Navegando por Assunto "Itaituba - PA"

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Análise tafonômica de Eremotherim laurillardi (Lund, 1842) dos depósitos pleistocenos, município de Itaituba, Pará
(Universidade Federal do Pará, 2008-08-18) FERREIRA, Denys José Xavier; RAMOS, Maria Inês Feijó; http://lattes.cnpq.br/4546620118003936
The present work deals with the taphonomic study of Eremotherium laurillardi (Lund, 1842), a ground sloth found within a Pleistocene depositional site in Itaituba town, State of Pará. The samples comprise approximately eight hundred skeletal fragments and complete pieces of this specie deposited in the Paleontological Collection of Museu Paraense Emílio Goeldi. Taphonomy is the post mortem history of fossils, the study of processes that influence preservation of potential fossils. It consists of two major aspects: biostratinomy, the study of processes affecting organism remains prior to burial and fossil diagenesis affecting potential fossils after burial. The biostratinomic study showed that the skeletal remains had a loose packing and were poorly sorted, indicating deposition in situ. Moreover, the biostratinomic study revealed that the taxonomic composition of the skeletal fragments is monotypical and monospecific related to catastrophic death (non-selective) by abrupt burial which occurred before necrolysis. Traces of abrasion and reworking during transport of the skeletal remains are insignificant and/or non-existent. Bioerosion facies have not been identified too. The non-preservation of soft parts shows that the necrolysis occurred in an aerobic environment. However, the partial presence of pyrite in the foramina and channels of ribs and teeth analyzed point to localized reducing micro environment. The skeletal remains show their morphological structures, both external and internal, well preserved suggesting that they were not exposed to the exogenous cycle, due to the quick burial. The fossildiagenetic study, conducted on samples of ribs, teeth and vertebrae, using both optical and scanning electron microscopy, revealed that both the bone and dental structures, known as Havers` channels and dentinal tubules, respectively, remained well – preserved. Additionally EDS Analysis (Energy Dispersive Spectroscopy) carried out on these components showed a nearly unaltered chemical composition relating to Ca, P, Mg, K and Na contents.
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Aspectos clínicos e a prevalência de doenças infecto-parasitárias juntamente com a exposição ao mercúrio metálico em duas comunidades garimpeiras na Amazônia
(Universidade Federal do Pará, 2006) MIRANDA, Antonio Marcos Mota; VIEIRA, José Luiz Fernandes; http://lattes.cnpq.br/2739079559531098
The evaluation of the health conditions in two “goldwashers” communities in the Amazon region, goldmines of São Chico and Creporizinho, it was verified the prevalence of clinical and neurological symptoms and the parasitic occurrence of infectious illness, associate to the concentration of total mercury in the urine of the “goldwashers”. At the São Chico, 104 “goldwashers” were investigated, while as Creporizinho 169, it was used the socio economic, epidemiological and laboratorial condition as diagnostic methodologycal and it was used sentable statistical tests for significance verification. The results demonstrated that the average of the metal in “goldwashers” urine of Sao Chico is superior to those of Creporizinho 9.29 μg creatinina Hg/g and 5.64 μg creatinina Hg/g, respectively. Where the distribution of Hg in urine of the São Chico and of the Creporizinho population, below 93% - 96% of the IBMP and above 7%-4%, respectively. There is predominance of the masculine sex in both miners and the occurrence of STD’s in the two goldminers, whose sequence was identical, where the intestinal parasitism and malaria are themost prevalent, however both are below of the IBMP. The clinical evaluation of São Chico presents prevalence of to osteomuscular, dermatological and digestive 32%, 30% and 23% symptoms, respectively. While in the Creporizinho occurred change in the sequence to osteomuscular, digestive and dermatological 51%, 44% and 39%, respectively. Amongst the most prevalent neurological symptoms the tremors, parestesias and chronic headache were present in the group of São Chico and Creporizinho the following sequence, respectively, 38% - 58%, 32% - 53% and 28% - 48%. The health conditions are more precarious in São Chico miner, than Creporizinho however the “goldwashers” are occupationally injured in the two studied populations, nevertheless there are not safe parameters to affirm the presence of the chronic mercurial illness, taking into consideration the variable analyzed in this study.
