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Teses em Geologia e Geoquímica (Doutorado) - PPGG/IG

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/6341

O Doutorado Acadêmico pertence ao Programa de Pós-Graduação em Geologia e Geoquímica (PPGG) do Instituto de Geociências (IG) da Universidade Federal do Pará (UFPA).

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Acesso aberto (Open Access)
Análise crítica das metodologias gerais de mapeamento geotécnico visando formulação de diretrizes para a cartografia geotécnica no trópico úmido e aplicação na região metropolitana de Belém escala 1:50.000
(Universidade Federal do Pará, 2001-11-09) COSTA, Tony Carlos Dias da; ABREU, Francisco de Assis Matos de; http://lattes.cnpq.br/9626349043103626; GANDOLFI, Nilson; http://lattes.cnpq.br/2605833412394930
This thesis brings within its scope the critical analysis of the main national and international methodologies of geotechnical cartography (IAEG, Australian, French, EESC-USP, IPT, IG-UFRJ and IG-SP), as well as the classification of a set of rules for the elaboration of geotechnical maps and charts in the Brazilian Humid Tropics. It also presents geotechnical mapping at the scale of 1:50 000, of the Metropolitan Region of Belém, in the State of Pará, comprising the municipalities of Belém, Ananindeua and Marituba. The methodology is based on the above-mentioned cartographic (conventions/ rules), and is presented in the form of eleven cartographic items: a documentary map of the Metropolitan Region of Belém, at a scale of 1:50 000; a documentary map of the central area of Belém, at a scale of 1:10 000; a gradient map; a geological map; a map of unconsolidated materials; a soil use map; a map of institutional areas and conservation units; a map of floodplain and mainland areas; a map of zones of permanent protection of water bodies; a chart of the preferential areas for the exploration of natural construction materials; and a chart of the preferential areas for the installation of sanitary landfills.
Acesso aberto (Open Access)
Análise da dinâmica das áreas de manguezal no litoral Norte do Brasil a partir de dados multisensores e hidrossedimentológicos
(Universidade Federal do Pará, 2016-12-16) NASCIMENTO JUNIOR, Wilson da Rocha; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252
The objective of this research is to analyze the dynamics of the mangrove areas in the north coast of Brazil from images of remote orbital sensors and hydrosedimentological data (flow and suspened sediment concentration). We tried to understand the existence of causality between the expansion or retraction of the mangroves with the suspened solid discharge calculated from the data of flow and suspened sediment concentration. The mangroves were mapped, using the object oriented classification technique, in the years 1975, 1996 and 2008 based on data from microwave sensors (RADAM / GEMS, JERS-1, ALOS / PALSAR). The data of fluviometric stations and sediments of the National Water Agency were used to calculate the solid discharge in suspension in the rivers Araguari, Gurupi, Pindaré, Grajaú and Mearim seeking to relate the addition and erosion in the areas of mangrove with the sedimentary load of the rivers that drain On the coast. The flow variations reflect the precipitation in the sub-basins of the analyzed rivers and presented a strong and moderate correlation with the temperature anomalies on the surface of the Pacific Ocean evidencing a relation of the El Niño and La Niña phenomena with the precipitation regimes in the Amazon. The variations of suspended sediment concentration were not related to the fluviometric variation suggesting that the annual mean oscillations are reflections of other phenomena (coverage and land use). The results show that the drainage areas of the sub-basins most impacted by the anthropic action contribute with a higher sediment load to rivers that have a higher concentration of native forest. Native vegetation contributes to containment of soil erosion and exposed soil and pasture areas are more vulnerable to soil erosion. The Gurupi, Pindaré, Grajaú and Mearim Rivers presented solid suspended load higher than or equal to the Araguari River. Analyzing the mangroves in the estuaries we noticed the addition of mangroves along the estuaries of the Gurupi and Mearim rivers (Baia de São Marcos) and the reduction of mangrove areas in the Araguari estuary. The Amazon coastal zone is subject to natural processes of great magnitude, but atrophic activities influence the natural dynamics of the region by implementing unsustainable economic practices.
Acesso aberto (Open Access)
Análise evolutiva da paisagem da serra Tepequém - Roraima e o impacto da atividade antrópica
(Universidade Federal do Pará, 2008-01-23) BESERRA NETA, Luiza Câmara; BORGES, Maurício da Silva; http://lattes.cnpq.br/1580207189205228; 1580207189205228; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; 1639498384851302
The north area of Roraima State presents great diversity of geomorphologic featuresformed by dissected plateaus, limited by intermountain plain and relief with a plateau morphology that it is individualized in the extensive plain areas, e.g., of the mountain Tepequém. Since 1930s this was a site of intense activity of diamond extraction what printed changes in the landscape. The main objective of this study is to understand the dynamics evolution of the landscape of the mountain Tepequém under diamond extraction activity and the reason of its erosion susceptibility, being natural or anthropic. To reach these objectives, a description of profiles of soils and saprolitic rock, as well as lateritic profiles were accomplished. Samples of soils, altered rocks, laterites and coal were collected. Besides, width, depth, extension and directional alignment of the channels of the gullies measurements were carried out. The collected materials were submitted to the following analyses: grain size, by humid way; minerals identification by X-ray diffraction and SEM techniques; total chemistry analysis (major elements) by ICP-MS and content of organic matter, humidity and density of the soil measurements. Coal samples were submitted to radiocarbon analyses by AMS (Accelerator Mass Spectrometry). Appling the interpretation of optical images (Landsat-5/TM and Cbers-2/CCD) and the cartographic base, maps of structural alignment, relief (altimetry and declivity), drainage and vegetation covering were also elaborated. The mountain Tepequém stand out among the landscape dominated by relief of hills, residual hills and plane-slightly wavy surfaces because of its rectangular-rhombic format and outline of steep scarps elaborated on sedimentary rocks of Paleoproterozoic. The drainage system of the area delineates parallel, angle-rectangular and faults standards. The relief and drainage morphology of the mountain Tepequém and its around area define a subordination to the structural arrangement E-W, NE-SW and NW-SE directions represented by normal and strike-slip faults. In the mountain Tepequém, the geomorphologic compartments are established by 575 to 670 m high plain intra-valleys surfaces bordered by less than 774m high hills and residual hills and edge slopes less than 1100m high. The bush grassy savanna dominates this landscape and recovers the edge scarps and extends along the regional plain. The ciliary forest covers small stains along the Cabo Sobral and Paiva rivers. This scenery was quite modified because of diamond extraction activity. However, with the decline of this activity, the ciliary forest recovers spontaneously, as the optical images of the last 22 years shows (1984, 1995 and 2006). Intra-valleys plains were developed on sandy soils constituted by medium and fine grain size sandy domains, sub-angles to sub-rounded poorly selected, with low cohesion and small quantity of organic matter. These soils are developed on saprolitic derived of sandstones and siltstones. Locally stone lines and colluvial are observed, usually on the saprolitic. Immature laterites are found in the center-north hills of the mountain Tepequém. Quartz, muscovite in sub-milimetric plates and kaolinite partially involving the grains of quartz are predominant in soils constitution, while the lateritic profiles are constituted by gibbsite, goethite and hematite, besides quartz and kaolinite. Laterite and quartz fragments constitute the stone lines. High concentrations of SiO2 confirm the essentially quartz-character of the soils, while the values of Al2O3, K2O, MgO, Fe2O3 and TiO2 are more expressive in the saprolitic zones, confirming the kaolinite, muscovite and hematite domain, derived of claystones and siltstones. The radiocarbon ages in coal obtained for the superficial materials (colluvial and stone lines) show that these materials were formed at least 3.822 years BP. The intermountain plains reveal in its landscape erosive features in the piping formations, dolines and gullies, developed in the lands with sandy to silt materials domain. The channels of gullies are mainly aligned in the directions NE-SW and NW-SE corresponding to the directions of fractures and faults that section the Tepequém Formation. The seemingly stabilized gullies are partially covered by ferns that grow on the side and bottom surfaces of the channel. The evolution of the landscape of the mountain of Tepequém specially the formation of its general internal structure involves the tectonic still in Proterozoic. The inherited morphology reflects in the steep scarps around as well as in the top such a great synclinorium. The evolution of the landscape of the mountain of Tepequém during Cenozoic is marked by formation of small hills, some of these protected by lateritic crusts suggesting registration of a humid and hot paleoclimate in Pleistocene, which can admit the installation of the drainage net. The erosive process of the fluvial courses allies with the high gradient favored the transport of part of the sediments to W-SW direction, contributing in the formation of the intermountain plains. The current scenery is marked by the erosive retaking favored by the sandy non-cohesive nature of the soils, ally to a paleorelief inclined to the valleys and strongly fractured and failed that causes a strong shallow surface stormflow propitiating the piping formations, dolines and then the gullies. Thus, the diamond extraction activity can contribute in the intensification of the gullies but, however, it was not the decisive factor. Therefore, the evolution of the landscape of the mountain Tepequém in Proterozoic and in Cenozoic until the present is due to the interaction of multiple processes involving the tectonic history, the weathering changes and the several erosion cycles, as well as the restricted sedimentation and the small anthropic contribution.
