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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)
Alteração supergênica das rochas básicas do grupo Grão-Pará: implicações sobre a gênese do depósito de bauxita de N5 - Serra dos Carajás
(Universidade Federal do Pará, 1981-11-19) LEMOS, Vanda Porpino; VILLAS, Raimundo Netuno Nobre; http://lattes.cnpq.br/1406458719432983
The present study deals with the supergene alteration of the basic volcanic rocks of the Grão Pará Group and gathers evidences that support the N5 bauxite deposit (Carajás Sierra) to be an extreme product of this alteration. In the lack of a continuous profile, this hypothesis was tested with a composed profile using the subsurface information available for the contiguous N4 plateau where the whole weathered sequence could be observed. The bauxite-rich and lateritic horizons, only developed in N5, were then assumed to be a part of that sequence and taken as its more superficial levels. The basic volcanic rocks are of precambrian age and were classified as tholeiitic basalts compositionally similar to those of the calc-alkaline suites that occur in modern island ares (TiO2-Zr/P2O5 diagram). The primary mineral assembly is dominantly composed of labradorite and pigeonite-augite and has zircon, ilmenite and opaque minerals as the major accessory phases. Hydrothermal activity caused mineralogical changes in theses rocks producing chlorite, epidote, calcite, sericite, amphibole and quartz. Significant chemical and mineralogical changes were induced by the weathering in these rocks and could be evaluated to depths up to 140 m. The serbidecomposed material showed substantial losses of CaO, Na2O and FeO (this due to partial oxidation to Fe+3) and less important lasses of SiO2, MgO and K2O. In contraposition there was relative enrichment of Fe2O3, Al2O3, TiO2 and P2O5 besides major gains of H2O. This new chemical environment favored the formation of compatible stable phases represented, in order of abundance, by chlorite, smectite-chlorite, opaque minerals and quartz. The totally decomposed basalts revealed an aimost complete loss of alkalls, MgO and CaO, with SiO2 contents dimishing to values of approximately 40% of its initial quantities. This enhanced great relative gains of Fe2O3, Al2O3, TiO2 and P2O5 and H2O with respect to the previous alterations stage. The resulting mineral assembly turned out be dominated by kaolinite, goethite and titanium oxides, and secondarily by gibbsite and quartz. Determinations of Cr, Ni, Co and Zr were done for both the bas.alts and its weathered equivalents. Enrichment factors of the order of 1.5 to 5.0 generally progressive towards the surface indicate the greater or lesser mobility of these elements within the supergene environment. Cr, Ni and Co were retained by coprecitpitation with iron hidroxides while Zr was accounted for by the preservation of zircon as a residual mineral. The N5 bauxite deposit consists of a gibbsite-rich upper layer with an average thickness of 4.7 m and average chemical composition of 3-.13% SiO2, 2.3% TiO2, 47.0% Al2O3, 23.0% Fe2O3 and 24.0% volatiles. Mineralogically it is composed of gibbsite, kaolinite, titanium oxides and iron hidroxides (goethite). The subjacent layers show distinct chemical constitution but the mineral suites differ in the proportions rather than in the kinds of the phases present. Downwards it is observed 1) a lateritic crust as thick as 10 m, 2) a gibbsite-rich clay that do not exceed 35 m in thickness and 3) an argillaceous horizon of indefinite thickness. The lateritic crust has an average chemical composition of 3.6% SiO2, 2.0% TiO2, 28.0% Al2O3, 47.0% Fe2O3 and 19.0% volatiles, and a mineralogy dominated by hematite, kaolinite, iron hidroxides, titanium oxides and subordinate quantities of gibbsite. The gibbsite-rich clay has average proportions of 24.0%, 2.0%, 28.0%, 32.0% and 13.0.% for SiO2, TiO2, Al2O3, Fe2O3 and volatiles respectively while the argillaceous horizon shows average proportions of 47.0%, 1.5%, 20.0%, 22.0% and 7.5% for these same components in that order. The mineral assembly of these two last levels is dominated by kaolinite, gibbsite, titanium oxides and iron hydroxides although hematite appears only in the gibbsite-rich clay while goethite and quartz appear, only ,in, the argillacebus horizon. The identification of heavy minerals in samples of both the decomposed basalt and the bauxite material revealed the same suite consisting of ilmenite, zircon and tourmaline, the latter mineral being found in greater abundances in the bauxite. Boron determinations from samples of the various horizons of both sequentes (N4 and N5) indicated contente that varied from 70 to 100 ppm, justifying /the probable presence of tourmaline even in the rocks from which was not possible to separate heavy minerals. The integration of all these data allowed the interpretation of the N5 bauxite plateau as a residual deposit of the supergene alteration of the volcanic basic rocks of the Grão Pará. Group with basis on 1) the chemical and mineralogical identities between the two sequences, especially the decomposed basalt and the gibbsite-rich clay, 2) the chemical correspondente that suggests the argillaceous horizon to be an intermediate stage of alteration between the semidecomposed and the decomposed basalt, 3) the presence of gibbsite in the decomposed basalt suggesting a stage of evolution which, given enough time and the appropriate conditions, could produce a material progressively rich in alumina and 4) typical trace elements of basic rocks present in relatively high concentrations in the bauxite deposit and, taken the genetic link for granted, showing enrichment or impoverishment factors along a common trend from the unaltered basalt to the bauxite material. Special attention was paid to the lateritic crust that formed underlying the bauxite deposit. It has been interpreted as a result of the relativo mobility of Fe and Pd, under Eh-pH conditions that favored the descending movement of Fe and the fixation of in the upper horizons.