Acesso aberto (Open Access)
Avaliação da contaminação mercurial mediante análise do teor de Hg total em amostras de cabelo em comunidades ribeirinhas do Tapajós, Pará, Brasil
(2000-04) PINHEIRO, Maria da Conceição Nascimento; GUIMARÃES, Geraldo de Assis; NAKANISHI, Junko; OIKAWA, Teiichi; VIEIRA, José Luiz Fernandes; QUARESMA, Manoel; CARDOSO, Bernardo da Silva; AMORAS, Walter Wanderley
This study evaluates human exposure to methylmercury in fishermen and their families in four villages on the Tapajós river: Rainha, Barreiras, São Luís do Tapajós and Paraná-Mirim. Hair analyses were performed with atomic absorption spectophotometry. Total hair mercury levels varied between 2.9mg/g and 71.5mg/g. Paraná-Mirim showed the lowest level. The highest level was found in São Luís do Tapajós and Barreiras. The hair mercury was six to seven times higher than the established safe limit of 10mg/g. No statistically significant difference was found between the mean level of total mercury taken from the inhabitants living downstream and upstream in Itaituba village (p > 0.05). These results confirm that human exposure to methylmercury is occurring on the Tapajós river and suggest that continued fish ingestion in that region is a potential risk factor for the appearance of symptoms and signs of Minamata disease. An immediate epidemiological survey program is recommended.
Acesso aberto (Open Access)
Avaliação temporal da exposição humana ao mercúrio no Oeste paraense
(Universidade Federal do Pará, 2015-11-27) ANDRADE, Paulo Douglas de Oliveira; SOUZA, Givago da Silva; http://lattes.cnpq.br/5705421011644718
In the present study we described mercury (Hg) exposure evolution in two riverside communities of Tapajos River Basin, Brazilian Amazon. These communities are exposed to this metal by the consumption of fishes that they fishing from the contaminated river. The contamination is due to a process that occurs mainly due to the weathering of soil in the area (which is naturally rich in Hg) and gold mining, that uses mercury to isolate the gold. The analysis used a dosimetric database containing values of mercury, wich was generated from hair samples of the riversides from Tapajos. The data collection was conducted for 17 years (1998-2014) and totaled 1.502 (one thousand, five hundred two) samples, which were divided into four groups: adult male, adult female, male child and female child. The results reveled the group with the highest risk of exposure: the adults males. After all the years of study, the adult male group was the group with the highest average Hg levels (14,41 μg/g ± 10 μg/g). On the other hand, all groups showed a trendy to decrease these levels, with the men took more time to start this process of reduction rates. Their levels dropped from 16,61 μg/g in 2007 to 11,23 μg/g in 2013. Women's group reduced from 13,92 μg/g in 2004 to 7,04 μg/g in 2013. Children had more significant reduction, wherein the girls dropped from 15.42 μg/g in 2001 to 3.83 μg/g in 2014, and the boys from 12.96 μg/g to 5.95 μg/g in the same years. The problematic situation involving the adult male group may indicate a more traditional lifestyle (based on a high fish consumption), less contact with professionals and researchers who instruct the population about the risks of poisoning, and more restrict nutrition, without red meat, tropical fruits, etc. In this sense, it is evident the need for greater awareness of this group in particular (adults males), and must the public health policies aimed specifically, must be enhanced in the region.