Acesso aberto (Open Access)
Aplicação da composição isotópica de multielementos no monitoramento ambiental de área circunvizinha à barragem de rejeito: o caso da mina de cobre da Serra do Sossego, Canaã dos Carajás – PA
(Universidade Federal do Pará, 2017-06-09) OLIVEIRA, Simone Pereira de; MOURA, Candido Augusto Veloso; http://lattes.cnpq.br/1035254156384979
Tailings dams from ore mining activities are relevant compartment for environmental monitoring because the dam can present undesirable forms of water outlets such as infiltration. The present thesis proposed multielement isotope study in order to evaluate the use of the isotopic composition of oxygen, hydrogen, strontium and lead as a tool for the environmental monitoring of groundwater vulnerable to the tailings dam. This research was conducted in the area of the Serra of Sossego copper mine and, in addition to the isotope study, the hydrochemical characterization of groundwater and surface water was caried out. Besides, the direct reading of the isotopic composition of lead (without chemical treatment of the water sample) was applied for the first time, using multicollector inductively coupled plasma mass spectrometry, in the laboratory Para-Iso. The hydrochemical characterization of groundwater in the Serra do Sossego mine area showed that it is moderately acid (pH ~ 6). Only the AP15 and PS32 wells, under the influence of the drainage of the mixed pile (ore waste + sterile), presented high electrical conductivity (599 μS / cm2 and 694 μS / cm2) and the higher sulfate content (1.82 to 6.57 Meq/L). In general, iron (29.7 mg/L), manganese (69.7 mg/L) and copper (24.9 mg/L) present the highest metal content in the groundwter. In terms of the isotope studies, the groundwater of PS17, PS04, AP15 and PS32 wells and the water of the Dam present the least radiogenic lead isotopic composition. The water sampled in the AP15 and PS32 wells would be representative of the lead isotope signature of groundwater in the mine area (206Pb/207Pb = 1.1481 to 1.1663) and, probably, is indicative of the lead isotope composition of the meteroric water. The lead isotope composition of the groundwater of the wells PS04 (206Pb/207Pb = 1.1784-1.1850) and PS17 (206Pb/207Pb = 1.2100 to 1.2160) may indicate a small contribution of the rocks of the region (206Pb/207Pb > 1.6807). In turn, the lead isotope signature of water of the Dam (206Pb/207Pb = 1.2279) suggests, as expected, a slightly more pronounced contribution of the ore and the rocks. On the other hand, the lead isotopes of the water sampled in the wells MNA23 and PS06 show a more radiogenic signature (206Pb/207Pb = 1.6741 to 1.9196), which is similar to those of the chalcopyrite and the diabase of the Sequeirinho open pit, revealing a more significant contribution of the ore and rocks. As the lead isotope composition of water from the dam is different from that of the groundwater, it can be used for the environmental monitoring of the influence of the water from the dam in groundwater in the Serra of Sossego mine area. In those wells with less radiogenic lead isotope signature, a possible contribution of the water from the dam would result in a more radiogenic lead isotope composition in the groundwater. Conversely, in those wells with more radiogenic lead isotope signature, a contribution of the water dam for the groundwater would decrease the values of the measured lead isotope ratios. On the other hand, the application of the sulfur isotopes for environmental monitoring presented some limitation in the study area, due to the lack of contrast of the sulfur isotope composition among the sulfides of the Sossego deposit (δ 34S ~ 2-7 ‰), the water from the dam (δ 34S ~ 2 ‰), and the drainage of the mixed pile (δ 34S ~ 2‰). This prevents the recognition of a possible contribution of the tailings dam to groundwater. Mixing models using the 87Sr/86Sr ratio as a function of the strontium concentration and δ 18O values, also showed some limitations, since there is no contrast between the values of the 87Sr/86Sr ratio of the water from the dam (0. 7458 to 0.7539) and the rocks of the mine area (granite ~ 0.7474). Such similarity, in principle, would not allow identifying the contribution of the water from the dam. However, since groundwater generally exhibits less radiogenic values of the 87Sr/86Sr ratio (0.7161 to 0.7283) and well below the dam values, the strontium isotopic composition can be used for environmental monitoring of groundwater. Hydrogen and oxygen isotope data revealed that, in the rainy season, the groundwater presented values of δ 18O and δ D varying from -2.74 to -7.17‰ and from -15.6 to -46.0‰, respectively. In turn, an enrichment of 18O and D, with values of δ 18O between -1.67 and -7.29 ‰ and of δ D between -0.23 and -46.1 ‰, is observed in the dry season. Hydrogen and oxygen isotope composition of the water from the dam (δ 18O from 1.24 to 2.79 ‰ and δ D from 1.40 to 7.0 ‰) is very different from those of the groundwater and of the drainage of the pile. A mixing model performed with oxygen and hydrogen isotopes showed that these elements are the ones that best respond as indicators of the contribution of the waters from the dam to groundwater. The application of this model revealed no influence of the water from the dam on the groundwater during the period of this study. The results obtained in this multielement isotopic study suggest that the environmental monitoring of the groundwater of the Serra do Sossego mine to investigate the possible contribution of the water from the dam, can be done more efficiently with the oxygen and hydrogen isotopes. The isotopic compositions of lead and strontium can also be used for monitoring the groundwater, but this has to be done more systematically due to the small contrast between the isotopic composition of these elements in the dam water and in the groundwater. Finally, the isotopic composition of sulfur is the one that would contribute least to the environmental monitoring of the groundwater of the study area.
Acesso aberto (Open Access)
A aplicação da cromatografia gasosa acoplada (GC-FID), isótopos estáveis, palinologia e razão C:N na reconstituição paleoambiental de manguezais do Estado da Bahia e Espírito Santo.
(Universidade Federal do Pará, 2024-07-30) SILVA, Fernando Augusto Borges da; ALBERGARIA-BARBOSA, Ana Cecília Rizzatti de; http://lattes.cnpq.br/2666263256585897; FRANÇA, Marlon Carlos; http://lattes.cnpq.br/8225311897488790; https://orcid.org/0000-0002-3784-7702
Mangroves depend on ideal geomorphological, geochemical, and climatic factors to develop. Brazil, with its highly indented coastline under tropical and sub-tropical climate regimes, presents suitable conditions for the establishment of these ecosystems and distribution. The dynamics of these mangroves can be influenced by factors related to climatic variations and changes in hydrodynamic flow, resulting in modifications in sediment input and the origin of organic matter. These changes can be observed throughout the Holocene in different regions in of the country. On the northeast and southeast coast, the evolution of these ecosystems is associated with fluctuations in relative sea level (RSL) and sedimentary dynamics, while in the southern region, the change in the distribution of mangroves is a reflection of fluctuations in the RSL and climate changes caused by warming global. Recent studies seek to describe the evolution of these environments based on the elemental and isotopic characterization of organic matter. These constitute important tools in paleoenvironmental reconstruction. However, it is necessary to remember that the comparative analysis of the largest possible number of independent parameters is relevant as it adds value to the research and increases the reliability of the data to be analyzed, generating more precise information. Therefore, aiming to unravel the dynamics of organic matter in mangrove environments, as well as understanding movements of expansion and/or contraction of these ecosystems, analyzes of nalkanes were carried out using chromatography (GC-FID), associated with the sedimentary study, pollen data, isotopic and elemental analyses, synchronized with 14C and 210Pb dating, which allowed obtaining information about past biogeochemical processes and environmental changes during the Holocene and Anthropocene in the coastal plain at the mouth of the Itapicuru river (BA) and at the mouth of the Barra Seca and Jucu rivers (ES). Thus, the results of this research are presented in five scientific articles. The first, see chapter III, deals with the expansion of mangroves at the mouth of the Itapecuru river (BA) during the Anthropocene. The second scientific article (chapter IV) deals with the dynamics of mangroves at the mouth of the Barra Seca River, on the northern littoral of the State of Espírito Santo. The third article (chapter V) discusses the palynology tool used to understand the dynamics of coastal vegetation.The fourth article (chapter VI) presents the environmental changes that occurred at the mouth of the Jucu River, on the central coast of the State of Espírito Santo. Finally, the fifth article presents the results of n-alkanes analyses, compared with isotopic, elemental, palynological data, and 14C dating on the coastal plain of the Barra Seca River.