Acesso aberto (Open Access)
Análise mineralógica por difratometria de raios-X e método de análise de agrupamento (cluster analysis) como critério para individualização de horizontes bauxíticos
(Universidade Federal do Pará, 2017-03-08) OLIVEIRA, Kelly Silva; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
The formation of wide profile of alteration like as bauxitic deposits on Amazon during Cenozoic period is resultant of intense intemperism caused by seasonal climate, elevated temperature and humidity that are characteristics this region. The bauxitic Province of Paragominas, localized in the east portion the state Pará and west portion of Maranhão, occupies 50,000 km2 approximately forming the largest group of bauxite of Brazil. This work was used X-ray diffractometry, a technique that requires little analysis time, minimum pretreatment steps and small sample amounts, associated with cluster analysis for identify and group samples of same horizon of bauxitic profile of the mine Miltonia 3, Paragominas-PA. The results obtain were correlated with chemical analysis, frequently used for quality control and processing of bauxites. The samples used in this work and your chemical analysis were made available for company Norsk Hydro. The mineralogical types of ore were initially defined through clusters analysis of the XRD patterns of two sections (HIJ-229 e HIJ-231) from polling mesh, with 23 holes each section, and with 375 samples analyzed in all. Based on peak position and intensity of the pattern XRD was possible discern the bauxitics horizons. Due the mineralogic similarity this horizon, the differences found in this group refer principals proportions of minerals constituents: Gibbsite, kaolinite, goethite, hematite, and, more rarely, quartz and anatase. Thought clusters analyses was possible to separate by group a set of similar samples, besides facilitate the analysis of many samples quickly and with efficient results. It was possible yet observe a good correlation of the clusters with the lithotypes identified by the company Norsk Hydro through the results of the chemical analysis. In this way, the analysis of clusters in diffractograms of samples of aluminum ore can be an efficient tool aiding in the protocols of processing of this material.
Acesso aberto (Open Access)
O arcabouço estrutural da região de Chega-tudo e Cedral, noroeste do Maranhão, com base em sensores geofísicos
(Universidade Federal do Pará, 2002-12-05) RIBEIRO, José Wilson Andrade; ABREU, Francisco de Assis Matos; http://lattes.cnpq.br/9626349043103626; PINHEIRO, Roberto Vizeu Lima; http://lattes.cnpq.br/3251836412904734
The central-northern continental segment of the Brazilian coast, which straddles the boundary between the Pará and Maranhão States, is known in the geological literature as the Gurupi Region. The region is characterized by the presence of two main erosional Precambrian windows which expose small-sized Proterozoic shields in Phanerozoic sedimentary basins. Advances in the understanding of the Precambrian geological history of this area have been limited by the lack and quality of exposures due to the deep weathering profile developed. The use of airborne geophysics proved to be a helpful tool allowing a better definition of some lithological contacts and the shape of major tectonic features. The study area covers part part of the Gurupi Shear Belt, located in one of the Precambrian windows mentioned. This segment of the belt exhibits a variety of sedimentary- and igneous-derived supracrustal rocks in association with plutonic-derived metamorphic rocks. These rocks are structurally organized in three main NW-trending strips which were correlated to the Maracaçumé Complex, Gurupi Group and Tromai Suite. Sheared- and hydrothermally-altered basic and ultrabasic intrusive rocks are often found tectonically interlayered with the Gurupi Group rocks. All the above-mentioned rocks have been metamorphozed under low green-schist to low amphibolite facies conditions and affected by hydrothermal alteration. Diabase dikes crosscut the main Precambrian lithological units along several structural trends. Alluvial deposits along active drainages constitute the youngest lithologic units in the area. The kinematic and geometric analysis of the main tectonic structures observed allows the definition of the area as a shear-belt segment, characterized by steeply-dipping planar structures which are indicative of an oblique left-hand continental collision. The area is also characterized by the presence of a relatively narrow NW-trending highlystrained zone developed along carbonaceous metapelitic lithologic units. This corridor is well defined in the geophysical data and represents an important zone of crustal weakening responsable for most of the deformation partitioning which took place in the area. A secondary NNW-trending shear zone branches off from this main deformation zone and follows the contact of the metapelites with the metavolcaniclastic rocks. The splay