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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)
Afinidades geoquímicas entre sedimentos (solos) e vegetação (gramíneas e cultivares), além de cabelo de ribeirinhos, ao longo das praias de rios da bacia do Juruá, no estado do Acre e sua importância ambiental
(Universidade Federal do Pará, 2005-06-10) RÊGO, José de Arimatéia Rodrigues do; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
The State of the Acre is located in the southwestern extremity of the Brazilian Amazonia, in an area of 153.149 km2, with a low population density (3,66 inhabitants/km2). The studied area comprehends the basin of the Juruá river between the Feijó and Cruzeiro do Sul cities, including Tarauacá and Rodrigues Alves. In the basin the main rivers are: Juruá, Tarauacá, Envira, Muru and Moa. The same carry in sediments great amounts by traction and suspension from siltic- argillaceous rocks of the Solimões Formation and deposite in beaches formed along the rivers. In drought periods the beaches (point bars) are displayed in its meanders and benefit the riparian that use them to leisure and to short cycle agriculture. The beaches sometimes are used to cultivs of maize (Zea-Mays) and beans (Vigna unguiculata (1) Walp). These beaches also present a vegetation succession of canarana grass (Costus spicatus) and orvalho grass (Brachiaria decumbes). This study evaluates the high fertility of the beaches sediments (soils) and the geochemistry affinity between their sediments and the crops besides riparian hair and the environmental importance of this cycle. So the main rivers that constitute the Juruá basin, enclosing Feijó, Tarauacá, Cruzeiro do Sul and Rodrigues Alves cities were related. Nine stations were established along the rivers and samples of beach sediments, canarana grass leaves, orvalho grass leaves and seeds and beans leaves had been leaves were collected. Besides this, measurement of phisical-chemical parameters of the rivers waters were caried out. Human hair samples were collected in the cities. The sediments samples were analyzed by X-ray difraction (XRD) for mineral determination, are by chemical ICP-MS for characterization (major and trace elements). In attempt to verify the content of Major and Trace Elements, like Ca, Fe, K, Na, Ba, Zn, Mo, Co, Cr, Cu, Pb, Hg, As and Se and their sediment — (solil) — crops transference were camet the chemical compositions analyses were carried out with regal water plus MS-ICP and neutron activation. The studied beaches sediments in the cultivated areas excet the beach of Moa river are essentially fine-grained, ranging from fine sand to silt. And are formed by in decressent order quartz, feldspars clay minerals (smectite, illte and kaolinite) and feldspars. Chemical are constitute binaimes by SiO, (68,0 98,9 % in weight), following by significaty lower values, of Fe>03 (0,13 to 4,37 %), MgO (0,02 to 1,03 %), KO (0,16 to 1,94 %), CaO (0,02 to 1,05 %) and Na,0 (0,02 to 1,03 %) and AlOs, are more concentrated in the sediments of Envira, Tarauacá and Juruá rivers. These values compened chemical with that one of the PAAS and, the Upper Crust, are slightly impoverished in Al, Fe, Mg, K, Ti as well as slightly in Ca and Na, diluted certainly for the high contents of SiO2. In general, the rivers waters of the Juruá basin are dark-colored, as white waters type, due to inorganic material in suspension (suspensates) in high concentration. The criterion of suspensates and phisical-chemical parameters (pH, DO, TDS, temperature, resistivity, electric conductivity and salinity) delimit three geographic zones (sub-basins): a) Envira-Tarauacá, b) Juruá and c) Moa rivers. The first one presents the highest values of all the analyze phisical-chemical parameters, except resistivity, and the area coincides with the more fertile land area State of the Acre. Among the studied vegetables the canarana grass leaves revealed are richerest in K, S, Ca, Mg, P than orvalho grass leaves. Canarana and orvalho grass present chemical similarity in relation to K, P, S, Mg and Ca elements. Only canarana grass, collected in the sediments of the Juruá river tends to become richer in Ca and S. The chemical elements transference sediment (soil)-vegetable presents an absorption for vegetal of the K>P>Ca>P. This order presents the major values for vegetables collected in the sediments of Envira river, emphisizing the importance of Envira river with greater transference potential of macronutrients and being a probable pointer of its superior fertility in relation to the other rivers of Juruá basin. In the sediment-crop-human chain the cycle of Hg shows that in the beach sediments of the Juruá, Envira and Tarauacá rivers the average concentration of Hg (27 ppb) in the sediments below the background range (50 ppb) and in the plants is in according to normal considered range (< 500 ppb) for plants that grow in soils with low contents of Hg; the average contents of Hg in hair in Tarauacá, Cruzeiro do Sul, Rodrigues Alves and Feijó rivers is about 3992 ppb. The lower concentration (average 1680 ppb) was found in Feijó and the higher (6240 ppb) in Cruzeiro do Sul, being normal values and slightly impact indicators, not observed in the region. The slightly anomalous values of Hg in hair is not related to the crops, as well as to the sediments. For hunam other sources of Hg disponibilization must be evaluated as fish or domestic or wild animals meats. The beaches and abrupt declivities (banks) of the white water rivers of the central and western regions of Acre (Juruá basin) are really fertile, adequated to short cycle agriculture and its nutrients and other elements are completely assimilated by vegetables and crops. For the present study the chemistry of the sediments and crops, as well as of human hair, shows that the region does not present geochemistry anomaly of any considerable antropogenic impact.
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)
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 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)
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)
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.