Acesso aberto (Open Access)
Aproveitamento dos resíduos cauliníticos das indústrias de beneficiamento de caulim da região amazônica como matéria-prima para fabricação de um material de construção (pozolanas)
(Universidade Federal do Pará, 2007-12-18) BARATA, Márcio Santos; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; https://orcid.org/0000-0002-3026-5523
The Capim and Jarí regions are the most important kaolin district in the Amazon region, with the largest Brazilian reserves of high whiteness kaolin for paper coating products. Kaolin is obtained from three companies (IRCC, PPSA and CADAM) which produce annually around 1,000 M ton kaolinite-rich wastes derived mainly from the centrifugation phase of the process. The sludge is disposed on artificial sedimentary lakes covering large areas. Another type of kaolin waste is related to a non-processed iron-rich hard or flint kaolin, that overlays the so-called soft kaolin horizon (the main ore). These wastes exhibit appropriate characteristics for the production of high-reactivity metakaolin because they are extremely fine and composed of mainly by kaolinite. The main purpose of this work is to evaluate the feasibility of using these wastes as raw materials to produce mineral admixtures for OPC concretes. The wastes were firstly characterized for x-rays diffraction, thermal analysis, infrared spectroscopy, x-rays fluorescence and SEM. Three heating temperatures were evaluated: 750ºC, 850ºC and 900ºC, followed by pozzolanic activity tests based on traditional mechanical assays using Portland cement and hydrated lime mortars, and “Chapelle” test. The results showed that the more reactive pozzolans are those produced at temperatures that gave rise to higher LOI. The optimum burning temperature to produce metakaolinite from the hard kaolin was obtained at 750ºC while those from the Rio Jari and Rio Capim wastes were at 850ºC and 900ºC. The main reason is related to differences in the amounts of defects from three different wastes. The flint kaolin and Rio Jari waste are mainly composed by a “high-defect” kaolinite while the kaolinite from Rio Capim waste is a “lowdefect” kaolinite. In concrete test using different pozzolans those with metakaolin from wastes improved the mechanical and durability properties in comparasion to silica fume, a industrially manufactured metakaolin and reference concretes.
Acesso aberto (Open Access)
Aspectos litoestruturais e mineralizações Salobo 3A (Serra dos Carajás-PA)
(Universidade Federal do Pará, 1996-10-29) SIQUEIRA, José Batista; COSTA, João Batista Sena; http://lattes.cnpq.br/0141806217745286
The Salobo district is located at the Carajás Province in the Cinzento strike-slip system, and is formed of supracrustal rocks of the Salobo Group and gneisses of Xingu Complex, which were assembled by several generations of shear zones. The Salobo Group includes magnetite-fayalite schist, biotite-almandine-magnetite-fayalite-grϋnerite schist, biotite schist, anfibol schist, chlorite schist, banded iron formation and quartzite. The Xingu Complex includes banded tonalitic gneisses, trondhjemitc and granodiritic gneisses, partialy migmatized. The older shear zones correspond to ductile thrusts to which the generalized imbrication of the lithological units and the tectonic layering, defined by strips and lenses of supracrustais rocks alternated with gneisse is due. Their movements is synchronous to that of the Itacaiúnas belt; minerals transformations under thermal conditions of amphibolite facies, as well as important modifications in the stratigraphic relationships of several lithological units, are related to therm. The second generation of shear zones formed the transtensive Salobo-Mirim duplex. They are sinistral strike-slip shear zones, linked by normal shear zones along which minerals transformations of greenschist facies occurred. The development of the duplex was controled by the former tectonic layering, and its assymetric shape was influenced mainly by the presence of a basement gneiss megalense. The third generation of shear zones is of transcurrent type, with NW-SE and NNW-SSE trends, which modified the Salobo-Mirim duplex geometry, and are interpreted as X features linked to the sinistral moviments. The shear zones of the west corner of the area represent the propagation of a horse tail structure at the west end of the Carajás fault; in these case, they could be oblique thrust. The Salobo 3A deposit is situated in the central part of a normal oblique shear zone, which belongs to a release bend along the main strike-slip shear zone of the Salobo-Mirim duplex. The copper and gold mineralizations are hosted in extension structures, as single and composite pull-apart structures, transtensive sigmoide stringers, tension gashes, pressure shadows and star strucutures in the cross-cutting zones of descontinuities. The Salobo 3 A deposit is an example of concentracion/reconcentracion of cooper and gold mineralizations in s transtensive shear zone due to deformational, hydrothermal and metamorphic processes.
Acesso aberto (Open Access)
A associação anortosito-mangerito-granito rapakivi (AMG) do Cinturão Guiana Central, Roraima, e suas encaixantes paleoproterozóicas: evolução estrutural, geocronologia e petrologia
(Universidade Federal do Pará, 2002-12-19) FRAGA, Lêda Maria; COSTA, João Batista Sena; http://lattes.cnpq.br/0141806217745286
The geological mapping on a scale of 1:250,000, of an area of approximately 22,500 km2 in the central region of the state of Roraima, combined with the petrographic and microtectonic study and new geochronological, lithochemical and isotopic data, allowed the characterization of an anorthosite-mangerite association -rapakivi granite (AMG), Mesoproterozoic and its Paleoproterozoic host. Orthogneisses, foliated granitoids and charnockite rock bodies from the Serra da Prata Intrusive Suite show Pb-Pb (zircon evaporation) ages around 1.94 Ga, also inferred for the associated norites and gabbronorites. The Paleoproterozoic igneous suites were placed syn-kinematically, during Deformational Event D1, with the evolution of petroweaves indicative of high temperatures, from 600º-650ºC. These features include recrystallized feldspars by subgrain rotation, recrystallized perthitic alkali feldspars and quartz with checkerboard subgrains and have been observed in syn-plutonic dykes that cut the early-kinematic D1 fabric in the host country. The NE-NW arrangement of the Paleoproterozoic bodies was controlled by the previous structure of this sector of the Central Guiana Belt (CGC). The orthogneisses and foliated granitoids comprise two distinct suites, with lithochemical characteristics of type A granitoids, probably related to different oxidation conditions at the source. The charnockite rocks show chemical characteristics approaching those described for C-type magmatism. Sm-Nd TDM model ages between 2.19 Ga and 2.05 Ga, with ƐNd(T) values ranging from +0.68 to +2 ,47 suggested sources of limited crustal residence. The age of the orogenic events in Roraima has not yet been properly clarified, however, despite the limited data, a post-collisional positioning is proposed for the Paleoproterozoic suites studied after the accretion of transamazonian magmatic arcs. The Paleoproterozoic units constitute the basement of the Mesoproterozoic igneous suites, which comprise the anorthosites of the Repartimento unit and associated gabbronorites, the rapakivi granitoids of the Mucajaí Intrusive Suite (SIM), and the fine, porphyritic charnockites, of punctual occurrence and uncertain geochronological positioning. In SIM, three granite facies were identified (fayalite-pyroxene-quartz-mangerites to syenites; hornblende-biotite-granites; and biotite-porphyritic granites) geochemically and petrographically very similar to rapakivi granites from classical areas of Finland. The presence of fayalite in the most primitive rocks of the SIM indicates conditions of low oxygen fugacity, observed in several rapakivi granite complexes. Fine charnockites show no cpm to SIM chemical correlation. The Mesoproterozoic suites are part of an AMG (Anortosito-Mangerito-Granito rapakivi) association placed in an anorogenic environment between 1.54 and 1.53Ga. Model ages Sm-Nd, from 2.07 Ga to 2.01 Ga with ƐNd(T) values ranging from -2.37 to -1.27 suggest, for the granitoids in the association, crustal sources separate from the mantle in the Paleoproterozoic , probably during the Transamazônico. Mylonitic features related to the D2 Deformational Event, registering conditions of moderate to low temperatures (400º-450ºC), in a brittle-ductile environment, locally obliterate the igneous textures of the Mesoproterozoic units, as well as the high temperature D1 petrowebs in the Paleoproterozoic basement. These features are especially well developed in some shear zones that show dextral transpressive kinematics. The D2 event aged around 1.26 Ga relates to the K'Mudku Deformational Episode. The main D2 mylonitic zones were reactivated in the Mesozoic at shallow crustal levels and brittle conditions, during the evolution of Graben Tacutu.