caused the detachment of the coarse-grained volcanic rocks from the metapelites. The dominant NW-trending tectonic fabric observed along the exposed rocks of the belt is crosscut by three main sets of fractures well defined by the geophysical surveys, trending N-S, EW and NE-SW. The N-S and E-W fracture sets are associated with drag folds showing sinistral and dextral displacements, respectively. The E-W faults correspond to those previously described by several authors as strike-slip faults. On the scale used, no displacement along the NE-trending fractures could be observed in the geophysical maps, although they control the main river courses in the study area. The NEtrending fractures themselves are not outlined in the magnetic data. In function of this, the available data can not support the idea of some authors who described them as major fault zones related to the the main devolopment of the belt. The N-S fault zones disrupt the NW-trending dominant fabric of the belt exibit left-hand displacements. The N-S, NW-SE and NNW-SSE tectonic fabric present in the region show multiple disruptions, crosscutting one another probably due to several reactivation episodes. The crosscutting relations observed in the geophysical data suggest the N-S fault zones are later in relation to the main NW-trending structures of the belt, although their timings could not be defined with the available data.
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 neotectônicos e ecologia da paisagem em parte da área dos municípios do NE do estado do Pará (Tucurui, Baião, Breu Branco, Goianésia, Moju e Tailândia)
(Universidade Federal do Pará, 2007-10-30) SOUZA, Francileide de Fátima Rocha; BORGES, Maurício da Silva; http://lattes.cnpq.br/1580207189205228
This work inside investigated the aspects of the landscape and geologic and geomorphological evidences of the neotectonic context in the region that understands the Tucurui Cities until Thailand (Pará). In this region the incidence of neotectonics processes was responsible for the generation of structures, sedimentary sequences, standards of draining net (Basin of the Tocantins River) and relief System. For execution of this study had been used Landsat ETM+ images for the digital processing in platform ENVI 4,0, digital Models of rise supplied by the SRTM/NASA and images of radar SAR analysis of the relief, draining and recognition of the lineaments expressives, analogical bases elaboration of cartographic bases in environment ArcGIS 9.1. The Analysis of the relief, in the investigated area, allowed to identify as genetic groups: ) Group of Degradation - Constituted of System of Mountain ranges (Mountain range of the Trucará) with flattened topos of amplitude varying between 253 and 290 meters, System of Mounts with angular topos up to 180 meters and Colinoso System with 0 amplitude varying it enters m (base level) up to 120 meters, which constitute most of the paisagística expression; b) Group of Agradação - Englobando Aluvial Plain Systems and System of Fluvial Terraces. These systems are shown with geometrias whose joints if give through the installation of discontinuities, characterizing morfoestrutural compartimentação. The integration of the data, deriving of the analysis of the relief, as well as the characterization of the anomalies of draining and the discontinuities, allowed to the recognition of "landorfms" elementary schools tectonics associates the beams of guided lineaments the E-W, NW-SE, NE-SW and N-S. The joint enters beams of neotectonics imperfections gives way to define one extensional romboedro to south of the parallel 3030"S. The romboedral structure is defined by the arrangement between beams of guided discontinuities to NW-SE, with symmetrical trend and apparent transtensive nature and guided beams of discontinuities the E-W, to the center of the area, with probable dominant component "strike-slip". This geometry is cut by to complicate structures guided to NE-SW. Three main beams of guided discontinuities the N-S affect the inquiry area, and represent "landforms" elementary schools tectonics with extensional trend. These structures had been interpreted as decurrent of the reactivation of the Cinturão Araguaia. They are organized in an anti-symmetrical structure with dominant diving for East and in the height of the meridian 49038W they seem to have strong bond with the tracing of the Tocantins River and imposes fort has controlled to the quaternary deposits. The draining net adjusts it to these standards of structural tropia readily, which answer for the presence of anomalous feições as arcs and elbows, and for the installation of standards in treliça, with strong asymmetry, some partially interpreted as treliça of imperfection. Morfogênese of the area in appraise, in that it concerns to its tectônics aspects was admitted as tied to the performance of a binary guided dextral the E-W, fruit of the dynamics established for the current phase of drift of the American South Plate for West.
