a co-occurrence analysis of keywords from the retrieved works. Despite fluctuations, there has been a constant increase in the number of articles related to this spectrometry technique, with 2020 being the year with the highest productivity in the historical series (105 publications). The United States of America leads the country rankings (110 articles); however, the relatively homogeneous distribution of these studies reveals that WDXRF is a widely disseminated technique worldwide. Brazil ranks among the top ten most influential countries in this field, occupying the eighth position with 59 publications. The journal X-Ray Spectrometry, with 82 articles, stands out as the primary venue for the dissemination of research on this analytical technique. In total, 569 keywords were found, connected by 2002 co-occurrence links. The term "trace element" denotes a solidified but always relevant interest in the use of WDXRF for this level of chemical analysis. On the other hand, "nanoparticle" is the keyword with the highest citation explosion over the past two decades, particularly between 2015 and 2021, highlighting a more recent trend in the elemental characterization of nanostructured compounds. The CiteSpace program identified 13 thematic groups, with five being the most notable in the application of this instrumentation: nanomaterial characterization (cluster #0), trace-level heavy metal analysis (cluster #1), chemical speciation (cluster #2), analysis of particulate matter on filters (cluster #5), and provenance of historical ceramics (cluster #6). In summary, it can be concluded that the chemistry of geological materials does not constitute a narrowly defined body of studies concerning WDXRF. Instead, it represents a scientific frontier that expands through interdisciplinary approaches, providing new and integrated methodological approaches to geoscientific research for those who delve into this technique.
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)
Argila de Belterra das coberturas de bauxitas da Amazônia como matéria-prima para a produção de cerâmica vermelha
(Universidade Federal do Pará, 2018-01-10) BARRETO, Igor Alexandre Rocha; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
The Amazon region holds the largest reserves of bauxite in Brazil, whose deposits are covered by a thick bundle of clay material, known as Belterra Clay (ABT). The wide distribution, superficial occurrence, therefore accessible, and clayey ABT nature have aroused the interest of this work in evaluating its technical viability for the production of red ceramics. For the present study, ABT was selected from the large bauxite deposits of Rondon do Pará, samples of the yellow soils from Mosqueiro, illitic clay and gibbsitic clays and one sample of the clayey siltstone. This clay and other materials used as additives were characterized by X-ray Diffraction (XRD), X-Ray Fluorescence (FRX) (CT), Spectrometric Thermal Analysis (TG), Differential Scanning Calorimete (DSC), Inductively Coupled Plasma Spectrometry (ICP-MS), Coupled Plasma Optical Emission Spectrometry (ICP-OES), Scanning Electron Microscopy (SEM) Laser Particle (APL). To determine the physical and mechanical properties, were produce specimens through different mixtures with the samples of Belterra clay and percentages (20, 30 and 40%) of the yellow soil, clayey siltstone, gibbsitic clays and illitic clay. The specimens were calcined at three different temperature moments (900, 1000 and 1200 ° C). Then, linear retraction, water absorption, apparent porosity, apparent density and bending rupture tension were measured. ABT is essentially kaolinite, having quartz, goethite, anatase and gibbsite as accessory minerals. The pure and simple ABT did not present favorable technological aspects for the production of ceramic products, however the same with addition of the yellow soil and clayey silt from the same region significantly improved the technological characteristics of the ABT.