Acesso aberto (Open Access)
Caracterização físico-química da água e mineralógica e geoquímica do material em suspensão e de sedimento de fundo do lago Amapá (Acre)
(Universidade Federal do Pará, 2006-10-27) CARVALHO, Luis Carlos Farias de; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
The Amazon area is characterized by its tropical rainforest and its great fluvial and lacustrine drainage basins. In the Southwest Amazonia, there are at least three great hydrographic basins (Juruá, Purus and Madeira rivers), where the oxbow lakes are very common. The Amapá Lake is on the right margin of Acre River - one of the principal tributaries of the Purus River -, close to the capital of the State of Acre, Rio Branco, as a typical oxbow lake that it was isolated from that river. Physical-chemical parameters measurements of the waters of Amapá Lake were accomplished during dry and rainy seasons in three stations to have an idea of the implications of the seasonal variation on the observed parameters. Samples were collected for elementary chemical analysis of the waters and suspended material, besides mineralogical analyses of the suspensate. Bottom sediments were collected in three survey holes, using a Livingstone-type manual probe, in a dry season, and they were submitted to chemical, mineralogical (XRD and SEM), grain size and geochronologic analyses. The waters of Amapá Lake present high turbid, STS, ammonia, (phosphate) and chloride values that indicate antropic action. The high concentrations of Na, Mg, K, Fe, Al, Mn, Ba and Sr are related to clay minerals (smectite and illite). The sediments of Amapá Lake are silt-clayey fine, distributed in beds (clear and dark), sometimes with organic particulate matter. The mineralogy of the sediments is homogeneous along the three holes and it is mainly represented by quartz, kaolinite, illite and smectite, besides albite and Kfeldspars. The vivianite occurs as pseudomorphs after organic matter debris. They are sediments with acid pH (4-5), unlike the waters, that are alkaline, and with low values of organic matter. The sediments are mainly composed by SiO2, Al2O3 and Fe2O3, besides K2O, MgO, TiO2, CaO, Na2O, P2O5 and MnO. That composition reflects abundance of quartz and clay minerals as illite and smectite. Iron contents are probably represented by amorphous sulphides or by clay minerals (smectite). The chemical results were compared with mean of the terrestrial upper crust and Post-Archean Australian Shales (PAAS). The sediments are impoverished in Na2O, CaO, MgO, K2O and SiO2 in small proportion, and enriched in MnO, TiO2, Fe2O3 and Al2O3. The values of Al2O3, Fe2O3, MnO and TiO2 are similar to the PAAS, being the sediments of the Amapá Lake comparable to those. They are immature sediments related to the clay minerals such illite and smectite and feldspars. Among the trace elements, As and Sb are more enriched in relation to the upper terrestrial crust. They are similar to PAAS. The sediments also resemble those shales via REE's being more enriched in Eu, Gd, Tb and Dy. The suspended sediment is compatible with the Acre River suspensate in mineralogy and chemical composition, partially diverging in the grain size. The Amapá Lake was formed on Early Holocene, at 3160 years BP, presenting average sedimentation rate of 1,1 mm/yr, in colmatation stage, still receiving load in suspension from Acre River, mainly when the inundations occur. The anthropic action centered in fish farmings, deforestations, disordered human expansion, besides an earth highway around the lake, contributes to its colmatation and eutrophication.
Acesso aberto (Open Access)
Caracterização mineralógica e cristaloquímica da prata em sulfetos e sulfossais do centro minero San José (Ouro-Bolívia)
(Universidade Federal do Pará, 1998-03-13) CHOQUE FERNANDEZ, Oscar Jesus; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
Centro Minero San José is located in the Bolivian Tin Belt in a group of hills known as the Serrania de Ouro, which stand alone in the central Altiplano, 8 km from the Eastern Cordillera of the Andes. The Center is made up of polymetallic deposits (Ag, Sn, Pb, Sb, Zn), which at the time of its shutdown in 1990, had a production capacity of 400t/day with average contents of 360 g of Ag/t and 2.0% of Pb, and produced concentrates of 19.10% Pb, 6275 g/t Ag, 12.80% Sb and 2.76 g/t of Au, which could no longer be marketed due to the fine imposed by the presence of Sb. Several metallurgical processes sought to obtain the Ag metal, but due to the complexity of the ore, all of them proved to be unfeasible. There are no references about mineralogical works, especially chemical microcomposition carried out on Ag in this Mining Center, for these reasons this work aimed to study the mineralogical and crystallochemical characteristics of silver in this Center, trying to identify the possible causes of the problems found in the metallurgical processes. Mineralogical studies carried out by reflected light microscopy, x-ray diffraction and scanning electron microscopy, allowed the characterization of galena and franckeite as the carriers of Ag (averages of 0.54 and 0.48% respectively). Stanite-kesterite (average of 0.33%), zinkenite (0.47%), bournonite (average of 0.43%) and sulphosalt types (a) (1.08%), (b) (1.56% ) and (c) (0.43%) are also carriers of Ag, but they occur in small amounts in the ore. Pyrite, arsenopyrite, sphalerite, wurtzite, chalcopyrite, marcasite and pyrrhotite as sulfides, boulangerite and jamesonite as sulphosalts, are associated minerals and do not contain Ag. The crystallochemical studies of galena, franckeite, zinkenite, stannite-kesterite and bournonite suggest the existence of simple ionic substitution of lead by silver in the first three (with influence of Cd, As and Sb contents not detected by SEM-EDS or the occurrence of interstitials) and Ag+=Cu+ in the last two. In galena, there must also be coupled substitution of the Ag++ type (Sb)3+ = 2Pb2+ since the concentrations of Ag are almost