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 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)
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)
Comportamento de metais pesados e nutrientes nos sedimentos de fundo da Baía do Guajará e Baía do Marajó
(Universidade Federal do Pará, 2010-01-28) HOLANDA, Nielton de Souza; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
Human activities influence the physical and chemical characteristics of water, sediments and organisms in aquatic environments located in industrialized areas and high population density. With the increasing use of estuaries as a reservoir for a large amount of waste, coastal and estuarine ecosystems are gradually being subject to significant impacts. The bottom sediments play an important role in the investigation of these impacts since it has the ability to retain chemical species and inorganic. The objective of this research is to study the geochemical behavior of metals in the bottom sediment of the Bay of Guajará, Guama River and the Bay of Marajo. The two regions were chosen for their opposite characteristics: a Guajará Bay Area (1) under strong anthropogenic influence and Marajó Bay Area (2) considered the reference. We collected 83 points in Area 1 and 60 points in Area 2. Determined chemical concentrations of the following metals: Ba, Cr, Cu, Fe, Pb, Ni, V and Zn, and also the levels of nitrogen, carbon, organic matter, total phosphorus and phosphorus bound to organic compounds. Area 1 shows the average content of nitrogen of 0,08 %, mean levels of carbon and organic matter from 1,51 % and 2,60 %, respectively. The concentration of phosphorus and phosphorus bound to organic compounds 307 mg / kg and 126 mg / kg, respectively. The concentration of metals showed the following values: Ba (529 mg / kg), Cr (91 mg / kg), Cu (17 mg / kg) , Fe (6,82 %), Ni (32 mg / kg), Pb (27mg / kg), V (120 mg / kg) and Zn (69 mg / kg). Area 2 shows the average content of organic matter 1.70 % of carbon and nitrogen 0,98 % and 0,08 % respectively. The concentration of phosphorus and phosphorus bound to organic compounds 193 mg / kg and 7 mg / kg, respectively. The concentration of metals showed the following values: Ba (596 mg / kg), Cr (102 mg / kg), Cu (21 mg / kg) , Fe (8,31 %), Ni (40 mg / kg), Pb (28 mg / kg), V (141 mg / kg) and Zn (85 mg / kg). The carbon and phosphorus (0,98 %, 193 mg / kg), respectively found in area 2 were lower than those found in area 1 (0,51 %, 307 mg / kg) and demonstrate the influence of effluents that are released in the estuary Guajarino. In both areas there is the same downward trend in levels: Fe2O3> Ba> V> Cr> Zn> Ni> Pb> Cu. In area 1 were found higher metal alone while in area 2, with the major averages, the distribution is homogeneous, two areas in the metals has a slight tendency to concentrate where there is a higher content of organic matter.
Acesso aberto (Open Access)
Dispersão geoquímica dos elementos Si, Al, Fe, Mn, Na, K, Cu e Zn nos solos e sua aplicação na caracterização de áreas geoquimicamente homogêneas
(Universidade Federal do Pará, 1980-05-13) SILVA, Waldise Rossycléa Lima da; RONCAL, Juan Rolando Zuleta
Variations in the chemical composition of soils are used to characterize sub-areas geochemitally homogenous. The aplication of this methodology in a tropical humid region of accentuated topography constitute the principal objective of the present research. Samples of red latosols (Horizon B) developed over gravite, sandstone and basalt occurring in the Central Granite Region of the Serra dos Carajás, Pará State, Brasil were analized for the elements Si, AL., Fe, 40Mn, Na, K, Cu e Zn, by atomic absorption spectrophotometry. Based on the criterion of similarity in the chemical composition (Cluster Analysis, Factor Analysis) the soils were separeted in to different groups. The geographical distribution of the different groups permit the establishment of a Glose relationship between the different parent lithologies and their corresponding soils.
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)
Distribuição dos elementos Si, Al, Fe, Ca, Mg, Mn, Ti, Cu, K e Na em solos desenvolvidos na região do granito central da Serra dos Carajás - sul do estado do Pará
(Universidade Federal do Pará, 1981-03-13) DAMOUS, Nina Rosa Leal; RONCAL, Juan Rolando Zuleta
The distribution of elements in the weathered pro rocks is effected mainly by climate, geomorphology and parent material. The present study deals with the distribution of Si, Al., Fe, Ca, Mg, Mn, Ti, Cu, K and Na in the weathered products of the Central Gravite at Serra dos Carajas - Para, Brazil, which occurs in an area which is characterized by ondulated relief and humid tropical climate. Samples representing two selected weathering profiles were collected to depths that did not exceed 6 m. The analytical treatment consisted of poten/biometric determinations of pH values, the determination of the chemical and mineralogical compositions of the sand, silt and clay fractions, and the determination of the chemical composition of the oxide fraction. The two profiles reveal an intensa process of feldspar removal from the parent granite and the formation of a sand-clayey lato-soil. In this process quartz has been preserved and clay minerals and aluminium and iron hidroxides have been formed constituting the dominant assemblage of the soil. Ca, Mg, Mn, Na and K from the parental rock were nearly completely leached away to the extent that these elements are only found in small amounts in the remaining feldspars or adsorbed on clay minerals. On the other hand, Ti present principally in resistant minerals, practically maintains its' original concentration. Cu is sligthly enriched in the profiles due to adsorption in the clay minerals. The presence of only very small amounts of feldspar along the profiles shows the great intensity of the weathering process acti.ng on the granitic rocks. The direct transformation of feldspar to clay minerals or aluminium oxides is related to the climatic conditions frainy and dry seasons) prevalent in the area.