Acesso aberto (Open Access)
Aspectos geoquímicos de gleissolos em pântanos salinos da região Bragantina, Pará
(Universidade Federal do Pará, 2011-06-08) CAMARGO, Paloma Maria Pinto; CORRÊA, José Augusto Martins; http://lattes.cnpq.br/6527800269860568
The knowledge about the nature of depositional processes in the tidal flats, where the salt marsh are included, is very important to understand the tropical coastal ecosystem. Evaporitic minerals, like in Sabkhas, are observed in Bragança salt marsh during the dry season. Halite is deposited on the surface of the soil and gypsum and pyrite precipitate in the subsurface via capillary action out of brines brought up from the water table. The pedogenic processes in the salt marsh where dominate by chemical reactions like halomorphism, hydromorphism, sufate reducing. The aim of this study is characterize the soil of Bragança salt marsh using the textural characteristics, mineralogical and geochemical composition of sediments. The sampling was performed in two transects located in both sides of the PA-458. Each transects have 3 profiles that arise 1 meter depth. The samples were collected by a dutch auger for augering shallow depths (20 cm). The granulometry of sediments was obtained with a laser granulometer and the mineralogical composition was performed by X-ray diffraction techniques. The sand grains were observed using a petrographic microscope with digital image capture. The neoformed minerals and silt+clay grains size were described using a scanning electron microscopy (SEM). In the soil were also studied the pH, electric conductivity, salinity, organic matter content, major, minor and trace elements using classical chemical methods, X-ray fluorescence and atomic absorption spectrometry. Gleysol present in salt marsh show silty-clayey grain size, massive texture, slightly sticky to sticky, very plastic to slightly plastic and friable to compact. Mineralogical it was composed of quartz, kaolinite, illite, smectite, pyrite, jarosite, polyhalite and halite. The pH values ranged from high acidity to acid and the lowest value was found in the depth of 70-90 cm (pH = 3.85), profile P4. Some profiles shown in the Zone 2, where pH is much acid, yellow to orange mottles which corresponds to pyrite oxidation. Based on composition of the adsorption complex of studied soil profiles, the profiles showed high CEC due to the large amount of organic matter and clay minerals. The dominance of Na+ and Mg2+, followed by Ca2+ and K+ assigning to soil eutrophic character. Only the profile P4, B transect, showed dystrophic character. All profiles shown high sodium concentration, characterizing the salt marsh soil as "Solonchak" and therefore may be classified as Salic Sodic Gleysol. The salt marsh soil contains high values of SiO2, Al2O3 and Fe2O3, which reflect its major minerals. Illite, smectite, polyhalite, halite and pyrite are characteristics of salt marsh environment, where the sedimentation occur under the influence of sea water which contributes to Na+, K+, Ca2+, and Mg2+. The presence of jarosite indicates the oxidation of sulfides. The high amount of Na2O reflect the strong evaporation rates under which the salt marsh environment is submitted, and support the neoformation of halite at different depths along a profile. The results and the field observations suggests that the new mineral phases are essentially the result of high evaporation rate, organic matter content, primary mineral phases.
Acesso aberto (Open Access)
Aspectos granulométricos, mineralógicos e químicos de sedimentos de praias (Barras em Pontal) do Rio Acre e sua relação com a fertilidade
(Universidade Federal do Pará, 2004-10-30) VIANA, Érica Cristina Acácio; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
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)
A associação geoquímica Au-As-B-W-Cu-(Sn) em solos, colúvios, crosta laterítica e gossans no alvo Águas Claras-Carajás
(Universidade Federal do Pará, 1997-05-07) COSTA, Newton Cunha da; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
The studied area called Alvo Águas Claras, is located in the Mineral Province of Carajás, southwest of the State of Pará, which represents one of the largest mineral provinces in the world. It is an important area for gold research, which has been prospected since 1991 by DOCEGEO, a subsidiary of Companhia Vale do Rio Doce – CVRD. This target is located in a region of dense rainforest cover, whose geological profiles are highly weathered, showing similarities with the gold deposits described in several other regions of West Africa and Australia. In the Amazon region, the older lateritic profiles are undergoing intense alteration since the end of their formation in the Lower Tertiary, with consequent distribution of these profiles and formation of soils or colluviums. The objective of this work is the detailed study of the behavior of gold, on the surface of this truncated lateritic terrain, and its relationship with trace elements such as B, W, Sn and Cu, in latosols, colluviums and outcropping laterite-gossanic crusts in the area. Thus, a detailed geochemical and mineralogical study of this material was developed, in order to assist in the identification of geochemical signatures indicative