Acesso aberto (Open Access)
Biogeoquímica dos sedimentos lamosos e sua influência no padrão de distribuição da vegetação, no manguezal de Bragança, NE do Pará.
(Universidade Federal do Pará, 2009-10-30) CRUZ, Cleise Cordeiro da; LARA, Rubén José; http://lattes.cnpq.br/8695520453124286; 8695520453124286
The present study investigates the relationship between sediment-plant and biogeochemical processes involved in the development and spatial distribution of vegetation in the Bragança mangrove peninsula, exposed to macrotidal regime (spring range 4 m). Therefore, three transects were established at three different topographic levels of that peninsula being colonized by different patterns of vegetation: Transect 1 (T1) Transect 2 (T2) and herbaceous plateau (PHb). The vegetation in T1 is composed mainly by Rhizophora mangle and Avicennia germinans and it is situated in a semi-diurnal flooding regime forest. The transect T2 is less frequently flooded and is characterized by a stand of young Avicennia trees and herbaceous vegetation. In the highest part of this transect with low inundation frequency and high salt stress, the vegetation is dominated by shrubs of A. schaueriana coexisting with herbaceous vegetation of Sesuvium portulacastrum and Sporobolus virginicus. The PHB, localized in the zone with lowest inundation frequency is colonized mainly by tree species of A. schaueriana in the form of shrubs and S. portulacastrum and S. virginicus with sporadic presence of B. maritima. In these sites were performed measurements of the flooding frequency; floristic and fitossociologic inventory in mangrove forest and in the herbaceous halophyte vegetation. Also sediment cores (0-30 cm) and vegetation (leaves, stems and roots) were collected. The sediment samples were subjected to granulometrical, mineralogical and chemical (total sample) analyses, and determination of the humidity, organic matter and salinity as well as cation exchange capacity (CEC) besides determination of the total, inorganic, organic and bioavailable phosphorus. In the vegetation samples, chemical analysis of total phosphorus was performed. The variance analysis (ANOVA) One Way (Post Hoc Fisher's test) was applied to test the mean of the variables (humidity, salinity, organic matter, total-P, inorg.-P, org.-P and bioavailable-P. Discriminant analysis was used to measure the degree of influence of environmental variables (humidity, salinity, organic matter and total-P) in the discrimination of sites sampled. The correlation analysis of Pearson was used to evaluate the degree of interaction between discriminated variables with the hydrological conditions and forest structure data. Fine sediments (clay) in T1 and T2 suggest areas of slow deposition, while in the plateau high levels of sand suggest its formation on a paleodune with intense eolic reworking of sandy and tidal input of finer sediments. The main mineralogy of the sediments is composed of quartz (dominant in the sand and silt) and clay minerals: kaolinite and illite, other minerals of authigenic origin are pyrite, jarosite and vivianite and possibly smectite and k-feldspar. The main mineralogical and chemical composition of major and trace elements indicate the influence of sediments and soils of the Barreiras Formation on the genesis of sediments mangroves and marine influence in their chemical composition. In T1 (the more flooded sector), the dominant species is R. Mangle, while in T2 (less flooded zone) the Avicennia genus is predominant. In the herbaceous plateau the dominance of the S. portulacastrum species, is five times higher than that of S. virginicus, indicating that Sesuvium has greater ability to survive in environments with salt stress. The flooding gradient results in highly significant positive correlation with humidity. This trend is reflected in the tree height, volume and basal area correlated significantly with sediment phosphorus availability in T1 and CEC in T2. The results of Discriminant Analysis show that in T1 the humidity is the variable that most contributes in the discrimination of (Rhizophora and Mixed) forest of the Avicennia forest, while organic matter (OM) discriminated the Mixed forests and Rhizophora forests. In T2, the humidity, total-P and salinity are the variables that most contribute to the discrimination of sites in this transect. In the profiles, along the plain, the total-P and organic mater were the most important variables for discrimination of T1, T2 and PHb. The distribution of vegetation reflects different ecophysiological responses to environmental gradients. Therefore, the combination of organic matter, salinity, and phosphorus and, the high cation exchange capacity of sediments represent a significant role in the colonization of vegetation in the peninsula of Bragança.
Acesso aberto (Open Access)
Braquiópodes devonianos da Bacia do Amazonas: novos dados taxonômicos, paleobiográficos e relações com as mudanças ambientais
(Universidade Federal do Pará, 2024-10-01) CORRÊA, Luiz Felipe Aquino; RAMOS, Maria Inês Feijó; http://lattes.cnpq.br/4546620118003936; https://orcid.org/0000-0003-0276-0575
The Devonian marked a significant phase in the evolutionary history of the Brachiopoda. During this period, the Phylum achieved its peak diversity (Emsian) and suffered one of its most significant declines (Frasnian–Famennian), ranking second only to the mass extinction event Permo-Triassic. Among the Brazilian sedimentary basins, the Amazonas Basin has the greater diversity of Devonian brachiopod genera, distributed among the following formations: Manacapuru (Lochkovian), Maecuru (early Eifelian), Ererê (Late Eifelian), and Barreirinha (early Frasnian). Studies of Devonian brachiopods from the Amazonas Basin began in the late 19th century with identifications of material collected during the Morgan Expeditions (1870–1871) and the Imperial Geological Commission of Brazil (1876). These expeditions focused primarily on the Maecuru and Ererê formations. The brachiopod fauna of the Manacapuru Formation (Lochkovian) was unknown until 2015, when during paleontological salvage at the Belo Monte hydroelectric plant in Vitória do Xingu, Pará, Brazil, a significant number of Rhynchonelliformes and Linguliformes samples were recovered. This work aims to carry out the taxonomic identification of brachiopods from the Manacapuru Formation, in addition to analyzing and discussing the possible factors that influenced the diversity of brachiopod genera among the sedimentary units of the Amazonas Basin (Mancapuru, Maecuru, Ererê, and Barreirinha formations). The taxonomic study of brachiopods from the upper part of the Manacapuru Formation (Lochkovian) has allowed, to date, the identification of two genera, Orbiculoidea d'Órbigny, 1847 and Schellwienella Thomas, 1910. Among the materials, Orbiculoidea has the greater diversity, totaling five species: Orbiculoidea baini Sharpe, 1856, Orbiculoidea bodenbenderi Clarke, 1913 and Orbiculoidea excentrica Lange, 1943 in addition to two new species: Orbiculoidea xinguensis Corrêa & Ramos, 2021 and Orbiculoidea katzeri Corrêa & Ramos, 2021. The species O. baini, O. bodenbenderi, and O. excentrica were recorded for the first time in the Manacapuru Formation and Northern Brazil, and they are also the oldest records (Lochkovian) from South America. The presence of Orbiculoidea in the region can be explained by two reasons: the proximity of the Amazonas Basin, located in the northwest of Gondwana during the Lower Devonian, with the paleocontinent Laurussia (where most occurrences of Orbiculoidea are recorded during the Silurian), favored the specific exchange between these two geographic regions; and the global rise in sea level during this period, which flooded much of northwest Gondwana, resulting in the presence of shallow seas in the Amazonas Basin, represented by marine sediments in the upper part of the Manacapuru Formation. These conditions favored the colonization of inarticulate brachiopods during the Early Devonian in northern Brazil. Furthermore, the new species Schellwienella amazonensis Corrêa et al. 2024, of the Pulsiidae Family Cooper and Grant, 1974, is proposed, this being the first record of the genus in the Amazonas Basin. Schellwienella amazonensis n. sp. and Schellwienella marcidula Amsden, 1958 from the Bois d’Arc Formation (Lochkovian), USA, are the oldest records of the genus. In the Devonian, Schellwienella occurred in all stages (Lochkovian, Pragian, Emsian, Eifelian, Givetian, Frasnian, and Famennian), mainly in the marine siliciclastic environments of Gondwana, transiting between temperate and polar latitudes. In the Carboniferous, its stratigraphic distribution was restricted to the Tournaisian-Visean interval, with a preference for warm water environments and carbonate platforms typical of low latitudes. We identified three distinct stages when analyzing the variation in Devonian brachiopod diversity in the Amazonas Basin. In stage 1, the peak of brachiopod diversity occurred in the early Eifelian (Maecuru Formation), when the Amazonas Basin was between subtropical latitudes 30°S and 60°S, under shallow and cold marine conditions, justified by the absence of carbonates, evaporites, and reefs in the region. In stage 2, the first decline in diversity occurred, recorded in the Ererê Formation (late Eifelian), attributed to a warmer climate and deeper waters than in the Maecuru Formation. Stage 3 occurred during the Frasnian when there was a second decline in brachiopod diversity in the Amazonas Basin (Barreirinha Formation). A major global transgression happened at the end of the Devonian. During this period, the Amazonas Basin experienced the deepest marine conditions in its history. Brachiopods of the Barreirinha Formation occur in black shale layers (offshore), attributed to a dysoxic to the anoxic environment of high stress, which explains the low diversity of brachiopods in this unit.