Acesso aberto (Open Access)
Elementos traços no caulim do Rio Capim, estado do Pará
(Universidade Federal do Pará, 1977-10) MONTEIRO, Reginaldo Wanghon; SCHWAB, Roland Gottlieb
The parent rock material controls the trace element content of a kaolin. The trace element association of Rio Capim kaolin is examined and utilized to verify the provenance of the deposit. The method of emission spectrographye is used for the analysis and is described in its essential parte, in particular the construction of the work curve and the detection limite of the elements The trace element association of the deposit is compared with the trace element association of other kaolin deposits of known provenance. On the basis of this comparison, it is concluded that the deposit was formed by weatering of a granitic parent rock. These conclusions confirm geologic observations about the deposit and the assemblage of heavy minerals, indicating a paraautochtonic origin.
Acesso aberto (Open Access)
Estudo comparativo dos índices de reflectância da vegetação de manguezal e várzea-de-maré do litoral paraense através de sensoriamento remoto e técnicas espectrofotométricas
(Universidade Federal do Pará, 2009-10-08) SILVA, Jadson Queiroz da; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252; COHEN, Marcelo Cancela Lisboa; http://lattes.cnpq.br/8809787145146228
The present work delimited the main littoral vegetations of the Pará State through the differences in the reflectance levels obtained by Landsat images and in situ by a spectrophotometer. This study indicated that the mangrove leaves present lower values of reflectance than others vegetations, mainly in the visible interval of the electromagnetic spectrum.This may be related to the strong absorption developed by the photosynthesis pigments of the mangrove trees. Among its leaves, the Avicennia presented higher reflectance values than Rhizophora. Besides, the reflectance of mangrove leaves changed between the studied areas, mainly the Rhizophora that in Curuçá presented higher values. This can be associated to the stress conditions found in the Bragança and Mosqueiro, since the environmental changes affects the spectral reflectance of leaves. In the case of the mangrove, adverse salinity conditions may hinder the plants development. The tidal water salinity in Mosqueiro presents low values. This factor allows a wider ecological competition between the mangrove species and others vegetations that together with the sediment type, may produce an increase in the stress to the mangrove. It may justify the low height of the trees, and the relatively high reflectance values. Thus, the relationship between the tree height and spectral values of the Rhizophora and Avicennia indicates an inverse relation. This may be attributed to the development of chlorophyll in the initial periods of vegetation growth that allows a elevated amount of energy reflected in the visible interval until the leaves reach its typical green color with relatively lower reflectance. Based on the reflectance data was possible to elaborate maps with the following vegetation units: mangrove, terra firme vegetation, tidal varzea, transition zones mangrove/varzea and herbaceous field.