similar to those of Sb. The unit cell parameters of galena, franckeite and zinkenite are a (5.933±0.001 Å); a (5.86 Å), b (5.86 Å) and c (17.35 Å), and a (22.111±0.004 Å) and c (4.322±0.001 Å), respectively. Probably the parameter a of galena is influenced by the presence of Ag and Sb in its structure, since it is slightly smaller than that reported in the literature for galenas considered standard (5.936-5.94 Å). The micromorphological characteristics of galena, franckeite, zinkenite and stannite-kesterite, observed in micron scales, show absence of inclusions, suggesting that silver is found as complex solid solutions, being consistent with the ionic substitutions indicated above. Silver is also found in galena as inclusions of franckeite (as needles and straight or curved prismatic aggregates) and zinkenite (needles and polygonal). These inclusions sometimes occur with orthogonal orientation and at other times chaotically, they are even distributed homogeneously and are similar to the topaxial relationships of galena, thus showing strong evidence of exsolution. Irregular-looking stannite inclusions in galena, and bleb-shaped bournonite in stannite, are also due to exsolution. Mineralogical studies also allowed the identification of other problems that may influence the metallurgical treatment of Ag minerals, such as: - Existence of haze or coatings of anglesite and Pb-S-O mineral next to galena and franckeite, which can cause hydrophobic behavior. - Abundance of pyrite in the ore, in addition to a small amount of arsenopyrite, marcasite and exsolved pyrrhotite and other sulfides such as sphalerite, wurtzite and exsolved chalcopyrite, which can cause high consumption of reagents, inhibition of cyanidation processes, in addition to being difficult to removal in refinement. - Presence of Sb and Sb, Cd and As minerals. Next to franckeite, zinkenite and bournonite, boulangerite and jamesonite are the main minerals of Sb. Antimony is also found in the structure of galena, stannite-kesterite, pyrite, arsenopyrite and sulphosalt types (a), (b) and (c). Cadmium is usually present in galena and spharelite sulfides as well as in all identified sulfosalts. Arsenic is restricted to galena, pyrite, franckeite, boulangerite and sulfosalt complex type (a). Sb minerals and these other metals are harmful to different metallurgical processes. The cyanidation of Ag with these metals would be practically impossible and in pyrometallurgical processes they can cause problems of partial melting of the charge and capping the furnaces. In both cases they can form toxic gases. From the point of view of grain release, all minerals carrying or not carrying Ag are considered easy to release, with the exception of the exsolved and myrmekitic phases considered difficult or practically impossible to release. All these aspects allow us to conclude that: - There is a large number of mineral species identified in the ore at Centro Minero San José. Among these species, sulfides and sulfosalts represent the main source of Ag, Sb, Sn and Pb. - Ag is found as solid solutions in galena, franckeite, zirkenite and stannite-kesterite, thus being chemical locking or solid solution locking. Ag solubility limits in these solid solutions are approximately 0.5%. - Ag is also found as exsolutions of franckeite, zirkenite and stannite-kesterite in galena, and of bournonite in stannite-kesterite. - Ag extraction must be done from galena and franckeite minerals mainly, and its treatment must be like base metal minerals. - Non-Ag-bearing minerals can make Ag metallurgical treatment processes more difficult and expensive.
Acesso aberto (Open Access)
Contrastes químicos, mineralógicos e de fertilidade entre solos tipo terra preta arqueológica: sítio da Mata, no limite Oriental da Amazônia, e sítio Porto de Santarém, no Baixo Amazonas
(Universidade Federal do Pará, 2012-06-18) SILVA, Uibirá Sena; KERN, Dirse Clara; http://lattes.cnpq.br/8351785832221386; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
Dark Earth sites are usually found in Amazonian Region. They stand out for their great content of ceramic fragments, urns, and lithic artifacts. Their soils present higher fertility if compared with the neighboring soils. Amazonian Dark Earths origins are related to pre-historic human activity of people who lived in ancient settlements in Amazonian Region for long periods of time. Recent researches reveal that the ceramic fragments from those sites present fertility as high as the soils, and even higher; and for that reason, when the ceramics fragments are exposed to weathering conditions, they could constitute in a potential source of nutrients for the soils that surround them. This study investigated the properties of soils and ceramic fragments from two ABE sites in distinct regions within the Amazon: Sítio da Mata, in São Luís City, Estate of Maranhão, region of forest-savanna transition; and Sítio Porto de Santarém, at the Tapajós River’s outfall, a former rain forest area that is currently intensively urbanized. This research aimed to characterize and compare the material from both sites, and correlate them to de different geomorphologic contexts in which they’re inserted. In the Sítio da Mata was sampled material from the ABE soil profile and from adjacent soil profile, and in Sítio Porto de Santarém, was sampled material only in the ABE soil profile. The samples comprised both soil and ceramic fragments matrices. The material was subjected to particle size analysis (soil samples only), X-Ray Diffraction (XRD) analysis, total chemical analysis by ICP-MS/OES, and fertility parameters analysis. Phosphorus fractionation was also performed in aim to determine the phosphorus species (P-Ca, P-Fe-Al, and organic P) present in soils and ceramic fragments samples. This study investigated the properties of soils and ceramic fragments from two ABE sites in distinct regions within the Amazon: Sítio da Mata, in São Luís City, Estate of Maranhão, region of forest-savanna transition; and