of the primary nature of mineralizations and associated rocks, in addition to the evaluation of the dispersion and mobility of these elements during the transformations of the lateritic and gossans crusts. in latosols and colluviums, to establish criteria for geochemical prospecting of these bodies in deeply weathered regions. The work methodology consisted of a field phase, developed on the mineralized bodies denominated by DOCEGEO as Corpo da Anomalia Au/As and Corpo do F-23, with the objective of geological reconnaissance of the area, description of the units and collection of samples of surface. The samples collected were mostly oxisols, colluviums, lateritic crusts, gossans, in addition to host rocks (sandstones and siltstones) and quartz veins. The analytical treatment consisted of several phases such as: drying, quartering and separation of 200g aliquots for pulverizing and 100g for separating heavy and insoluble minerals from pre-selected samples, through the highest levels of boron and gold. Petrographic analyzes were performed using an optical microscope with reflected and transmitted light. All samples were submitted to X-ray diffraction analysis, where both the total sample composition and the different domains of complex samples and isolated minerals were analyzed. A detailed mineralogical study was carried out on tourmalines, involving the calculation and refinement of the unit cell parameters. Quantitative analyzes of the minerals, as well as detailed photographs, were carried out by Scanning Electron Microscopy, with Dispersive Energy System, involving gold particles and other associated heavy minerals. In the geochemical analyses, the following major elements were analyzed: Fe2O3, TiO2, P2O5 through colorimetry; SiO2 and loss on ignition (P.F.) by gravimetry; Al2O3 by titrimetry; Na, Mn, K, Mg by atomic absorption, and some trace elements including Au. In the statistical treatment of data, correlation studies were mainly used, based on Parson's correlation coefficient (r), through binary correlation diagrams, correlation matrices and dendrograms of cluster analysis in R-mode. Isovalue maps were made for Au, B, W, and As, in order to better visualize the surface dispersion of these elements. The geology of the area is characterized by different outcropping and sub-outcropping supergenic materials, which can be juxtaposed in the form of the following composite profile, from top to bottom: Soil horizon (latosol), Colluvium horizon, Lateritic crust and Gossans, the latter being the main gold mineralized bodies prospected in the Águas Claras area. The mineralogy of the entire profile is basically represented by quartz, kaolinite and iron oxides-hydroxides, in different proportions. Accessory minerals such as tourmaline, wolframite, cassiterite and muscovites are frequently found, occurring in varying amounts, practically in all samples. The mineralogical composition found in the various materials analyzed is quite simple in terms of the variety of minerals, but the proportions of the mineralogical phases vary greatly, even within samples from the same horizon. The minerals that represent the greatest distribution among the samples are quartz and hematite. The first occurs abundantly in the oxisol, decreasing significantly in the lateritic crust samples with almost total disappearance in the gossans samples, while the behavior of the hematite is the opposite. The geochemical associations obtained through the multi-elementary analyses: Oxisols: 1) As – Cu – B – Au – W - (Mn) - (Pb); 2) Cr – V – Ga – Mo – Ni – Zn; Colluvium: 1) As – Y – Cu – Mn – Pb – Mo; 2) Au – W – B – F; Lateritic crust: 1) As – W – Au – B – F – Sn; 2) Cu – Ni – Pb – Zn – Sc. The most characteristic geochemical association in all horizons is that represented by Au-B-W-As, possibly with Sn-Cu-F, which must reflect the geochemical signature of the Au-sulfide primary mineralizations, in addition to the influence of the host sediments in addition to the granitic intrusions. Other associations or pairs of correlations involving Cr-V-Ga-Mo-Zn are related to the ease of these elements being incorporated into the structure of iron oxides and hydroxides, abundant in all studied horizons. The gold particles found in the various horizons, have quite varied morphology and purity, which may indicate the presence of several stages of mobilization of this metal in the supergenic environment. As for the trace elements, there are strong anomalies of W, Sn and B, with the minerals responsible for the high levels, respectively, wolframite, cassiterite and tourmaline, the latter belonging to the compositional field of dravita-schorlite, rich in iron , getting very close to the field of ferridravites. Within the above, it can be said that despite the mineralogical simplicity, the concentration of trace elements is quite heterogeneous, but with characteristic signatures that remain in different horizons and that allow delineating the mineralized supergenic bodies and inferring the composition of the primary bodies. The understanding of the dispersion and the characterization of these geochemical signatures prove to be of great importance in geochemical prospecting, in the exploration of other bodies of similar nature in the region.