Acesso aberto (Open Access)
Contexto geológico, estudos isotópicos (C, O e Pb) e associação metálica do depósito aurífero Tocantinzinho, domínio Tapajós, Província Tapajós-Parima
(2013-03) VILLAS, Raimundo Netuno Nobre; SANTIAGO, Érika Suellen Barbosa; CASTILHO, Marília Portela
The Tocantinzinho ore deposit is located along a NW–SE-trending lineament, southwestern of Itaituba (Pará, Brazil), and is the largest known gold deposit of the Tapajós Province. The host Tocantinzinho granite is essentially isotropic and dominated by syenogranites and monzogranites that have been weakly to moderately altered by hydrothermal fluids. Microclinization (earliest), chloritization, sericitization, silicification and carbonatization (latest) are the main types of alteration. Most mineralization was contemporaneous with the sericitization/silicification and is represented by sulfide- and gold-bearing veinlets which locally occur as stockwork. Pyrite, chalcopyrite, sphalerite and galena are the most common sulfides. Among the ore metals, Cu, Pb and Zn present the highest contents, but Mo, As and Bi locally show anomalous concentrations. The relationship of Au with Cu, Pb or Zn is at random and the Au/Ag ratios range from 0.05 to 0.5. The higher the sulfide contents, the higher the Au concentrations, though it occurs mainly included in pyrite. Zircon monocrystals from the Tocantinzinho granite yielded an average Pb-Pb age of 1982 ± 8 Ma and may represent an earlier event of the Creporizão magmatic arc. δ13CPDB values for calcite from the carbonatization stage fall dominantly between -3.45 and -2.29‰, being compatible with a deep crustal source that may include carbonatite reservoirs. In turn, δ18OSMOW values vary from +5.97 to +14.10‰, being indicative of magmatic derivation, although the less positive values suggest contribution from surficial waters. Unpublished fluid inclusion study reveals the presence of aquo-carbonic fluids, whose CO2 could have been dissolved in the granitic magma rather than being related to the shear zone. The available data allow the Tocantinzinho deposit to be classified as a granite-hosted, intrusion-related gold deposit.
Acesso aberto (Open Access)
Diversidade beta entre taxocenoses de serpentes na margem direita do rio Amazonas, enfocando a história natural das serpentes do Parque Nacional (PARNA) da Amazônia, Pará, Brasil
(Universidade Federal do Pará, 2012) FROTA, Jossehan Galúcio da; COSTA, Maria Cristina dos Santos; http://lattes.cnpq.br/1580962389416378; PRUDENTE, Ana Lúcia da Costa; http://lattes.cnpq.br/1008924786363328
Acesso aberto (Open Access)
Estado nutricional de populações expostas ao mercúrio: estudo observacional de coorte nas regiões do rio Tapajós e Tucuruí
(Universidade Federal do Pará, 2017-06-19) MACHADO, Camila Lorena Rodrigues; LÓPEZ, Maria Elena Crespo; http://lattes.cnpq.br/9900144256348265
The riverside communities of the Amazon are vulnerable populations exposed to factors that are difficult to find in the populations of the rest of the country (from the bioavailability of Amazonian natural wealth to geographic isolation). However, little is known about the anthropometric characteristics and eating habits of these communities. The objective of this study was to conduct a study of the nutritional status and dietary intake of riparian communities in the Tapajós and Tucuruí regions, through the analysis of anthropometric parameters (Body Mass Index, Waist Circumference, Waist-Hip Ratio and Neck Circumference) , As well as food profile analysis. A total of 234 adult subjects were included in this study (143 from Tapajós and 91 from Tucuruí). The results showed that 77% and 65% of the Tapajós and Tucuruí populations, respectively, present 2 or more altered anthropometric parameters, showing the predominance of pre-obesity and obesity in these populations. Women had a higher risk of developing obesity-related diseases. The consumption of fruits in the Tapajós region (87.3%) and in the Tucuruí region (89%), as well as the consumption of fish (Tapajós 97.9% and Tucuruí 95.6%), And flour (Tapajos 86.6% and Tucuruí 86.8%). We also observed that the populations present healthy eating habits, but consume certain foods that would be influencing the current nutritional status, as well as the way of preparation. Studies that include these populations are scarce, and educational and public health measures are necessary to raise awareness of the improvement of eating habits, the importance of practicing physical activity, and to avoid behaviors such as Consumption of alcohol and smoking to avoid problems related to obesity.