Sítio Porto de Santarém, at the Tapajós River’s outfall, a former rain forest area that is currently intensively urbanized. This research aimed to characterize and compare the material from both sites, and correlate them to de different geomorphologic contexts in which they’re inserted. In the Sítio da Mata was sampled material from the ABE soil profile and from adjacent soil profile, and in Sítio Porto de Santarém, was sampled material only in the ABE soil profile. The samples comprised both soil and ceramic fragments matrices. The material was submitted to particle size analysis (soil samples only), X-Ray Diffraction (XRD) analysis, total chemical analysis by ICP-MS/OES, and fertility parameters analysis. Phosphorus fractionation was also performed in aim to determine the phosphorus species (P-Ca, P-Fe-Al, and organic P) present in soils and ceramic fragments samples. ABE from both sites showed high contents of the sand fraction, and soil texture varied from silty-loam to loam sand in Sítio da Mata and sandyloam in the entire ABE profile in Sítio Porto de Santarém. Mineralogical composition in both soils showed no significant differences: they consist most of quartz and kaolinite as primary mineral phases, and anatase and muscovite as accessory mineral phases. Chemical analysis reveal that the soils are composed most for SiO2 and Al2O3, confirming the mineralogical results, and Fe2O3 and TiO2 in minor quantities. P2O5, CaO, K2O and MgO are present in amounts below 0,5%, however, they show higher values in the soils from Sítio Porto de Santarém if compared to Sítio da Mata. Among the trace elements analyzed, only V, Cu, Zn, Sr and Ba stand out, and also show higher values in Sítio Porto de Santarém’s soils. Amounts and distribution patterns for Rare Earth Elements (REE), when normalized by condrits, are similar in both sites, showing enrichment of Light REE, strong positive anomaly for Ce, and negative anomaly for Eu. Differences only in the available P, Ca2+ and Mg2+ contents, although in relatively low values, suggest different anthropic influence over the pre-ABE soils. ABE soils from Sítio Porto de Santarém show higher fertility given for the higher contents of available P, ranging from 72,9 to 305,7 mg Kg-1, and Ca2+, ranging from 3,52 to 5,16 mg Kg-1, compared to 5,4 to 12,7 mg Kg-1 of P content and 0,96 to 2,31 mg Kg-1 of Ca2+ content in Sítio da Mata’s soils. Cation Exchange Capacity (CEC), sum of bases, base saturation and soil organic matter (SOM) were also higher in ABE from Sítio Porto de Santarém. Ceramic fragments from both sites are composed by quartz and metakaolinite, and also illite and anatase. Albite and microcline were detected only in ceramic fragments from Sítio Porto de Santarém. Therefore, they are composed mainly by SiO2 and Al2O3, and in smaller amounts, by Fe2O3 and TiO2. At Santarém, however, ceramic fragments contain also high amounts of P2O5, ranging from 3,49% to 5,37%, and the values for CaO, K2O, Na2O, Cu, Zn, Sr and Ba exceed those from Sítio da Mata. The contents and distribution pattern for REE are similar in ceramic fragments from both sites, with enrichment of LREE, positive anomaly for Ce and negative anomalies for Eu and Ho. Therefore, the ceramic fragments from both sites are mineralogicaly distinct, although they’re immersed in a similar soil matrix. The presence of phosphorus is compatible with others ceramic fragments found in different ABE sites. The fertility of ceramic fragments from Sítio Porto de Santarém showed better rates, with slightly higher pH if compared to ceramic fragments from Sítio da Mata, higher amounts of available Ca2+, K+ and mainly available P, besides higher CEC, sum of bases and base saturation, corroborating the higher fertility of the soils from Sítio Porto de Santarém. Phosphorus fractionation shows that in soil matrix from the studied sites, phosphorus is mainly related to organic compounds, while in ceramic fragments matrix, it is mainly related to nonapatite inorganic compounds. Apatite phosphorus is present in small amounts in both soil and ceramic fragments matrices. Therefore, it is likely that phosphorus present in organic material discarded by ancient people, as various kind of bones, among others, when submitted to tropical pedogenesis, were gradually dissolved, releasing phosphorus, which was partially fixed as Fe-Al phosphates, common mineral phases in tropical soils, as well as organic matter, abundant in ABE, respectively representing the nonapatite inorganic phosphorus and the organic phosphorus fractions.
Acesso aberto (Open Access)
A contribuição da lateritização na formação do Minério de ferro em S11D - Carajás
(Universidade Federal do Pará, 2018-07-24) SILVA, Aline Cristina Sousa da; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
The origin of the soft iron ore hosted in the jaspilites of the Carajás Formation is still subject of debate. In order to contribute to a better understanding of its origin, the SSDFD663 drill hole from the S11D iron mine in Carajás was investigated. Twenty samples were analyzed by XRD, optical microscopy, whole-rock chemistry and SEM/EDS. The profile comprises four weathering horizons, defined from the base to the top, such as protore, saprolite (coarse and fine), and crust. The main ore occurs distributed along the saprolite horizon, it is composed mainly of hematite, and subordinately by magnetite. The amount of quartz increases with the depth, while towards the top increases the amount of Fe-Al(Ti-P)-minerals. The total iron is enriched relatively in the fine saprolite in comparison to the protore (42.55 to 97.62 wt.% Fe2O3). Trace elements such as Zr, Cr, Y, and REE show relative enrichment upward since they usually occur in the presence of residual minerals (such as zircon and anatase). In addition, the REEs exhibit the geochemical signature of the jaspilites, which reaffirms their genetic relationship. A genetical laterite-supergene model is suggested for the origin of soft ore at the S11D deposit.