Acesso aberto (Open Access)
Estudo da alteração hidrotermal,com ênfase no metamorfismo sódico, de rochas granitóides e máficas da região de Canaã de Carajás, Província Mineral de Carajás
(Universidade Federal do Pará, 2007-06-25) SOUZA, Francisca D'ávila Soares de; VILLAS, Raimundo Netuno Nobre; http://lattes.cnpq.br/1406458719432983
The Sossego and Serra Dourada areas are located in the southern part of Carajas ridge, at the contact zone between the basement rocks (Xingu Complex; ~2.8 Ga) and the Grão Pará Group (2.76 Ga). Serra Dourada lies 15 km east of the Sossego deposit, at the transition strip that bounds the Itacaiúnas block and the Rio Maria granite-greenstone terrane. In the Sossego deposit granitoids, metavolcanic rocks, biotite-rich and mafic rocks were investigated, all of them were hydrothermalized and/or deformed to a greater or lesser extent. In Serra Dourada granitoids, their enclaves and mafic rocks were studied, the former being represented by unaltered, altered and milonitized varieties. The likely protoliths of the apogranitoids and metavolcanic rocks that occur in Sossego were syenogranites/granodiorites and porphyritic quartzodiorite/diorite, respectively, while the mafic altered rocks were derived from microgabros. The porphyroclastic texture of the biotite-rich rocks may be an evidence for their protoliths being, at least in part, the same as those of the metavolcanic rocks. Apogranitoids, metavolcanic and biotite-rich rocks have similar REE patterns, suggesting that they might be comagmatic, although some samples of the biotite-rich rocks show higher La/Yb ratios. Concerning the contents of less mobile elements (Nb and Zr), the metavolcanic and biotite-rich rocks are much more similar. Albitization, scapolitization, amphibolitization, chloritization, biotitization, epidotization and potassic feldspatization were the most important hydrothermal processes that affected those protoliths. Albitization is more common in the apogranitoids and acid metavolcanic rocks, whereas scapolitization is more typical of the biotite-rich and mafic rocks. In the apogranitoids two albite generations (I and II) were identified. The albite I represents crystals with chessboard texture produced by the replacement of potassium feldspar. Albite II is present in monomineralic veinlets which correspond to one of the latest stage of hydrothermal activity. Only albite I occurs in all granitoid varieties. In the mafic rocks two scapolite generations were recognized. One refers to crystals aggregates that replaced the primary plagioclase and the other to fine sinuous veinlets of scapolite+Mg-hornblende that, in these rocks, mark the latest stage of the hydrothermal alteration. In the biotite-rich rocks only scapolite I was identified. The scapolite that occurs in both the mafic and biotite-rich rocks have similar meionite (Me=27-28%) and Cl (3-4%) contents, and were most likely formed by a NaCl-rich fluid, with little influence of the rock composition. This fluid might have also been responsible for the production of albite in all analyzed samples. This albite is purer in the apogranitoids (Ab=98.5-99.3%) and the metavolcanic rocks (Ab=99-99.3%) than in the other rocks. In Serra Dourada area, the granitoids include syenogranites, granodiorite and tonalites as well as enclaves of tonalitic composition. Their mineralogical characteristics and calc-alkaline affinity allow them to be classified as I-type granitoids related to subduction with some influence of extensional regime. Most geochemical data indicate that they are cogenetic and have been produced by fractional crystallization. Albitization, scapolitization and minor biotitization were the most important types of alteration that affected those rocks, the first being restricted to the syenogranites, while the other two types are recorded only in the tonalites. The syenogranites present different degrees of alteration ranging from aposyenogranite without hydrothermal albite to albitite with ~75% of hydrothermal albite. In all granitoids, the hydrothermal albite is purer than the magmatic albite. Mass-balance calculations shows that, in relation to the average composition of syenogranites and for volume factors of 0.8-1.1, the albitites gained Na2O and Cu, and lost K2O, Ba, Rb, Sr and W. The scapolitized rocks resulted from the alteration of tonalites and are mainly characterized by scapolite-rich (up to ~70%) veins/veinlets that cross-cut the rocks. In the moderately altered varieties, the scapolite composition is richer in Na (Me=24%) and Cl (4%) in comparison to that present in veins and in the mylonitized granitoids. Massbalance calculations indicate that the formation of the scapolitized rocks was accompanied by losses of Al2O3, MgO, CaO, Sr and Zr and gains of Fe2O3(t), Na2O, K2O, volatiles, Rb, Ba and Cu. The fluids that caused albitization and scapolitization of the rocks were Na and Cl-rich and, apparently, the albitization of the syenogranites preceded the scapolitization of the tonalites. The scapolite composition seems to have been strongly controlled by the composition of primary plagioclase, as evidenced by its more calcic character in the mafic rocks than in the apotonalites. Estimates of Cl content (1-2%) of rocks from both areas were based on its concentrations in modal scapolite, biotite and amphiboles. The stability of scapolite requires high salinity fluids as those that have been reported in the Sossego deposit. No fluid inclusion data concerning the Na-rich fluids responsible for albitization and scapolitization in the Serra Dourada area are yet available, although the evidences, notably the abundance of scapolite, suggest an evaporitic or similar source.