Acesso aberto (Open Access)
Granitos pórfiros da região de vila Riozinho, província aurífera do Tapajós: petrografia e geocronologia
(2008-09) LAMARÃO, Cláudio Nery; SOUZA, Kleber Silva de; DALL'AGNOL, Roberto; GALARZA TORO, Marco Antônio
The Tapajós Gold Province (TGP) is located in the center of the Amazonian craton. It is dominated by Paleoproterozoic calc-alkaline and A-type granitoids and intermediate to felsic volcanic sequences. The Vila Riozinho region, situated in the central-eastern part of the TGP and constituted by the Vila Riozinho, Moraes Almeida and Jardim do Ouro villages, has the more important geologic units that characterize this province. The aim of this paper is to present new petrographic and geochronological data on the porphyry granites associated with the dominant monzogranitic rocks of the Older São Jorge granite and with ignimbrites and rhyolites of the Moraes Almeida Formation and leucogranitic rocks of the Maloquinha suite. The geochronological data revealed at least two distinct periods of generation of porphyry granites in the region. The first, associated with 1.98 Ga calc-alkaline magmatismo, and the second with 1.88 Ga alkaline rocks. Backscattered images and analyses of EDS (energy dispersive spectrometry) obtained with a SEM (scanning electron microscope) showed that is frequent the occurrences of gold particles in the porphyry granites filling cavities in quartz and plagioclase, or associated with epidote and alkali feldspar. These data suggest that the porphyry granites can have contributed to gold mineralization of the Vila Riozinho region, and shows that detailed studies are necessary to elucidate metallogenetic importance of these rocks in the gold mineralization of the region.
Acesso aberto (Open Access)
Haplologia no falar paraense
(Universidade Federal do Pará, 2013-04-23) PAZ, Flávia Helena da Silva; OLIVEIRA, Marilucia Barros de; http://lattes.cnpq.br/9728768970430501
The objective of this paper is to show the phenomenon of spontaneous speech in Haplologia citizens Pará. The study refers more specifically to what we call Haplologia between sentences. Evaluates the contexts of sentences composed only of d/ - /d/, /t/ - /d/,/t/ - /t/ and /d/ - /t/, exemplified respectively by: la(du) dʒi fora, per(tu) du, a gen(t∫i) t∫inha medu e tu(du) t∫inha. The factors evaluated are divided into two groups: linguistic and extralinguistic aiming to show the circumstances favorable and unfavorable to the application of the phenomenon under study. Groups of linguistic factors are: Relationship between palatalization and haplologia; Quality of vowels; class elided syllable word; Tonicity of neighboring syllables, and syllabic structure;. With regard to extralinguistic factors, we analyzed: Sex. Age and schooling, following the stratification proposed in the project Linguistic Atlas of Pará (ALIPA). The data analyzed comprise the corpus of two cities Pará Belém, capital of Pará, and Itaituba, Pará city which is 891 km from the capital mentioned. Data collection followed the guidance of Sociolinguistics Variationist. The data were submitted to the program variable rule VARBRUL. The results indicate the haplologia as variable rule, however, the phenomenon is few productive among informants the two cities. In the assumptions of Sociolinguistics Variationist (Labov, 2008) palatalization, the increasing height of the vowel and consonantal deconstruction of the group can be considered a process of embedding, while the phonetically-phonological rules would be considered the feeder haplologia (BISOL,1996).
Acesso aberto (Open Access)
Hormônios tireoidianos, anti-TPO e concentrações de mercúrio total na avaliação da disfunção glandular em população ribeirinha da Amazônia
(Universidade Federal do Pará, 2015) OIKAWA, Teiichi; PINHEIRO, Maria da Conceição Nascimento; http://lattes.cnpq.br/6353829454533268
There is evidence that mercury accumulation in the thyroid can cause endocrine and immune disorders. Riverside populations of the Amazon with a history of prolonged exposure to mercury have been investigated for neurological damage, but little is known about the hormonal disorders and specific immune thyroid. The objective of this study is to verify the existence of association between the total mercury concentrations in hair samples and concentrations of thyroid hormones and the anti-TPO antibody. The study included 86 riverine from Tapajos region mercury exposed to long-term. Participated this study men and women aged between 14 and 54 years, residents in place for more than five years. Measurements of serum hormone concentrations (TSH, T3 and free T4) and Anti-TPO titles were taken by enzyme immunoassay. Total mercury (THg) in hair samples was measured by atomic absorption spectrophotometry by cold vapor technique. Hormonal dysfunction occurred in 10.3% with an increase of T3, 2.3% with a reduction of T4L, 3.4% decrease in TSH and 4.6% with increased TSH expressed that the maximum value of 8.9 μU/m. Anti-TPO titles were normal in all participants. There was no correlation of hormonal markers (TSH, T3 and T4L) or the Anti-TPO with mercury levels. The results showed that THg concentrations in hair, serum TSH and anti-TPO titles were not influenced by sex; that hormonal changes in thyroid studied riparian not associated with the levels of THg suggesting the interference of protector factors on thyroid function.