Acesso aberto (Open Access)
Contribuição dos sedimentos e ictiólitos para a identificação do ambiente de formação do Sambaqui do Moa (Saquarema-RJ)
(Universidade Federal do Pará, 2014-08-28) MACHADO, Sauri Moreira; SILVA, José Francisco Berrêdo Reis da; http://lattes.cnpq.br/1338038101910673; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
The Moa’s shellmound is an archaeological site located in Itaúna, Saquarema coastline from the State of Rio de Janeiro. Three moments of occupation were recognized this site: stratum 3 corresponding to the beginning of the occupation of this site basis; 2, intermediate, points to a more intense occupation with great concentration of mollusks, fish bones and human burials; and 1, the most superficial, related to the last occupation. To identify the environmental conditions of development from Moa’s shellmound, sediment samples and zooarchaeological material were collected in these three strata. The zooarchaeological material is represented by microscopic fish remains (ichthyoliths), composed by microteeth with different morphologies: canines, incisors and molars. The sediments according to XRD analyzes are composed by quartz and kaolinite, calcite, aragonite and fluorapatite. The latter is the main mineral of zooarchaeological material, while calcite and aragonite reflect the remains of shells contained there, abundant in this site. The mineralogical analyses were confirmed by chemical analysis, in which high levels of P2O5, CaO and FB (H2O, CO2), account for the fluorapatite, calcite and aragonite. Chemical modifications variations of the C and P in microteeth suggest that these experienced mineralization, an initial fossilization process, post-deposition. The data of stable isotopes 13C and 15N allowed defining the source of organic matter from Moa’s shellmound as marine/brackish, where the vegetation is represented, predominantly, for C3 plants by type of rainforest. The 87Sr/86Sr ratios in ichthyoliths confirm that the environment surrounding the shellmound as estuary. The tooth morphology allowed us to recognize five families previously not recorded for the site, as Labridae, Serranidae, Ariidae, Erythrinidae and Characidae, which confirm the estuarine environment. The age of the Moa’s shellmound by radiocarbon from the sediments showed disruption of stratum 2, causing a reversal of aged strata which can be explained by processes of formation and/or changes in the rivers changed the geological and geomorphological settings area. Another explanation could be human interference, due to the large number of burials (over 30), has upset the order of the moments of occupation from Moa’s shellmound, and possible erosion. The Moa’s shellmound is therefore installed in an area of marine-estuarine transition.
Acesso aberto (Open Access)
Dispersão mineralógica e geoquímica em crostas e solos lateríticos aplicada à caracterização do substrato do complexo de Maicuru-Pará
(Universidade Federal do Pará, 1991-04-04) ANGÉLICA, Rômulo Simões; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
Maicuru is a typical ultramafic-alkaline-carbonatite complex, located in the NW portion of the state of Pará, intrusive in the granodioritic gneisses of the Guiana craton. Over its rocks, a thick lateritic profile enriched in aluminum and titanium phosphates in the form of anatase has developed. The research rights over the Maicuru area belong to the Docegeo company, which has carried out research work since 1985, involving geochemical prospecting, geological mapping, boreholes, wells, among others. The main objective of the present work was, through the study of the geochemistry and mineralogy of the surface laterites (ferruginous crust and lateritic soils) of Maicuru, to identify the lithological nature of its substrate, in addition to establishing criteria for the geochemical prospecting of these materials under conditions of lateritic weathering under humid tropical forest. The ferruginous crust occupies the central portion of the complex, being differentiated into at least three major units, related to the primary lithology: magnetic crust (with maghemite, ilmenite and anatase), titaniferous crust (with abundant anatase) and phosphate crust, where the aluminum phosphates. The soils border the central structure, with a part derived from the crust itself and another from the primary rocks. The geochemical prospecting carried out by Docegeo consisted of sampling, in a semi-regular mesh of 100 x 200 m, around 1500 surface samples (ferruginous crust and soils), analyzed by this company for the elements Fe203 (total), Ti02, P205 Mn , Ni, Co, Cr, Cu, Pb and Zn. For this thesis, the elements Ba, Ga, Nb, Sc, V, Y and Zr were also analyzed in a second mesh (300 x 400 m), with about 170 samples, and the rare earth elements, in a third mesh , equivalent to half of the samples of the second one. All these data were grouped according to soils and crusts, with the aim of outlining geochemical differences between these two materials, and treated with statistical programs for compatible IBM-PC/XT microcomputers, performing: calculations of basic statistics; analysis of frequency distributions through histograms and cumulative curves, with separation of different populations; construction of correlation matrices and dendrograms of cluster analysis in R-Mode and Q-Mode; estimate of background values and thresholds and construction of surface geochemical maps. Regarding mineralogy, X-ray diffraction studies were carried out on the samples from the 2nd mesh, with the objective of carrying out a semi-quantitative analysis, in addition to studying the dispersion of the main lateritic minerals on the surface. Among the main identified minerals, the following stand out: iron oxy-hydroxides (goethite, hematite, maghemite, ilmenite), titanium (anatasium and ilmenite) and aluminum (gibbsite), which are mainly found in the crusts, in addition to clay- minerals from the kaolinite group, quartz, and aluminum phosphates (especially those from the crandalite group, more frequent in soils). In comparison with other laterites, the crusts and soils of Maicuru have very high average contents of Ti02, P205, Cr, Ba, Sr, Nb, REE and Zr and partly Ga, Sc, Y and V. The ferruginous crusts stand out due to the high levels of Fe 203, Ti02 and P205. Titanium is largely related to anatase (and to a lesser extent to ilmenite) where this mineral derived from titanites and perowskites, characterizing the presence of carbonatites in the Maicuru substrate. Phosphorus, on the other hand, is related to Al-phosphates, characterizing the primary mineralization in apatite, where these minerals are the major carriers of the elements Ba, Sr, Sc, Y and ETR, in addition to Nb and Zr. The soils have higher levels of Al203 and loss on fire, related to clay minerals, gibbsite and Al-phosphates. The anomalous zones obtained for P205 and Ti02 coincided with those delimited by Docegeo, while the background populations of the elements of the 1st grid defined the complex-nesting contact. Other anomalous zones for Nb (which occurs associated with Ti02) and Zr-Ga-Sc were also identified, and although apparently not of greater prospective or economic interest, they showed great significance in the lithological interpretation of the substrate. In addition to these, there were several small anomalous zones in Cu, scattered throughout the crust (especially in the phosphate crust), which may indicate the presence of mineralization in the sub-surface. In the crust, the geochemical associations studied stand out in three large groups, closely related to the three types of ferruginous crusts, where this differentiation is a direct consequence of the lithological variations of the substrate, in which ultramafic-alkaline and carbonatite rocks, partially mineralized, dominate in apatite, titanite and perowskite. Soils, on the other hand, present broader groupings, reflecting a greater process of dispersion through weathering on these three types of crusts and on primary rocks. The geochemical associations studied, especially the two large associations, led by P205 and Fe203, highlight the influence of mineralogy based on iron oxides and hydroxides and Al phosphates, which serve as carriers of the main trace elements that prove the ultramafic- alkaline-carbonatite of the complex. This restriction to P205 and Fe203 shows that Ti02, although present in high levels, does not constitute an expressive geochemical signature. Ferruginous crusts and soils are, in short, from the mineralogical and geochemical point of view, different lateritic materials, and therefore must be treated differently, in terms of geochemical prospecting, as well as the different horizons of a lateritic profile. Prospecting in these lateritic materials, especially in the crusts, should be encouraged – mainly due to their great areal representation in the Amazon – since these can behave like the mimeralized “bedrock” itself, for example, for P, Ti, Fe, Nb, REE and resistatos, in addition to reflecting the lithological nature of the substrate, of great importance in geological mapping.