Acesso aberto (Open Access)
Estudo de inclusões fluidas e química mineral do depósito aurífero do alvo Jerimum de Baixo, campo mineralizado do Cuiú-Cuiú, província aurífera do Tapajós, Pará
(Universidade Federal do Pará, 2018-03-06) OLIVEIRA, Helder Thadeu de; BORGES, Régis Munhoz Krás; http://lattes.cnpq.br/4220176741850416
The Jerimum de Baixo gold target is located in the Cuiú-Cuiú golfield, central region of the Tapajós Gold Province, Amazonian Craton. The target comprises monzogranitic rocks, essentially isotropic, that were weak to strongly hydrothermal and carriers of Fe-rich biotite. Chloritization, sericitization, sulfidation, silicification and carbonatization are the most important types of alteration. The produced chlorite is enriched in Fe of the chamosite type and was formed mainly between 280 and 315°C, whereas the white mica assumes muscovitic compositions. The mineralization is represented by quartz veinlets with low sulfide content (pyrite + pyrrhotite ± chalcopyrite ± galena ± sphalerite) in which gold occurs as free-milling particles and in more fragil and altered zones, usually associated with pyrrhotite. The petrographic and microtermometric study of fluid inclusions hosted in quartz veinlets defined aqueou-carbonic, carbonic and aqueous inclusions. The fluids with CO2 represent the probable mineralizing fluid and were generated by phase separation processes between 280 and 380°C, mainly. Further infiltration and mixing processes are indicated for the later aqueous fluids. Temperatures <400°C and the reduced character of the environment (pyrrhotite compounding the ore) point to H2S as the major ligand in the mineralizing fluid and Au (HS)-2 as the primary gold transporting complex. Phase separation, changes in pH conditions, and fluid/rock interaction were the important mechanisms for Au precipitation, which occurred at the brittle to locally brittle-ductile level of the crust (between 2 and 6 km). In general terms, Jerimum de Baixo presents similarities among the other deposits/targets previously studied in terms of hydrothermal alteration, fluid types and mineralization. The features observed in Jerimum de Baixo do not allow a classificatory framework absolutely adequate to any of the classical metalogenetic typological models. Characteristics such as type and style of hydrothermal alteration, type and low content of sulfides, types of fluids involved, estimated depth for mineralization, metallic association (e.g., S, Bi, Te), together with the good correspondence between the data collected in other deposits/targets in the Cuiú-Cuiú goldfield indicate for the Jerimum de Baixo target a gold deposit with magmatic-hydrothermal affiliation, presenting greater similarity to those deposits classified as belonging to Reduced Intrusion-Related Gold Systems (RIRGS).
Acesso aberto (Open Access)
Estudo dos gêneros dyris e tryonia (mollusca:gastropoda) da formação solimões: inferências paleoambientais e bioestratigráficas
(Universidade Federal do Pará, 2016-10-20) LEITE, Felipe S’thiago Freitas; RAMOS, Maria Inês Feijó; http://lattes.cnpq.br/4546620118003936
The Solimões Formation compresses the Solimões Basin Neogene strata, which owns a wide fossiliferous source. The studies about the fossil fauna of this unit provide important information about the evolution of paleoenvironments and hydrographic systems in West Amazonia during the Neogene. The West Amazonia fossil mollusks have been studied since XIX century and have showed potential for biostratigraphy and paleoenvironmental interpretation studies. However, most of those studies have been made using samples originated from outcrops, which limits the studied time range. Since the 70’s decade the exploration of coal and natural gas in West Amazonia opened possibilities to researches of wider time ranges thought boreholes. In the present study, 93 samples from the borehole 1AS-31-AM were analyzed, throughout 302,05 meters dept. The borehole is located by the edge of the Ituí River, in the Amazonas State. Seven of the studied samples presented gastropods in a big amount and high diversity of genuses, with Dyris and Tryonia, aim of this study, as the most abundant ones. Evolutionary events like radiations and extinctions were observed within these genuses. Some never yet found species of Dyris in Brazilian Amazonia had their paleobiogeographic distribution amplified. The presence of guide species such as Dyris megacarinatus, Dyris romeroi, Dyris renemai, Dyris ariei, Dyris microbispiralis and Tryonia scalarioides scalarioides has allowed to date the interval between 170,80m and 175,00m, where occurs the major concentration of gastropods, as Middle to Late Miocene (Serravalian to Tortonian) and relate it with the biozones of mollusks (MZ7 to MZ12), palinomorphs (Crassoretitriletes and Grimsdalea), and ostracods (Cyprideis caraione, Cyprideis minipunctata, Cyprideis obliquosulcata and Cyprideis cyrtoma) established in previous works. Based on the association of fresh and brackish to seawater genuses, the study area is interpreted as an environment which is conformable with a system of lakes close to lagoons.