Acesso aberto (Open Access)
Avaliação ambiental das vias de drenagem da região metropolitana de Belém (PA) quanto à distribuição dos elementos Ca, Cd, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Pb e Zn
(Universidade Federal do Pará, 1991-01-07) MAZZEO, Tereza Elizabete; RAMOS, José Francisco da Fonseca; http://lattes.cnpq.br/8189651755374537
The investigation of the concentrations of heavy metals in the seven main drainage routes of the city of Belém, with a view to the environmental issue, is the central content of this work. The introductory chapters focus on the geology, geomorphology, soils, climate, vegetation and hydrology of the city of Belém, characterizing the natural conditions of the environment in the studied drainages. From the methodological point of view, the work has two phases: the first consists of the recognition, location and determination of metals (Ca, Na, K, Mg, Fe, Cr, Zn, Cu, Cd, Pb, Ni and Mn) and their main sources, natural or anthropogenic, or both; the second, in detailing the distribution and chemical behavior of each metal in the Tucunduba stream, which has a higher concentration of these elements. The Tucunduba stream presents, in addition to the sources of metals common to all other drainages, such as domestic sewage, rainwater discharge and the influence of estuarine tides, the effluent from a leather treatment industry, thus showing anomalous values for the chromium element. The investigation of the physical-chemical parameters of the waters of the drainage ways studied, aims to characterize and identify the behavior of the metallic compounds formed, emphasizing the seasonal variation - function of the rainfall intensity - and the action of the outgoing tides. The Tucunduba stream is the only one to be considered polluted by metals - due to the high concentration of chromium found in its waters and sediments - compared to polluted rivers and lakes in Brazil, Europe and the United States. Despite the small number of samples from each drainage and the great variation in the results, some linear correlations were observed between the concentrations of metals, among themselves and with the physicochemical parameters, which characterize the intense influence of the tides of the Guajará Bay and the Guamá River in the drainages. These correlations also show the existence of large amounts of surfactants derived from synthetic soaps and detergents.
Acesso aberto (Open Access)
Avaliação da influência dos cátions Na+, Ca2+ e Mg2+ na desativação de Ca, Mg-Bentonitas
(Universidade Federal do Pará, 2015-04-28) CARMO, Andre Luiz Vilaça do; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
In Brazil there is no occurrence of sodium bentonite, because of that, companies that explore this mineral raw material using a denominated sodium activation process, which is the exchange of cations in the interlayer space by Na+. Through this process, the bentonite present considerable improvements in their properties rheologies. However, after some time, these properties decline, which has been called deactivation. Thus, the objective of this study was to evaluate the influence of cations Na+, Mg 2+ and Ca2+ in the bentonite deactivation. For this, three bentonite considered calcic, from the state of Paraíba, and a magnesian, coming from the state of Maranhão, were studied in its natural form, activated and washed. The mineralogical phases of the samples were identified by X-ray Diffraction (XRD), chemical composition by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and cations in the interlayer by Cation Exchange Capacity (CEC). The rheological properties’ study was carried out by swelling. The XRD patterns showed that the dioctahedral smectite is the dominant mineral phase. There was the improvement in swelling results of all bentonite after the sodium activation, as well as subsequent decrease in the swelling value over 95 days (deactivation). Only one of the bentonite remained activated. The swelling results of washed bentonite showed increased for approximately the first 35 days, with subsequent decrease. The chemical composition results showed that a small amount of Na+ is removed from the washed bentonite. Furthermore, these results indicate that not only Na+ influences the swelling, but also Ca2+ and Mg2+ cations.