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Encadeamento geoquímico entre sedimentos (solos) e cultivares em praias, além do cabelo humano de ribeirinhos, ao longo de rios da bacia do Purus, no estado do Acre e a sua importância ambiental
(Universidade Federal do Pará, 2005-06-10) MARTINS, Milta Mariane da Mata; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
The state of Acre is located in southwestern Amazonia and are found two biger important hydrographic basins (Purus and Juruá). The rivers have white water and they show U- shaped valleys in the upper regions and with great floodplains in the lower areas. The water of these rivers is low during the dry season displaying beaches (point bars) and diffs. This situation benefits the population of the region who uses these areas for subsistence agriculture, cultivating mostly maize (Zea mays) and beans (Vigna unguiculata (L) Walp), and complementing the diet with fish and meat of both domestic and wild animals. This work attempts to investigate the high fertility of these beaches and mainly the correlation between the sediments (soils) and crops and between sediments and the riparian (hair samples). The main rivers wich constitute the Purus basin were included in the study as the tonws of Sena Madureira (Iaco and Caeté Rivers), Manuel Urbano (Purus River) and those near Acre river valley (Assis Brazil, Brasiléia, Xapuri, Rio Branco and Porto Acre), where beach sediments, beans leaves and seeds, and maize leaves have been studied in 16 stations. The sediments were analyzed by X-Ray Difraction (X-RD) for mineral identification and by MS-ICP. In attempt to verify the concentrations of elements (major and trace elements) such as Ca, Fe, K, Na, Ba, Zn, Mo, Co, Cr, Cu, Pb, Hg, As and Se and their distribution between sediment (soil) and the crops chemical composition analyses were carried out by “água régia” plus MS-ICP and neutron activation methods. The sediments of the beaches are essentially fine with main mineralogy consisting of quartz, clay minerals (smectite, illite and less frequent kaolinite) and feldspars (K-feldspars and albite). The chemical composition shows high concentrations of SiO2, Al2O3 and Fe2O3, besides K2O, Na2O, CaO. The concentrations found are below of the average of earth’s upper crust (except Si2O), however, they are higher than those of beach sediments, and they are similar to those of high fertility sediments and white water rivers. The chemical results for the crops show that the bean leaves show enrichment in Ca and in K the beans seeds. Ba, Zn, Co and Cr are more concentrated in the leaves than in the bean seeds, while Mo is more concentrated in the seeds. As shows significant concentrations in the crops, especially in bean leaves (average of 338,3 ppb) and this is10 times higher than in the seeds. Mercury does not show variation between bean seed (7,7ppb) and leaf (7,1ppb). Selenium is below the detection limit (20ppb). The maize leaves show enrichment in K (average 1,97%), and Ca (average 0,38%). The correlation between sediments (soil) and crops is analysed by coefficient of biological absorption (CBA) that shows decreasing orders of absorption: for beans leaves (Ca > K > Na > Zn >Ba > Co > Cr > Hg > As); beans seeds (Na > K > Ca > Zn > Co > Hg > As); and maize leaves (K > Ca > Cr > Zn > Cu > Hg > As). The distributions may represent the needs of the crops or even the bioavailability of these elements in the beach environment. The high values of coefficients of biological absorption for these elements in the crops reflect the relatively high values of K, Ca, Mg, Zn, Ba and Cr in the sediments and diffs of the rivers of state of Acre, thus proving their high fertility. The low values of Hg in the sediments (soil) that are also very low in crops and the high values of K, Mg, Ca, Zn and Ba transferred to the crops show the efficiency and strong chemical relation with the soil chemistry. They also show that the beach sediments of staee of Acre do not present geochemistry anomalies of neither natural nor human origin, so we can’t say that there is an environment impact. The high values of Hg found in human hair in Manuel Urbano and in part of Sena Madureira cannot be explained by the consumption of bean seeds and maize. A new source should be investigated as a possibility being the carnivorous or fish diets of population. The present study also confirms the empirical knowledge about the beaches properties for subsistence agriculture that the populations that live near the Acre rivers have known for a long time.