Acesso aberto (Open Access)
O Camp nas bacias dos Solimões, Amazonas, Parnaíba e Parecis, Norte do Brasil: implicações geotectônicas e deposicionais para o jurássico do Gondwana Ocidental.
(Universidade Federal do Pará, 2024-08-23) REZENDE, Gabriel Leal; NOGUEIRA, Afonso César Rodrigues; http://lattes.cnpq.br/8867836268820998
Geological studies in conjunction with applications of geophysical techniques are being widely used to highlight and characterize CAMP gravimetric anomalies throughout Northern Brazil, including the Solimões, Parecis, Amazonas and Parnaíba basins. Interpretations of a residual gravimetric anomaly from these basins were used to expand the understanding of the distribution of CAMP throughout the subsurface. This study was carried out through qualitative and quantitative interpretations of gravimetric data, supported by surface geological information, mainly stratigraphic data based on outcrops. From direct gravimetric modeling, based on available crustal gravitational structure models to separate a residual gravity signal from observed gravity data, realistically detailed geological and tectonic features were interpreted, providing useful information for a geophysical interpretation of geological sources. With the residual gravity anomaly, a map of the elastic thickness (Te) of the basins was obtained, using a new procedure, presumably allowing some gaps presented in the current literature on the CAMP to be filled. For each Te value, the residual gravimetric signal was calculated, considering the surfaces described by topography and Moho for a regional model with standard density and discretized into prisms. The cross-correlation between the observed gravity signal and calculated gravity signal made it possible to obtain a map of the elastic thickness of the studied areas. The highest correlation value is directly related to the best value of elastic thickness and Moho depth associated with crustal deformation. Our study used a combination of these techniques to presumably define the possible extent of Jurassic magmatism, the basin rheology of igneous body intrusion and history of thermal subsidence that largely controlled depositional control during and after the CAMP. The presence of low gravity values is closely related to the less dense lithological units of the upper crust, while the high gravity values are related to high-density rocks correlated to the continental tholeiitic flood basalts of the CAMP. The use of residual gravity anomaly based on crustal modeling combined with previous geological data was effective in identifying the CAMP record in these Amazonian sedimentary basins. Furthermore, some gravimetric signatures correlate well with the main structural discontinuities, particularly with the Monte Alegre Dome and Xambioá, Serra Formosa and Vilhena arches, respectively, in the Amazon, Parnaíba and Parecis basins. This interpretation provides a reasonable explanation for understanding structural lineaments without exclusively tectonic connotations, assuming a new interpretation for the gravitational field related to intracrustal density contrast or residual gravity field for these basins. Eastern Gondwana was gradually uplifted by subvolcanic bodies of the Penatecaua magmatism in the Amazon and Solimões basins. In contrast, extrusive volcanism characterizes Mosquito magmatism in the Parnaíba basin interspersed with intertrap sediments. Information obtained from the elastic thickness map, Moho depth and residual gravity signal indicate a thinner crust in the Parnaíba basin favoring the magmatic eruption induced by a hot spot installed on the western edge of the basin. On the other hand, in basins with denser and thicker crust, magma accumulates mainly as sills, providing greater resistance to rupture due to the swelling of the CAMP. The Parnaíba Basin experienced three magmatic pulses at intervals of approximately 1 Myr, alternating with the development of aeolian-fluvial-lacustrine systems (intertrap sediments) during non-magmatic periods, indicating short intervals of magmatic resump-tion and cooling in the CAMP, contrasting with the longer and continuous magmatism in the Amazon and Solimões basins, which lack intertrap deposits. These results are important for a new disposition of the tectonomagmatic, structural and stratigraphic history for these basins, since from a new context or geological evolution for the area it will allow a better understanding of the studied basins in lava-sediment interaction, preserved from the Jurassic and related to the CAMP events, which preceded the main continental rupture in northwestern Pangea.
Acesso aberto (Open Access)
A capa carbonática marinoana do Sul do Cráton Amazônico: multiproxies aplicados na reconstituição paleoceanográfica e geobiológica do início do Ediacarano.
(Universidade Federal do Pará, 2024-08-30) SANTOS, Renan Fernandes dos; SANSJOFRE, Pierre; NOGUEIRA, Afonso César Rodrigues; http://lattes.cnpq.br/8867836268820998
The post-Marinoan glaciation (~650-635 Ma) was the most severe event from the late Cryogenian period of the planet. The snowball Earth conditions induced a climate anomaly, triggering major changes in the paleoenvironmental and ocean chemistry recorded in the carbonate cap sequences. The dramatic effects on the global sea level were caused by glacial-isostatic adjustment (GIA) and ice gravity on the coastal zones associated with the ocean thermal expansion under greenhouse conditions. The fast input of meltwaters contributed to a stable density ocean stratification formed by hypersaline deep waters and meltwater surface layers. The ocean destratification occurred in a timescale ranging from tens of thousands to thousands of years. The Puga cap carbonate (~635 Ma), the basal deposits of the Araras-Alto Paraguai basin from the southern Amazon Craton, is revisited in the classical sections from the Tangará da Serra and Mirassol d'Oeste, Mato Grosso State. This succession is one of the best records for evaluating the supersaturation events under GIA and transgression conditions that controlled the accommodation space in the southern Amazon Craton. Sedimentological and stratigraphic data were integrated with new paleoceanographic, and paleo-redox data combined with diagenetic, crystallographic, geochemical (primarily rare earth elements and trace metals), and isotopic (whole rock 87Sr/86Sr, εNd(t), δ 13C, δ 18 O, Sm/Nd) results providing further insights to understand the post-Marinoan conditions. The Puga cap carbonate sequence spans approximately 90 meters, with the first 10 meters composed of glaciomarine deposits, diamictites, and dropstones from the Puga Formation. The basal contact with diamictites is plastically deformed, indicating rapid carbonate precipitation. The cap dolostone consists of stratiform doloboundstones with gypsum pseudomorphs and domal doloboundstones with tubestone, which were deposited in a shallow platform with intense microbial activity. Peloidal dolomudstone/dolopackstone with laminations parallel to bedding planes and peloidal dolograinstones/dolomudstone with quasi-planar laminations and low-angle truncation were formed in a wave-influenced shallow platform. The cap limestone conformably overlies the cap dolostone deposits, marked by dolomitic marlstone with calcite crystal fans (aragonite pseudomorphs) interbedded with mega-rippled limestone. The facies association of the cap limestone indicates moderately deep-water conditions dominated by waves and storms transitioning to a deep platform supersaturated with CaCO3. The main diagenetic process is dolomitization during syn-depositional and shallow burial stages. Rare earth element + yttrium patterns have been analyzed in these deposits. Low Y/Ho ratios (<36) in the cap dolostone suggest a mixture of meltwater and seawater, while the base records superchondritic Y/Ho values up to 70 and high Eu/Eu* values up to 3, indicating upwelling of hypersaline seawater with hydrothermal fluid interaction, suggesting dolomite precipitation during ocean destratification. The radiogenic isotopic compositions of Nd, combined with other proxies such as δ 13C and 87Sr/86Sr, indicate the influence of continental and marine contributions. The Nd isotopic system, less susceptible to diagenetic exchanges, revealed distinct signatures of water masses and enhanced weathering of the Amazon Craton during deglaciation. This process is indicated by geochemical trends (e.g., Y/Ho) and 87Sr/86Sr, εNd(t), δ 13C values. 87Sr/86Sr data in the cap dolostone range from 0.7264 to 0.7084, higher than pre- and postglacial seawater values. More radiogenic 87Sr/86Sr values associated with less radiogenic εNd(t) values, similar to those found in diamictites, reinforce coastal weathering contribution to meltwaters. This multiproxies approach is a reconciliation with the previous rapid cap carbonate precipitation model following the short-term timescale for ocean destratification. Redox-sensitive trace metal data, U, Mo, V, Ni, Cu, P, and δ13C isotopes, indicated paleo-redox states and paleoproductivity during the post-glacial transgression. The cap dolostone precipitated under oxygenated conditions with extensive microbial community contributions, transitioning to predominantly dysoxic conditions with wave action in the last deposition phase. The abrupt sea-level rise altered the biogeochemical cycle, indicating a direct relationship between oxygen production and rapid microbial community colonization. The rapid sea-level rise and continental weathering reduced seawater Mg/Ca ratios with substantial Ca2+ input, also demonstrated by εNd(t) values, causing the change of dolomitic platform to CaCO3 -supersaturated seas in the Amazon Craton margin. Additionally, low siliciclastic content in the cap dolostone is consistent with the siliciclastic starvation model, and the abrupt increase caused the decline of microbial communities coincident with the predominance of dysoxic conditions and longterm transgression. During specific Cryogenian-Ediacaran deglaciation scenarios, anomalous sedimentary and geochemical processes generated one of the most complex paleoenvironmental disturbances in the biogeochemical cycle. They strongly influenced the rapid primary productivity, directly impacting microbial life. The analysis of Precambrian scenarios in the Amazon Craton unraveling the extreme climates sheds critical light on extremophile life proliferation and has strong implications for understanding other planetary surfaces.