Acesso aberto (Open Access)
Influência da atividade garimpeira na dinâmica urbana das cidades amazônicas: o caso de Itaituba/PA
(Universidade Federal do Pará, 2013-11-29) SCHUBER, Eliana Souza Machado; ROCHA, Gilberto de Miranda; MORAES, Sérgio Cardoso de; http://lattes.cnpq.br/4568311568729454
This research aims to analyze the influence of mining activity on the formation of urban space of the city of Itaituba/PA, which has a strategic location on the wealthy Tapajós Gold Province. It is considered that the mining activity in this region is specific and structured differently than traditional extraction (latex) from installation manual mines to the insertion of large machines, which currently occurs in the mines. Part of the hypothesis is that the oscillations of this activity intertwined with government interventionist actions dictated the pace of urban dynamics Itaituba. It begins with a comprehensive analysis of the process of urbanization of the Amazon, involving the exploitation of natural resources, particularly minerals and exploitation of gold. Then we develop a periodization of gold mining in the Tapajos Gold Province, from the 60s, establishing the main periods and sub-periods that influenced in some way in the urban dynamics of the city. Then we developed an overview of spatial and urban consequent repercussions mining activity in Itaituba. The research also considered the urban processes that are focusing on the city from the perspective of implementation of large energy and logistics (port) projects in the region.
Acesso aberto (Open Access)
Metilmercúrio e mercúrio inorgânico em peixes comercializados nos mercado municipal de Itaituba (Tapajós) e mercado do Ver-o-peso (Belém)
(Universidade Federal do Pará, 2011-12-12) ARRIFANO, Gabriela de Paula Fonseca; CRESPO LÓPEZ, Maria Elena; http://lattes.cnpq.br/9900144256348265
Mercury is a dangerous metal and an important source of environmental contamination in Brazil and particularly in the Amazon. The main target organ of this metal is the CNS where it causes damage that can lead to classic symptoms: ataxia, paresthesia, dysarthria, and changes in the developing nervous system of children. The mercury contamination in the Amazonian rivers increases the amount found in fish, especially those at the top of the food chain, exposing people to mercury poisoning the rivers, since the fish is a central element in the diet of these populations. Therefore, it is essential periodic monitoring of mercury levels in fish species consumed in the region. Our study proposes to identify the levels of methylmercury and inorganic mercury in fish species consumed by the riverside populations of the Tapajós region and compare them with the levels found in the same species obtained in the region of Belém also perform a comparison with results obtained by Dos Santos et al. (2000) and analyzing the current level and the old. Fish were collected in the municipal market Itaituba, Tapajós, and market the Ver-o-Peso in Belém. Muscle samples of each fish were dried and analyzed by the Universidad de Castilla-La Mancha (Spain) for quantification of methylmercury and inorganic mercury. The results obtained in this study showed that only piscivorous fish from the Tapajós region have levels of methylmercury above the limit recommended by WHO (0.5 μg / g). All in all study groups, levels of inorganic mercury are well below this limit. The species was the most contaminated Brachyplatystoma flavicans (Dourada) and even to exceed five times the WHO limit of tolerance. With our data, we can say that the fish of the Tapajós region are still currently exposed to high concentrations of mercury. The non-fish-eating species had low concentrations of organic mercury, is fit for human consumption. This study supports the importance of continued monitoring of the environments considered exposed and not exposed in the Amazon. Knowledge originated by this monitoring definitely foster the development of prevention strategies and government actions before the problem of mercury contamination in the Amazon. Keywords: inorganic mercury, methylmercury, fish, Tapajós, Belém