Acesso aberto (Open Access)
Avaliação da poluição por flúor em solos e plantas das redondezas da fábrica de alumínio Albrás, Barcarena-Pa
(Universidade Federal do Pará, 1995-10-31) BENVENUTI, Sara Maria Pinotti; RAMOS, José Francisco da Fonseca; http://lattes.cnpq.br/8189651755374537
The aluminum industry is considered one of the main sources of industrial contamination by fluoride, which generates atmospheric pollution. In this research, a quantitative assessment of the distribution of fluoride in the various environmental compartments in the area of influence of the ALBRÁS/ALUNORTE Industrial Complex, located in the municipality of Barcarena (PA). For this purpose, chemical analyzes of total fluorine were carried out in soils, plants and waters. In the soils, complementary analyzes of Al, Fe, Ca and Mg, determination of pH and mineralogical composition were also carried out. In addition to the data obtained in laboratories, those made available by the ALBRÁS aluminum factory were also used. For the interpretation of the data, geostatistical techniques and visual analysis of isoteor maps were used, which allowed observing the distribution, albeit in a preliminary way, of fluorine levels in soils, groundwater and grasses. It was verified that there is an impact of the industry on the environment, in its area of influence, evidenced by the increase of contents with time and by the “concentric” distribution of the levels of fluoride found.
Acesso aberto (Open Access)
Avaliação da qualidade dos sedimentos de fundo do Rio Murucupi, Barcarena-PA.
(Universidade Federal do Pará, 2011-07-15) REIS, Rafael Melo dos; CORRÊA, José Augusto Martins; http://lattes.cnpq.br/6527800269860568
The development of industrial and urban centres in Barcarena often causes substantial changes in the bodies of water of surrounding areas, primarily in water quality, as a result of inputs of potentially toxic trace elements, as shown the studies of Pereira et. al. (2007), Víglio (2008), Porto (2009) e Pereira (2009). In addition, major environmental accidents has been recorded, mainly related to the disruption and overflow of accumulation dams of industrial waste. In this context, in 2003 and 2009, the river basin Murucupi, wich incudes the urban centres of Vila dos Cabanos and Laranjal, was contaminated by rejects from the beneficiation process bauxite, known as “red mud”. The objetive of this study was to assess preliminarily the bed sediment quality of Murucupi river and distribution of major elements (Al2O3, Fe2O3, TiO2 e Na2O) and trace (Zr, V, Cr, Th, Hf, Ga, La, Sc, Pb, Nb, As, Cd, Cu, Hg, Ni e Zn), enriched in red mud, along the river. For this, triplicate cores were collected with 50 cm deep in bed sediments, in seven ponits along the Murucupí river, in the 5,3 km stretch between the access bridge to the Vila dos Cabanos (M-1 point) and the river mouth (M-7 point). Each sediment core collected in the field was subdivided into five depth intervals in the laboratory: 0-10 cm (A interval), 10-20 cm (B interval), 20-30 cm (C interval), 30-40 cm (D interval) e 40-50 cm (E interval). The triplicate samples from each respective depth interval were then thoroughly homogenised, and later, size, mineralogical and chemical analyses were performed in each sample. The results showed that the sediments are primarily composed of quartz, mica group of minerals, priority muscovite, and albite, in addition to clay – kaolinite, smectite and ilite. The superficial concentrations of the major elements P2O5 and S, and of the trace elements V, Cr, Ga, Pb, Hg and Zn, were higher in M-1 point