Acesso aberto (Open Access)
Estudos mineralógicos em diamantes, São João do Araguaia, Pará
(Universidade Federal do Pará, 2000-08-29) HÖHN, Helmut; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
Acesso aberto (Open Access)
Estudos mineralógicos, geoquímicos e físicos de caulins em São Miguel da Cachoeira-AM, Manaus-Itacoatiara-AM e BR-010/Rio Capim-PA (Amazônia)
(Universidade Federal do Pará, 1994-07-01) MORAES, Elias Leão; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
Acesso aberto (Open Access)
Evolução mineralógica e geoquímica do perfil laterítico mineralizado a Sn, Zr, Nb, Y e ETR da Serra do Madeira - Pitinga (AM)
(Universidade Federal do Pará, 1991-04-15) HORBE, Adriana Maria Coimbra; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
Acesso aberto (Open Access)
Fertilidade, caracterização química, mineralogia e morfologia de cerâmicas e solos de terra preta arqueológica do Sambaqui Jacarequara (Barcarena-Pa)
(Universidade Federal do Pará, 2015-07-08) REIS, André Heron Carvalho dos; SILVEIRA, Maura Imazio da; http://lattes.cnpq.br/1937795556101203; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
Archaeological Black earth (ABE) are soil stains easily found in archaeological sites. Their dark color and fertility contrasts with adjacent soils, which are usually poor in nutrients. Their formation is related to disposal of organic matter coming from old indian villages, besides the presence of “lítico” artifacts, coal and various ceramic fragments of different styles and traditions. However, researches aimed to evaluate the morfology of the ceramic set, its chemical and mineralogical characteristics and also the assessment of the sambaquis’ fertility still rare. These researches may contribute to a great advance in the knowlegde of ABE and its fertility. In addition, they may elucidate some aspects about the living style of the groups involved. This paper aims to advance in this problematic when analising the ceramic fragments (decorated or not decorated) and the archeo- stratigrafic soil layers (defined by cultural and natural features) from the Sambaqui Jacarequara ABE, in Barcarena, Pará. The samples were submitted to chemical and mineralogical analisis by ICP-MS, ICP-OES, DRX, MEV/EDS, optical microscopy, the assessmente of soil fertility and morfological analises (stylistic and technical aspects) of the sambaqui ceramic set. Regarding to the soils, the obtained data demosntrate and high fertility (V >87 e SB >10), light and strongly basic pH (6,02-8,25), a high concentration of P is avaiable (46,5-818,1 mg/dm3), and the amount of the bases composed predominantly by por Ca e Mg, reflecting the chemical composition of the carbonatic material added. These values are highighted in the layers 2, 3B and 3A with major availability P and Ca, while these values are reduced considerably in the base (Layer 6). The soils are predominantly composed by SiO2, Al2O3, CaO, Fe2O3, K2O e MgO (85, 37 %), which refletcs the mineralogy composed by quartz, calcite, argonite, kaolinite. The concentration of P2O5 is considered low (0, 46 %) when compared with the other ABE in the Amazon, possibly presented in amorphous phase. When confrotating with the crustal avarage is visible the slightly high values of SiO2, CaO, TiO2, P2O5 e MnO. In turn, the ceramics shows basic pH (7, 04-8, 00), high values of sum and base saturation (SB >29, 42; V >94, 7) demosntrating their high fertility level. The P avaiable indicates lower values in the ceramics than in the soil (12-389, 9 mg/dm3 ) displaying the FCs contribution to the soil fertility. Their chemical composition is composed by SiO2, Al2O3, CaO, Fe2O3, K2O, TiO2 P2O5 (75, 33 %). 1 0 Mineralogicaly, the ceramics do not differ from the soil, indicating a local origin to the raw material sources. These ones are composed by quartz phases, musccovite, calcite, argonite, anatase, besides the amorphous phase of metakaolinite, which suggests a burning superior to 550ºC. Crystalline stages related to phosphorus were not found. When confronting chemical data with the ceramics morphology, it is possible to notice that fragments with higher volumetric capacity, fined-grained and lower concentrations of grounded shells in the Clay have a higher concentration of P (> 0,70 %), indicating a possible relation between the materials used during the ceramics fabrication, their use and chemical signature. Morphologically, the results qualified the ceramics in the Regional traditional Mina. However, some variations in the decorative patterns were found between the stratigrafic levels: profile’s basis, one occupation composed by ceramics of introverted forms, fined grained, red engobes e major diversity in the antiplastic use, while from layer 3 there is some ceramics characterized by shells with higher fined-grained, plates with plastic decorations (incised, hand-carved) and fragments much more with the absence od engobe. Therefore, it is concluded that the FCs are fundamental to the maintainance of the fertility of the ABE and also the dissimilarities among chemistry, mineralogy, texture and technology of the ceramics of each layer. It also defines three phases of occupation to the sambaqui: the first phase indicates they would have occupied a promontory of the beach next to the river with the use of aquatics resources in temporary villages; the second one demonstrates a permanent use of the area and intense fishing activity with disposal of organic matter in the soils resulting in the ABE; while the last one demonstrates a post sambaqui occupation with fewer dependence of aquatic resources.