Acesso aberto (Open Access)
Caracterização geomorfológica estratigráfica e geoquímica da Planície Costeira do município de Itarema-CE.
(Universidade Federal do Pará, 2011-09-01) PEREIRA, Lamarka Lopes; FREIRE, Geoerge Satander Sá; http://lattes.cnpq.br/6803944360256138; 6803944360256138; EL-ROBRINI, Maâmar; http://lattes.cnpq.br/5707365981163429; 5707365981163429
The Itarema coastal plain, situated at the western coast of Ceará, in the area dominated by the Cenozoic sedimentary cover. This thesis shows the geomorphological, sedimentological and geochemical features of this coastal plain. The Itarema coastal plain is subdivided in two major morpho-structural units: pre-coastal ¨plateaus¨ and coastal plain, that is subdivided into lithostratigraphic units, lagoon plain, tidal plain with and without mangroves, marine and fluvial plain, mobile and fixed dunes, beach ridges, tidal channels, sand bars and beaches. The supply and sediment transport in the area are closely linked to the climatic, meteorological and oceanographic conditions. The sedimentary, stratigraphy, geomorphological and geochemical data have been defined: (1) five lithological units: Lagoon Deposits, dune deposits, eolianits deposits, beach deposits and alluvial deposits and (2) seven lithofacies: mud sandy, mud, Sand mud, fine sand, medium sand, thick sand, conglomeratic sand-clay with different characteristics which have been drawn through the lateral and vertical correlations, thus allowing the interpretation of depositional paleoenvironments related to the evolution of the Itarema Coastal Plain. The analysis of the lithological units allowed the reconstruction of the processes indicative of a transgressive sucession prograded during which the lagoon-barrier system was installed on the system of alluvial fans, the bus of small streams, forming the lagoon plain, it was also noted that the lagoon has undergone changes in their size both by progradation of the barrier and subsequently by the deposition of sediments within the same wind. The Itarema coastal plain presents physiographic features of an coastal promontory or embaiments of central nuclei as a spiral, that would have provided the evolution to the current environment and the current model of coastline with beaches of the barrier beach-type and suggests that is occurring repetition in the construction of comparative morphology morphogenetic active in the region's past.
Acesso aberto (Open Access)
Compartimentação morfotectônica do interflúvio Solimões-Negro
(Universidade Federal do Pará, 2003-11-26) BEZERRA, Pedro Edson Leal; SILVA, Maurício Borges da; http://lattes.cnpq.br/1580207189205228
From the morphostuctural and morphotectonic analysis integrated to the informations of remote sensing images, litoestratighaphy , geomorfology , the seismic data and field investigations was defined the neotectonic structuration and its influence in the elaboration of the relief forms and drainage net during the Upper Tertiary and Quaternary. This relation is shown through the morphotectonic compartimentation of the Solimões-Negro watershed, subject of this research (SA.20-Manaus Sheet). The discussions concentrated in the area of the cenozoics covers which overlay the east and west borders of the Solimões and Amazon paleozoics sedimentary basins, respectively. This area occupies about 290 000 km2, and is situated between the parallels 0° and 4° S and meridians 60° and 66° WGr, in the Amazonian region, involving parcels of Amazon and Roraima States. The geologic units formed during, or imediatelly after, the implantation of the neotectonic regimen are represented by: 1) the Içá Formation formed after the Miocene, probably of the Plio-Pleistocene age; 2) the Pleistocenics Terraces; 3) the Holocenics Terraces; 4) the inundatable watersheds areas of holocenic age; and 5) the Holocenics Alluviums. The modelling of the landscape for the drainage net evidences a relief compartimentation at plains systems, linked to the actual fluvial dynamics, and depressions, normally leveled by a planing surface formed in the Middle Pleistocene, in retaken by erosion, and preserved on tabular watershed. The neotectonic structuration has a direct relationship with the regeneration of the discontinuities of the paleotectonic structuration, that is, with the resurgent tectonic . This old estructuration is defined by: 1) Tacutu Lineament of NE-SO orientation, that show continuity to the northwest quadrant of the area; 2) the Madeira Lineament, also of NE-SO orientation that section the Southeastern quadrant; 3) the Purus Arc with NW orientation that establishes the limits between the Solimões and Amazon basin; e (4) minors lineaments as the Juruá and the Japurá ones, of E-O direction, defined outside of the domains of the research area. The neotectonic tensions field was alliviated through two kinematics pulses of essentially transcorrent nature. In the first pulse, occurred immediately after the inversion of the Amazonian Occidental drainage for east, had established the main corridors of drainage in the predominant NE-SO direction through the northeast of Amazonas and Roraima states in the brasilian territory, reaching the Guyana Republic and the Atlantic Ocean through rift valley of the Tacutu. The second one, predominantly transtensive, occurred in the Upper Pleistocene /Holocene, provoked the redirectioning of this system for the Amazonas hidrographic basin, and answers for the actual configuration of the relief and drainage net. The Relief Systems are differentiate for the degree of development of the drainage net, showing a evident gradation from the most evolued to the less evolued, that is reflected in the configuration of the watershed and its dimensiona, and that register the history of the implantation of the neotectonic structural picture and its geometric and kinematic differentiations. This register is represented through five morfotectonics compartments, called: Juruá River - Purus River Tanspressive Compartment; Madeira River - Purus River Transcorrent Compartment; Negro River- Japurá River Trancorrent Compartment; Negro River - Solimões River Trantensive Compartment; and the Branco River- Negro River Transtensive Compartment. The morphostructural and morphotectonic evolution occurred from southwest to northeast. So, the drainage net show best developed in the Juruá River — Madeira River Compartment; it is in development in the central zone formed by the Madeira River - Purus River, Negro River-Japurá River and Negro River- Solimões River Compartments; and show a initial stage of development in the Negro River- Branco River Compartment. In the northeast border of the Negro River Japurá River Transtensive Compartment, the development of the drainage net is composed, showing features of initial stage, as the amorphous and multibasinal pattern, with other typicals features of drainage net in development. The structures of the Juruá River Purus River Compartment are generated by inverse faults in the Upper Tertiary. In the the Madeira River - Purus River and Negro River — Japurá River compartments they are dextrals directional faults with component of oblique slip, probably of the reverse type in the Tertiary Superior and normal in the Pleistocene; in the Negro River - Solimões River Compartment they are mainly normal and oblique-dextrais types in the Upper Pleistocene. The Negro River- Branco River Compartment configures a wedge structure with oblique movement in the northwest and east borders, and extensional in its central zone, with evolution initiated in the Upper Pleistocene extending to the Holocene. Recent activity of some of these faults is marked by seismic events with intensities that arrive 5,5 mB.