with a strong decrease toward to mouth, indicating contamination by discharges of urban runoff and domestic sewage from the Vila dos Cabanos and Laranjal. In other hand, the superficial concentrations of S, As and Pb, were high in M-7 point, indicating contributions of these elements from the Arrozal stream, possibily arising from the port of Barcarena and surrounding areas, brought to the mouth of the Murucupi river through tidal movements. The concentrations of these trace elements into beb sediments were much smaller than values measured by Braga (2007) in red mud. This fact is associated to methodological differences used na chemical analysis and to thickness of the sample. However, the statistical correlations performed among Al and Cr, V, Ga and Th, and among Mg, K and Hf, La, Sc and Zr, as well as among Mg, K and the "silt + clay" particle size fraction over the depth, demonstrate that exist a "geochemical signature" of the events of contamination by red mud, recorded in A interval of sediment cores collected in the Murucupi river. The results obtained by the distribution of elements with depth showed that, in general, the major elements Al2O3, MgO and K2O are associated with “silt + clay” particle size fraction, and that the variations in the concentrations of the trace elements, mainly reflect environmental conditions more favorable for mobilization or persistence of these elements over the depth. With regard to the sediments quality, the concentrations mensured for each element were compared with sediment quality indices, known as Sediment Quality Guidelines – SQG, developed by Canada and adopted by Brazil through CONAMA resulution nº 344/2004, and with the indices “consensus-based”, developed by Macdonalds et al. (2000), and also, with reference values of background in the region. Some places, the bed sediments of Murucupi river showed concentrations above ISQG and below PEL for the following elements: 1) Cr in M-1 point, A (38,4 mg.Kg-1) and E (43,1 mg.Kg-1) intervals; 2) Ni in M-6 point, E (18,9 mg.Kg-1) interval, and in point B-1, A (18,6 mg.Kg-1), B (18,3 mg.Kg-1), C (18,4 mg.Kg-1) and E (18,3 mg.Kg-1) intervals; 3) As in M-1 point, C (5,9 mg.Kg-1) interval; and 4) Hg in M-1 point, E (0,199 mg.Kg-1) interval, and in M-2 point, E (0,233 mg.Kg-1) interval. These results indicating that, in these sites, adverses effects to benthic organisms may occur due the high concentrations of Cr, Ni, As and Hg in beb sediments, wich entails additional studies of bioavailability in sediments and toxicity in benthic organisms. Highlights that the elements Pb, Cu, Ni, As, Hg and Zn are enriched over the referece value of regional background at all points sampled in Murucupi river, being that the Cr enrichment also presented in relation to the concentration mensured by Nascimento (2007) in bed sediments of Guamá river. and Pb enrichment only at specific points, related to the hydrodynamics of the river. The results obtained for the Ni raised two hypotheses: 1) in the basins of the Murucupi river and of the reference stream, may exist difusal or eventual sources of contamination for the Ni; or 2) the Ni can be naturally enriched in the region, since the statistical correlations among Mg and Ni in the sediment cores of Murucupi river were good or excellent in nearly all depth intervals. In general, the results obtained showed that the contamination in sediments of Murucupi river is much more associated with difusal sources of pollution, probably from urban runoff and discarges of domestic sewage, than with the environmental accidents involving red mud.