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Fósseis de vegetais da Formação Pedra de Fogo:: aspectos taxonômicos, mineralogia e composição química
(Universidade Federal do Pará, 2000-08-11) MARTINS, Rosiney Araújo; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
In the surroundings of Bielândia-TO, the Pedra de Fogo Formation (Upper Permian of the Parnaíba Basin) fossilized plants were collected, associated with a sedimentary succession, consisting of basal sandstone, overlaid by siltstones and claystone at the top, with nodules and levels flint continuums along its entire length. Morpho-anatomical studies, based on the identification of the type of vascular system (stele) preserved, of 17 specimens of fossilized plants revealed the presence of 9 stems, 4 roots and 2 petioles, and 2 specimens were not identified due to few anatomical elements. preserved. In general, the vascular system of the stems consists of masses of vascular bundles (xylem), limited by a reinforcing parenchyma wall, immersed in a fundamental parenchyma matrix. Traces of phloem were observed. Externally, it is surrounded by a layer of adventitious roots, constituted by vascular bundles immersed in fundamental parenchyma. This configuration is characteristic of the Psaroniaceae family, represented in this work by the genera Psaronius and Tietea, whose stele morphology allowed the identification of the species Psaronius brasiliensis and Tietea singularis. The roots exhibited a protostele-like stele and the petiole showed incipient structuring in the form of concentric rings. Only 1 specimen represented the Taxaceae family, due to the presence of sclereids and tracheids. Studies of 34 thin sheets, representative of transversal and longitudinal cuts to the preserved structure of the plant, showed the presence of granular and prismatic crystalline quartz, together with microcrystalline quartz, with emphasis on the chalcedony variety, both fibroradial and in fringes. In XRD, analyzes of 17 total samples and 17 isolated fractions of the identified tissues, the diffractograms drew the quartz pattern and small reflections of anatase, calcite and hematite. In the infrared spectra these samples recorded diagnostic bands of quartz (1166, 1082, 798, 800, 694, 511 and 462 cm-1) and strictly bands of organic matter (close to 3000 cm-1) and also the doublet 3700 and 3622 cm-1, along with bands 1103, 1035, 1011 and 915 cm-1 characteristic of disordered kaolinite. Quartz crystallinity is medium and low, with values close to 5.0 (calculated index, by XRD, according to Murata & Norman, 1976). SEM images reveal two distinct phases: one rich in microcavities, typical of parenchyma and parenchyma cell contacts, and another more massive, predominant in vessels and fundamental parenchyma. Electron microprobe analyzes show practically pure silica composition (99.73% SiO2) at values of 76.37% SiO2. The highest values of the main impurities were: Al2O3=5.95%; Fe2O3=2.45%; CaO=0.22%; Na2O=0.19 % and TiO2=1.52 % and are coincident with sclerenchyma samples, where kaolinite and hematite appear more frequently. The identified plants characterize a Permian flora, typical of swamps, where environmental changes, which made the pH more alkaline, promoted the death of the forest together with the permineralization of silica in the plant tissues, allowing the preservation of minute histological details. The presence of organic matter, related to methyl and methylene, also confirmed the origin of the process as infiltration and impregnation, developed at relatively low temperatures (below 200° C).
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Geologia e mineralogia do diamante do Garimpo Painin, Itaituba (PA)
(Universidade Federal do Pará, 2000-07-20) BRITO, Marcus Antônio Girão de; CHAVES, Mário Luiz de Sá Carneiro; http://lattes.cnpq.br/7243858021350862; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
Acesso aberto (Open Access)
Geologia, mineralogia e geoquímica do perfil lateritobauxítico da lavra piloto Décio (Rondon do Pará)
(Universidade Federal do Pará, 2017-03-24) SANTOS, Pabllo Henrique Costa dos; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
During the Eocene-Oligocene, extensive lateritic coverings were formed in the Amazon. In this context, the sedimentary sequences of the Parnaíba and the Amazon Basins were lateritized and generated four world-class bauxite deposits: Juruti, Trombetas, Paragominas and Rondon do Pará. The latter is the new bauxite exploration frontier of the Amazon and the Décio pilot mine was developed in it, which presents a 3 m thick laterite-bauxite profile, which extends laterally through vast plateaus with about 350 m of altitude. This work sought to deepen the study of bauxite and its relationships with lateritic landscape in the Amazon region. In the field, five lithological profiles were described in the Décio pilot mine. Then, 42 samples were collected for laboratory analysis involving mineralogical characterization (X-ray diffraction); textural (Optical Microscopy and Scanning Electronics); and chemical (Optical Emission Spectrometry and Mass Spectrometry with Inductively Coupled Plasma). The most probable precursor rocks are the clay facies of the Itapecuru Formation. These would have evolved to a bauxitic clay horizon and then to massive microcrystalline and microporous red bauxite. Bauxite, on the other hand, converges to spherolytic iron-rich crust, rich in iron oxide and partially dismantled. This set is covered by a horizon of ferroaluminous spherolites and a nodular bauxite horizon. The whole set is covered by unconsolidated yellow to red clay, equivalent to the Belterra Clay. The minerals that resisted laterite weathering were zircon, tourmaline, rutile, kyanite and quartz. The neoformed were hematite, goethite, gibbsite, part of the kaolinite, besides the anatase. The main chemical constituents are Al2O3, Fe2O3, SiO2 and TiO2, which together make up more than 99.5% of the profile. Its distribution suggests that the lateritic evolution developed in situ occurred until the formation of the spherolithic horizon. The TiO2 content is much higher in the bauxitic clay horizon than in the other overlying horizons, which is not common in a lateritic evolution from a single, homogeneous parent rock. In addition, Zr and ETR decrease towards the top of the profile, which would also not be expected. Therefore, although the precursor rocks of the entire profile were sedimentary, there was a compositional contrast between those that generated the bauxitic clay horizon and those that generated the other horizons. In addition, the pattern distribution of trace elements shows that even starting from slightly differentiated parent rocks, almost the entire profile followed a similar pattern of evolution, with the exception of the nodular bauxite horizon that behaves as separate unit. These characteristics differ the lateritic profile of the Décio and Ciríaco pilot mine, located in the same bauxite region, but formed from more homogeneous parent rocks.