Acesso aberto (Open Access)
Parasitoses intestinais e desnutrição em crianças expostas ao mercúrio na Amazônia
(Universidade Federal do Pará, 2003) XAVIER, Fábio Branches; SILVEIRA, Luiz Carlos de Lima; http://lattes.cnpq.br/9383834641490219
The study show the prevalence of intestinal parasitosis, malnutrition and mercury exposure in childish population of Barreiras riverside community, Itaituba district: western of Pará state. To detect intestinal parasitosis in excrement was used Hoffmann Method. For diagnosis of malnutrition admit the recommended method by World Health Organization (WHO). The proportion of total mercury in specimen hair was obtained to Atomic Spectrofotometry Absorption. The results showed incrase of prevalence of Ascarís fumbrícoídes and Ancylostoma duodenafe. Malnutrition acute cases to total 2,4% of population. Children with high levels of total mercury come down to 43,5%. Did not exist relation between intestinal parasitosis and malnutrition.
Acesso aberto (Open Access)
Petrografia, química mineral e processos hidrotermais associados ao depósito de ouro São Jorge, Província Aurífera do Tapajós, Cráton Amazônico
(2009-06) BORGES, Régis Munhoz Krás; DALL'AGNOL, Roberto; LAMARÃO, Cláudio Nery; FIGUEIREDO, Marco Aurélio Benevides Maia; LEITE, Albano Antônio da Silva; BARROS, Carlos Eduardo de Mesquita; COSTI, Hilton Túlio
The Paleoproterozoic São Jorge gold deposit is situated in the Tapajós Gold Province of the Amazonian Craton. The deposit is hosted by an amphibole biotite monzogranite, composed of quartz, potassic feldspar, plagioclase, amphibole, biotite, titanite and opaques. Four dominant mineral assemblages were recognized in the deposit. Assemblage 1 was formed during the magmatic stage and is characterized by the presence of amphibole and andesine-oligoclase. Assemblage 2 shows the total replacement of the amphibole and intense saussuritization of the primary plagioclase, epidote is a ubiquitous phase and biotite is partially chloritized. Assemblages 3 and 4 are related to the hydrothermal processes, which generated the sulfide and gold mineralization. Assemblage 3 is dominated by chlorite and albitic plagioclase with subordinate white micas and, sometimes, biotite. Assemblage 4 is dominated by white micas, carbonates and pyrite. It is a result of a phyllic alteration, with associated carbonatization. Chlorite geothermometer suggests temperatures of 300±40 °C for the 3 and 4 assemblages. Al in hornblende geobarometer indicates low pressures, around 1 kbar for the crystallization of the mineralized granites. Oxidizing conditions, above NNO, prevailed during the genesis of the deposit. The hydrothermal assemblages of São Jorge differ from those described at Joel and Davi and are not dominated by epidote minerals as registered in other areas of the Tapajós province. A porphyry model or intrusion-related model are best adapted for the São Jorge deposit. The latter has similarities with the Serrinha deposit in the Juruena province and Batalha in the Tapajós province but it has more strong analogies with the Volta Grande hydrothermal system in southern Brazil.