Acesso aberto (Open Access)
Cristaloquímica de esmectitas dioctaédricas em bentonitas brasileiras
(Universidade Federal do Pará, 2025-07-01) VEGA PORRAS, David Enrique; PAZ, Simone Patrícia Aranha da; http://lattes.cnpq.br/5376678084716817; https://orcid.org/0000-0002-5880-7638
Bentonites are mineral inputs of great industrial interest due to the physicochemical properties of clay minerals from the smectite group. These properties, resulting from the complex crystal chemistry and small particle size of smectites, include various layer charge, swelling capacity, and cation exchange capacity. In Brazil, the main bentonite deposits are located in the municipality of Boa Vista, Paraíba, which accounts for >70% of the country’s production. However, the progressive depletion of these varieties has motivated the search for new deposits. Among them, the Formosa deposit, in the state of Maranhão, stands out. Although both the Boa Vista and, to a lesser extent, the Formosa bentonites have been extensively studied in their <2 μm or coarser fractions, the crystal chemistry of their smectites has not yet been fully elucidated. This is due not only to the typical chemical and structural complexity of smectites, but also to the difficulty of obtaining pure smectite phases and the interference of accessory minerals. In this context, this thesis presents a detailed study of the crystal chemistry of smectite from the Formosa deposit, comparing it with three commercial varieties from Boa Vista: Bofe, Chocolate, and Verde Lodo. The <2 μm, 0.1-2 μm, and <0.1 μm fractions were analyzed, with the latter being the main focus of the study. The analyses included XRD (Rietveld method), FTIR, TEM-EDS, SEM, XRF, AAS, TG, and Mössbauer spectroscopy. These smectites, previously described as montmorillonites, also exhibit significant tetrahedral layer charge. In fact, the four samples show a tetrahedral charge of approximately 0.15 per half unit cell, sufficient to induce swelling after the Hofmann-Klemen treatment. The octahedral symmetry of all four samples was trans-vacant, influenced by both the Fe content and the tetrahedral charge. The structural and chemical similarities between the Formosa and Boa Vista smectites, along with similar smectite content in the <2 μm and <0.1 μm fractions – as quantified by the Rietveld method – demonstrated that the Formosa deposit is a potential alternative to the Boa Vista bentonites.
Acesso aberto (Open Access)
Desenvolvimento de processo para obtenção de zeólita do tipo faujasita a partir de caulim de enchimento, caulim duro e tube press: aplicação como adsorvente.
(Universidade Federal do Pará, 2015-03-31) ROCHA JUNIOR, Carlos Augusto Ferreira da; NEVES, Roberto de Freitas; http://lattes.cnpq.br/9559386620588673; 9559386620588673
The main purpose of this work is zeolite synthesis of faujasite type (X and Y) from kaolin from the beneficiation process for paper coating, hard kaolin or Flint (mining of waste), tube press kaolin and filler kaolin. For each process zeolitização kaolin used in a chemical reactor a product of calcination of each material (metakaolin), sodium metasilicate, solid sodium hydroxide and distilled water, subjected at 110 ° C, reaction time 13 h Si / Al ratio of 2, 4 and 6. The products of each zeolite synthesis as well as the starting kaolin were characterized by chemical, physical and mineralogical analyzes such as X-ray diffraction, X-ray fluorescence, electron microscopy scan and thermal analysis. From these tests, it was observed that all the kaolin showed the formation of faujasite zeolite, but with differences in the peak intensities and their associations with other zeolite phases. Hard kaolin showed a lower potential zeolitization into the Si / Al ratio equal to 2 compared with the other two supposedly related to the iron present in its composition, thus made was a removal process of this constituent, by Mehra and Jackson method to verify a possible maximization in the synthesis process. New results indicated a complete modifications to the area and degree of structural order of faujasita phase, now moving into a major phase and there is an increase in the degree of structural order. As this reaction condition for consumption and a lower cost of raw materials and energy for calcination This medium was used as a starting point for an experimental design to evaluate the best reaction conditions. This design was varied some parameters of the synthesis as temperature, reaction time, Si / Al ratio and H2O / Na2O. The results of the statistical design showed the formation of faujasite in 32 points of study, as well as a great region with 8 points of planning, in this region point 13 proved the best reaction conditions. The zeolite synthesized at this point, showed an increase of ammonium adsorption capacity and percentage near 85 % efficiency up to 60 ppm. The Langmuir model was more suitable than the Freundlich and Sips in agreement with experimental data. The thermodynamic parameters showed that adsorption of NH4 + is a spontaneous and exothermic process, in which the temperature rise from 25 to 60 ° C promotes a small decrease in the adsorption capacity.
Acesso aberto (Open Access)
Desenvolvimento do processo de síntese da zeólita A e da sodalita a partir de rejeitos de Caulim da Amazônia com aplicações em adsorção
(Universidade Federal do Pará, 2011-08-31) MAIA, Ana Áurea Barreto; POLMANN, Herbert; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; 7501959623721607
The minimization of industrial and domestic residues is one of the great challenges that human kind is facing. Several proposals are released for this intention, ranging from improving industrial processes in order to minimize waste generation, besides their use in the production of new materials. In this context, this work has the main purpose of using kaolin residues from industries located in the Pará State, northern Brazil, for the production of zeolites (e.g., zeolite A and sodalite). These companies exploit kaolin from the world famous Capim and Jari regions and produce high quality kaolin for the paper industry. Preliminary mineralogical and chemical characterization of the Capim (KC) and Jari (KJ) kaolin residues was carried out as the basis for further zeolite A and sodalite synthesis. The study of thermal activation of kaolinite at various temperatures was carried out using 27Al and 29Si magic angle spinning nuclear magnetic resonance (MAS NMR), in order to to produce highly reactive metakaolinite from KC and KJ residues. The zeolite NaA synthesis was performed for varying parameters such as time and Na/Al relation. Temperature was kept constant at 110 °C for the two starting materials (KC and KJ). The KA, MgA and CaA phases were prepared by ionic exchange from phase NaA. In the sodalite synthesis, kaolinite was used directly as starting material and two temperatures (150 and 200 °C) were utilized. The Na/anion and Na/Al relations were maintained constant and varied, respectively in the reaction mixture for KC and KJ. The removal performance of mixed metal ions (Co2+, Cr3+, Cu2+, Zn2+ e Ni2+) in aqueous solution was investigated by adsorption process on zeolite NaA prepared from KC an KJ as proposal to reduce environmental problem with industrial wastewater streams that contain heavy metals. The XRD results showed that the residues are mainly composed of kaolinite with extremely low impurity level. For comparing the residues from two regions, Capim and Jari verified that the KC displays a high degree of structural order. This difference displays significant influence in the ideal heating temperature to produce a material with high amount of 4-coordinated A1. As a result, the ideal temperature to produce highly reactive metakaolinite is: 600 °C for Jari kaolin residue and 700 °C for Capim kaolin residue. Zeolite A was produced with a large degree of structural order and was generally obtained as the only zeolitic product. The following synthesis conditions were used: Na/Al ratio of 1.64 and time 18 and 20 h for KC and KJ, respectively. The cationic exchange process between Na from zeolite A and K, Mg and Ca in solutions displays efficient result and with XRD data, was verified that the KA, MgA and CaA phases were obtained with success. The sodalite series was produced from KC and KJ and by FTIR was confirmed the chloride, sulphate and carbonate insertion in its structure. The KJ kaolinite displays high reactivated in the sodalite synthesis, it could be explicated by its low degree of structural order. The sorption capacity of heavy metals mixture (Co2+, Cr3+, Cu2+, Zn2+ e Ni2+) on zeolite NaA, produced from KC and KJ, display satisfactory values. The results revealed that the Langmuir model is more appropriate than Freundlich in the fit of the experimental data. Zeolite A, produced from residues (KC and KJ), could be excellent materials for the treatment of wastewater.