Acesso aberto (Open Access)
Avaliação das características físicas, químicas e mineralógicas da matéria-prima utilizada na indústria de cerâmica vermelha nos municípios de Macapá e Santana-AP
(Universidade Federal do Pará, 2008-09-30) SOUTO, Flávio Augusto França; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
The activity ceramic of the State of Amapá still it presents very incipient, not managing to attend the market local. Among the main hindrances diagnosed, we can cite the next: 1) problems in the rental of lain new; 2) ignorance of the physical, chemical and mineralogical characteristics of the raw material (clay); 3) the lack of technical criteria in the raw material extraction. The work goals are: 1) Do the rising, register and to study clays main occurrences geological context for red pottery of the state of Amapá, the which ones are concentrate in the municipal districts surroundings of Macapá and Santana; 2) In occurrences selected, evaluate the chemical and mineralogical characteristics of the raw material, besides the technological-potteries properties, through which wishes the products improvement of red pottery (bricks and tiles). The work was developed in the area that embraces Macapá's Municipal districts and Santana in Amapá, limited by the latitudes (0º0’30”S and 0º3’30”S) and longitudes (51º12’30”W and 51º5’30”W), where are located the biggest numbers of ceramic of the State. The used materials in this work are coming of clays seized by 4 ceramic: Calandrine (CA) and Amapá Telhas (AT)(Macapá); União (U) and Fortaleza (F) (Santana), besides one regarding Corte de Estrada (CE) in Elesbão's District in Santana's Municipal district, representative sample of the Formation Barreiras. In the total were used 12 samples of the 5 cited places, distributed in profiles with average depth of 2,3 m. The methodology constituted in weigh 1 kg of brute sample, drying itself to 50ºC in stove, disintegrating and homogenizer the same. After this initial treatment, separate in four equal parts, it was separating 500 g for file and the remaining for analysis granulometric. Of the fraction clay it accomplished X-ray diffraction analysis (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TGA), espectroscopy in the region of the infrared with transformed of Fourier (spectrums FTIR), chemical analysis (SiO2, Fe2O3, Al2O3, TiO2, CaO, Na2O, K2O, MgO and loss to the fire). For the technological rehearsals they used rules ABNT and were made bodies of proofs of 6x2x0,5cm to determination of the following parameters: color, water absorption (WA) , apparent porosity (AP), linear shrinkage (LS), apparent density (AD), Flexural Strenght (FS), liquidity limit (LL), plasticity limit (PL) and plasticity index (PI). The data obtained through the chemical analysis show great quantity of SiO2, Al2O3 + H2O, associates to the quartz and kaolinite. Values of Fe2O3, TiO2 suggest refractory and changes reduction in the coloration when burnt to 950ºC, besides being linked to the accessory minerals goethite, anatase and hematite. That was observed CaO and MgO are elements that drop for refractory and linked for montmorollonite and muscovite. Already Na2O and K2O, are fundentes important in vitrification process. For X-ray diffraction, thermal analysis and espectroscopy in the region of the infrared revealed the presence of the following minerals: quartz, illite, kaolinite, esmectite (montmorillonite), goethite, anatase. Clays rehearsed characterize for present elevated plasticity with plasticity index (PI) >15% and fraction silte high percentage. The water absorption measures, apparent porosity, lineal retraction and rupture tension to the inflection after burning in oven in the temperatures of 950ºC and 1050ºC, they presented values adequate for clays use in industry of red pottery. According to the measures obtained in the technological-ceramic rehearsals for the bodies of proofs burnt in the temperatures of 950ºC and 1050ºC, they contacted the next applications in clays studied: 1) Burning temperature to 950ºC - For masonry bricks 10 samples served (U-01, U-02, U-03, F-01, F-02, AT-01, AT-02, CA-01, CA-02, CA-03); for structural bricks 8 samples served (U-01, U-02, U-03, F-01, F-02, AT-02, CA-01, CA-03); and for tiles just 5 samples they presented inside the standards (U-01, U-03, F-02, F-01, AT-02). 2) Burning temperature to 1050ºC - 10 samples they presented inside the standards demanded for tiles production, masonry bricks and structural (U-01, U-02, U-03, F-01, F-02, AT-01, AT-02, CA-01, CA-02, CA-03).
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)
Bauxita, horizonte nodular e cobertura argilosa da região de Paragominas e Juruti, estado do Pará.