Acesso aberto (Open Access)
Estudo físico-químico de hidróxi-fosfatos e minerais associados ocorrentes na Chapada de Pirocaua (MA) e no Morro de Jandiá (PA)
(Universidade Federal do Pará, 1982-12-29) REYMÃO, Maria de Fátima Fernandes; LIMA, Waterloo Napoleão de; http://lattes.cnpq.br/1229104235556506
A lateritic profile rich in alumino-calcic and aluminum hidroxi-phosphates (Pírocaua, MA), and another also rich in alumino-oaloio and containning iron and calcium hidroxi-phosphates (Jandiá, PA) has been investigated in order to elucidate the formation of the secondary minerals and the trace element behaviour during tropical weathering. For such purposes it was decided to use X-ray diffratometry and chemical analysis and it was pointed out the applicability of infrared absorption spectroscopy: and differential thermal analysis for the mineral characterization. In order to relate the geochemical alterations it was included a theoretical thermodynamic study. lnfrared absorption spectroscopy and differential thermal analysis have been demonstrated to be valuables methods for studying minerals. Results are presented which demonstrate the usefullness of these techniques. These studies show that it is now possible to correlate differential hermal analysis and infrared data with that from other techniques (chemical analysis, X-ray diffraction patterns) and that the methods yields valuable supplemental information. Theoretical calculations and the use of thermodynamic data (standard free energie and solubility products) reveal some important conclusions about chemical equilibria, mineral formation, solubility and stability relations.
Acesso aberto (Open Access)
Estudo petrográfico, geocronológico e tipológico de zircão de rochas associadas às do grupo Grão Pará, Serra dos Carajás, Pará
(Universidade Federal do Pará, 2018-10-24) RODRIGUES, Anderson Sérgio Batista; MACAMBIRA, Moacir José Buenano; http://lattes.cnpq.br/8489178778254136
In the Carajás basin, northern Mineral Province of Carajás, sequences of volcanosedimentary rocks with ages between 2.76 and 2.73 Ga make up the Itacaiúnas Supergroup. This supergroup encompasses the Igarapé Salobo (2.76 Ga), Grão Pará (2.76 Ga), Igarapé Bahia (2.74 Ga) and Igarapé Pojuca (2.73 Ga) groups. The proximity of ages and the lithological affinity of these units indicate that possibly these rocks have been formed under the same geological context, being different expressions of the same event. The Grão Pará Group consists of two formations: a thick sequence of volcanic rocks (Parauapebas Formation; 2758 ± 2 Ma, U-Pb in zircon), and jaspilites with iron ore (Carajás Formation). In view of the great difficulty of understanding the geographic and geochronological limits of the Grão Pará Group, it was carried on petrographic, geochronological (Pb-evaporation in zircon) and typological study of zircon crystals from of samples associated with the Carajás and Parauapebas formations. Rocks from the Grão Pará Group, as well as the majority of the archaean rocks of the Carajás basin, are hydrothermally altered in different degrees of intensity, irrespective of their lithological type. However, a great number of primary textural features were preserved and petrographic studies allowed the classification of the igneous rocks into two distinct groups: the basalt of dark gray to greenish coloration, fine granulation, mainly intergranular texture, from the Parauapebas Formation; and gabbro with intergranular texture, subofitic to micrographic intensively hydrothermalized (mainly serecitization) from dikes which cut the whole sequence. For the Serra Sul of the Carajás basin, two samples of saprolite of volcanic rocks interbeded with the iron formation and collected in cores from drill holes, were analyzed in this work. Due to the advanced weathering that affected these samples, a typological study of zircon was used in an attempt to identify the previous rocks, which allowed to classify the lithotypes as monzogranitealkaline granite affinity. Pb-evaporation method on zircon crystals, in two samples of volcanic rock saprolite interspersed with the iron formations belonging to the Carajás Formation indicated, indicated ages of 2745 ± 2 Ma for sample FS11D-161 and 2746 ± 2 Ma for sample FS11D-122, understood as time of crystallization of the analyzed crystals and the formation of volcanic rock which contains them. In addition to the high accuracy of these data, they are in perfect agreement with each other and within the gap established for the Itacaiúnas Supergroup. Moreover, because the dated samples come from rocks interbeded with the iron formation, they can be coeval (lava flow) or xi younger (intrusive), and establish a minimum limit for the deposition age of this formation. On the other hand, the age of the Parauapebas Formation, button of the Grão Pará Group, establishes the maximum age for Carajás Formation as 2759 ± 2 Ma. Therefore, the Carajás Formation was deposited in about 15 million of years, which is coherent for the estimated thickness of 400 m. In addition, the Grão Pará Group is covered by the Igarapé Bahia Group, whose volcanic rocks from the button are 2745 ± 1 million years old, which perfectly coincides with the ages obtained in this work. This age corroborates the the gap proposed for the deposition of the Carajás Formation, that is, a maximum of 15 million years. Additionally, the insignificant age difference proposed here for the Carajás Formation and for the volcanic from the Igarapé Bahia Group suggests that all these rocks are part of a same sequence.