Acesso aberto (Open Access)
A dinâmica dos manguezais no Nordeste do Brasil: uma abordagem a partir de dados de sensores remotos e SIG.
(Universidade Federal do Pará, 2015-11-27) PEREIRA, Edson Adjair de Souza.; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252; 3282736820907252
This study assesses the dynamics of mangroves in the northeastern Brazil in the last four decades from the classification of remote sensing images based on geographic objects (GEOBIA). This methodology combines spectral, temporal and spatial information of multi-temporal images to create consistent objects (mangrove areas) for a statistical analysis from classified images. The objective of this study was to evaluate the changes in mangrove forest cover in all states of the northeastern Brazil between 1975 and 2008, with regard to the increase or decrease mangrove areas in response to natural (erosion and accretion) and anthropogenic (Aquaculture / salinicultura) variations. In this study were processed and analyzed remote sensing images (RADAMBRASIL, ALOS PALSAR, TM Landsat and SRTM) from GEOBIA approach. During the studied period, there was a reduction of ~ 1,545 km2 mangrove forest area in 1975 to ~ 1480 km2 in 2008. This represents a net loss of ~ 65 km2, which is equivalent to a decrease of 13% in the mangrove forest area. Of the nine states studied, only Ceará and Pernambuco showed a gain in coverage of mangroves, while all others were reduced. Among the total mangrove forest area lost during the study period (~ 953 km2), the aquaculture/saliniculture ponds represent ~ 10%. Importantly, in the states of Rio Grande do Norte and Ceará the conversion of mangrove areas for aquaculture/saliniculture ponds already represent ~ 41% and 32% of the total area of mangrove lost, respectively. Therefore, it concludes that the methodology used to assess the dynamics of mangroves in northeastern Brazil from different sources of remote sensing data was extremely effective. New strategies for recovery and sustainable use of mangrove areas should be established in order to conserve this ecosystem for future generations.
Acesso aberto (Open Access)
Efeito do tempo de síntese de zeólita A a partir de caulim amazônico, conformação por extrusão e verificação desta na eficiência de adsorção de NH4 +
(Universidade Federal do Pará, 2015-04-24) SANTOS, Suzianny Cristina Arimatéa; NEVES, Roberto de Freitas; http://lattes.cnpq.br/9559386620588673
Kaolin is widely used in the field of materials (ceramics, pozzolans, fillers and manufacture of paints) as much as the waste and the product received. Currently the most exploited use has been in zeolite synthesis, as it presents the most noble applications. Zeolites are synthesized from silicon and aluminum sources, a fact that justifies the use of kaolin, because it is formed essentially by the clay mineral kaolinite (Al2Si2O5 (OH) 4). In this work we made a kaolin comparison of Grass River region with kaolin mineralogical / chemical and other Amazon kaolin reference to see if you can make it a reference material. The comparison was carried out by size analysis, X-ray diffraction, X-ray fluorescence, scanning electron microscopy, differential thermal analysis and infrared spectroscopy and crystallinity calculations. Moreover, the kaolin of the Rio Capim region was used as a source of silicon and aluminum to obtain the zeolite in order to determine the effect of time on the synthesis. Assays were performed in a time of 30 min, 1 h, 2 h and 24 h applied in these zeolites ammonia adsorption. From the synthesized zeolite was carried out the forming process by extrusion, evaluating various ligands (sodium silicate, bentonite, kaolin and CMC) and firing temperatures (500, 700 and 800 ° C). Later, these were extruded applied also in ammonium adsorption to check its efficiency. It was observed that it is possible to use kaolin Grass River as mineralogical reference material (high degree of structural order) and/or chemical, because it showed performance equal or close to the reference kaolin compared in this work. The zeolite A was synthesized from Amazon kaolin and this presented an excellent silicon and aluminum source. All synthesis times gave zeolite A zeolite in amounts of ~ 600 g. All zeolites showed a high degree of structural view to XRD and SEM. It was also found that synthetic zeolite A in 30 minutes time can be performed without loss in its application, since it presented below only 3% difference in adsorption efficiency compared to 24 h. The shaping by extrusion tests proved promising, 5 out of 10 trials were successful in obtaining granulated with physical strength. However, only the granules containing sodium silicate and CMC as a binder showed a high ammonia adsorption efficiency. With values of ~ 95,5% efficiency in 24 hours of contact.
Acesso aberto (Open Access)
A Evolução da paisagem de transição savana-floresta em Roraima durante o Holoceno tardio: base mineralógica, geoquímica e palinológica
(Universidade Federal do Pará, 2011-01-10) MENESES, Maria Ecilene Nunes da Silva; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
The Amazonia includes several vegetation physiognomies, besides the large and well-known tropical forest. The savannas, for instance, are present in several areas as discontinuous patches or covering extensive areas as it is the case of the savannas found in the north and northeast portions of the Roraima state. These savannas belong to the so-called Rio Branco-Rupununi Complex considered the largest continuous block of that vegetation type in the Brazilian Amazonian which in the state of Roraima covers about 41.000 km2 of a total of 53.000 km2 being limited to the south and west by tropical forests. In order to understand the vegetational dynamic and the evolution of the whole landscape in face of the possible climatic changes occurred along the geological time, the present study was carried out. The chosen area for this work represents a zone of transition between savannas and forests in the western portion of the savanna block, where four topossequences (FC, FH, TIA and RU) representative of the relief, vegetation and pedological cover patterns were selected for sampling. Then, samples of the regolith cover were collected starting at the base of the topossequences (veredas) until their top parts following the visible texture and color variations of the materials. Additionally, other two veredas (AM and MB) were also cored. These regoliths samples were submitted to analyses such as granulometrical by wet sieving; mineralogical by XRD and chemical (major and trace elements) by ICP-MS and XRF methods. The sediments of the veredas were still dated by radiocarbon method using the AMS (Accelerator Mass Spectrometry) technique, and also submitted to palynological analyses including the counting of charred particles. The regoliths of the studied area vary of sandy to silty sand textures being composed by quartz and kaolinite, and in minor amounts by muscovite, sillimanite, goethite, microcline and albite. The high values of SiO2 confirm the quartzose character of these regoliths, while the values of Al2O3, more expressive in the saprolite and in the sediments from veredas reflect the higher participation of the kaolinite, which is the single clay mineral identified in these samples. The mineralogical and chemical compositions of these materials indicate provenience of metamorphic rocks and laterites that faced with warm and wet climatic conditions have been suffered strong chemical weathering and leaching. The formation and wide development of vereda of Mauritia flexuosa since about 1550 years BP as showed by the pollen analyses corroborate the humidity increase in the area, which also favored the expansion of forests. In fact, trees of Virola, Alchornea, Melastomataceae and Moraceae among other were frequent suggesting that gallery forests as well as patches of secondary forests indicated by Didymopanax, Cecropia and Attalea occurred in this region in the most of the recorded period. In spite of those humid conditions, there are records of reduction of the forests about 1400-1100 years ( FC), 900-200 years (AM and FC) and between 700 and 300 years (site TIA) in favor of the expansion of the savannas. It is probable that the reduction of forests during those periods has been provoked by the increase in the intensity of fires, inferred by the highest concentration of charred particles in the sediments, prior and during the forest cover decrease. These fires are still common in the area, being more frequent in the neighborhoods of human establishments (indigenous) and cattle farms where they possibly work as a barrier to forest expansion. Although, alternate hydromorphic and hydrological stress conditions also contribute to prevent a forest expansion. The granulometrical, mineralogical and geochemical characteristics of the regolith cover combined to the sediments pollen and ages records allowed to interpret that the studied savanna-forest landscape, which is currently marked by a complex mosaic of grassy and woody savanna crossed by veredas of Mauritia flexuosa, gallery forest corridors and islands of forest covering sandy, quartzose and kaolinitic regoliths agree with the modern warm and wet climate conditions prevailing in this region since the Late Holocene. In compensation, features such as stone lines composed by fragments of quartz and crusts denote erosive events occurred probably in the Late Pleistocene and even in the Medium Holocene when dry to arid climates dominated the region. Then, the regarded landscape has been a stage of intense ecological and geomorphological transformations fomented mainly by the climatic changes imposed to the area, although the prehistoric and the modern man has also contributed, in the sense of delaying the expansion of the forests on the savannas.