(Universidade Federal do Pará, 2011-12-20) CRUZ, Gilberto da Silva; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
The hot and tropical climate during the Cenozoic resulted in the formation mainly lateritebauxite in the Amazon with the frequent occurrence of nodular and/or concretionary horizon consisting of both bauxite and/or ferro-aluminous crusts. The relationship between the nodular and/or concretionary horizon with lateritic profile and origin of the clay cover in the Amazon were the objectives of the present study, so did the selection of two lateritic profiles, located in the region of Paragominas (plateau Jabuti and PA-256 km 17) derived from rocks siliciclastics Ipixuna Formation and/or Itapecuru Group the late Cretaceous, and Juruti generated from the rocks siliciclastics of the Alter do Chão Formation, all in the state of Pará. This study applied the techniques of X-ray diffraction, optical microscopy, scanning electron microscopy and energy dispersive system (SEM/EDS), addition to chemical analysis. The lateritic profiles in the region Paragominas consist from bottom to top: Saprolitic horizon with laminar structures composed mainly of kaolinite beyond quartz grains fractured and corroded; Horizon mottled variegated coloration composed of kaolinite, goethite and hematite; bauxite lilac, look massive, porous, and cut by structures of clay columnar aspect in the plateau Jabuti, while in the PA-256 the bauxite is rosy, columnar and porous; Iron-aluminous crust with nucleous digested or no in the aluminous matrix; Concretionary horizon, consisting of a kaolinitic clay matrix, formed the basis for suesferic ferruginous concretions, porous, zoned, while the top consists particles porcelained aspect that displays a diffuse zoning outline in the outside by white or pink, then a yellow core and a more nucleous red color that sometimes has brown color; Clay cover formed mainly of kaolinite, gibbsitic nodules, quartz grains and fragments scattered laterite. The trace elements show a relationship with iron oxyhidroxides (Pb, V, As e Mo), anatase (Nb, Ta, W, Sn and Sc), zircon (Zr, Hf, Y and U) and gibbsite (Ga), while the rare earth elements exhibit the same behaviour along the profile which indicates a great genetic relationship between the horizons of the profile. The lateritic profile Juruti consists from bottom to top: Mottled horizon variegated color, Bauxite saccharoidal aspect formed by granules of gibbsite and quartz grains fractured and corroded, further bauxite with rounded ferrugious plasm immersed in aluminous matrix generating a feature breccia; Ferruginous crust massive look massive, porous with cavities filled by goethitic cutas and gibbsite, besides the occurrence of quartz grains fractured and corroded; Ferruginous nodules decreasing grain size toward the topo, looks massive porous with cavities filled by goethitic cutas and gibbsite, quartz grains, being immersed in the aluminous matrix of kaolinite; Bauxitic nodules decreasimg grain size toward the top, irregular aspect, porous with cavities filled by gibbsite already in the portion top the nodules are digested by aluminous matrix; Yellowish clay cover with gibbsitic nodules. Since the trace elements in the profile Juruti show concentrations lower than Paragominas and same chemical relationship with iron oxyhidroxides (Pb, V, As e Mo), anatase (Nb, Ta, W, Sn and Sc), zircon (Zr, Hf, Y and U) and gibbsite (Ga), while the rare earth elements occur in the V-shape when normalized to chondrites by enrichment of light rare earth elements (La and Ce) as heavy rareearth elements (Yb and Lu), and marked depression in the range of Nd, Sm, Eu and Gd, and the parallelism of the distribution curves shows that the same genetic relationship between the horizons as Paragominas. The evolutionof lateritic profiles in the two regions are characterized by the following stages: 1 – formation of the crust from the rocks of the Alter do Chão Formation from Juruti, Paragominas derived of the Ipixuna Formation and/or Itapecuru Group; 2 – bauxitization crust; 3 – degradation and partial dismantling of the crust, possibly followed by erosion and deposition for more recessed in the case of PA-256; bauxitization of the nodules and/or concretions and , finally; 5 – formation of Clay cover, called Belterra Clay. The mineralogical and characteristics of the profile studied possibly indicate that these profiles are formed from an evolution in situ for the concretionary and/or horizon and clay cover in relation to lateritic crusts. Periodic climatic variations and tectonic activations are mainly responsible for this evolution.