Acesso aberto (Open Access)
Representações sociais da pesquisa do mercúrio em uma comunidade ribeirinha do Tapajós
(Universidade Federal do Pará, 2010) LIMA, Maria de Nazaré Alves de; NASCIMENTO, Ivany Pinto; http://lattes.cnpq.br/6649004854958284; PINHEIRO, Maria da Conceição Nascimento; http://lattes.cnpq.br/6353829454533268
This study proposes to examine the social representations of the residents of a community on the banks of the Tapajós River in the city of Itaituba- Pará, how to research on mercury in that area conducted by various institutions. The theoretical approach was the procedural approach of social representations developed by Serge Moscovici. We sought to delineate the understandings of these residents through content analysis of Bardin, making an analysis of quantitative and qualitative data to investigate the discourses of social actors. Graphs were prepared containing the percentages of these concepts to analyze the data more relevant. In the end, it was observed that the respondents are in favor of searches that take place there as an expectation of being discovered and met their needs, believing in the existence of mercury in the Tapajós River and the associated mining activity although we have identified speeches that confuse the metal with the planet Mercury or antiseptic. These perceptions are linked to their experiences and conversations of their peers and suggesting the need for a continuous information service, organized by the community and with the support of researchers for training and training of community leaders for advice, counseling and self-protection that community about the issue and the research of mercury.
Acesso aberto (Open Access)
A sucessão siliciclástica-carbonática neocarbonífera da bacia do Amazonas, regiões de Monte Alegre e Itaituba (PA)
(Universidade Federal do Pará, 2010-03-14) LIMA, Hozerlan Pereira; NOGUEIRA, Afonso César Rodrigues; http://lattes.cnpq.br/8867836268820998
Neocaboniferous deposits of Morrowanian age in the Amazon Basin, northern Brazil, characterize the transition zone between Monte Alegre (siliciclastic rocks) and Itaituba (carbonate rocks) formations. The outcrop-based facies and stratigraphic analyses of this up to 40m thick succession, exposed in the Monte Alegre and Itaituba regions, State of Pará, allowed the recognition of five facies associations (FA), representative of a transitional desertic to coastal system, comprising: eolian dune/interdune (FA1), sandy sheet/wadi (FA2), lagoon/washover (FA3), beach/tidal flat (FA4) and lagoon/tidal delta (FA5). FA1 contains bimodal fine to medium-grained sandstone with medium-scale trough cross-stratification, subcritically climbing translatent stratification and inversely graded lamination (dune deposits). Massive fine sandstones with root marks suggest development of paleosols, while adhesion warts indicate eolian grain migration on wet interdune surface. FA2 comprises fine to medium-grained sandstone with even-parallel stratification and subcritically climbing translatent stratification, related to deflation, while fine to medium-grained sandstone with tangential and recumbent-folded cross-stratification and convolute bedding suggest migration of high-energy ephemeral rivers. FA3 with laminated mudstone and fine-grained sandstone with climbing-ripple cross lamination, hosting the ichnofossil Palaeophycus, suggests a low-energy environment of lagunar/washover type. FA4 is characterized by fine to medium-grained sandstones with planar and low-angle cross-stratification, interbedded with lenticular dolomite, locally truncated by fine to medium-grained sandstones. These facies correspond to the zone of swash and backwash on beach environment, locally cut by small channels, while the carbonate is interpreted as precipitated in ponds. FA 4 also comprehends mudstones with mudcracks and mud curls as well as small to medium-scale planar cross-bedded sandstones with mud drapes lining foresets and reactivation surfaces, suggesting migration of sandwaves in intertidal zones. FA5 is represented by dolomitized limestones (mudstones, wackestones, packstones and grainstones) containing vuggy and moldic porosities. Bioclasts include brachiopods, echinoderms, foraminifers, ostracodes, bryozoans, trilobites, mollusks and non-fragmented corals, and furthermore the trace fossil Thalassinoides. Additionally, this facies association comprises conglomerates with pebbles of dolomitized limestones, fine-grained sandstones with low-angle cross-stratification and reactivation surfaces, locally overlaid by fine sandstones with sigmoidal cross-stratification and climbing cross-lamination, which were interpreted as tidal inlet and tidal delta deposits. The facies/microfacies associations and paleontological data presented here point to a lagoonal environment, connected in part to a coastal desert zone, and characterize the transition between Monte Alegre and Itaituba formations. The abundance of fine sands with rounded grains in carbonate facies is consistent with siliciclastic influx from the desert adjacent to coastal environment. Warm tropical conditions for the environments can be inferred from the limestones and their diverse fauna as well as from the clay minerals, principally smectite. The interbedding of siliciclastic and carbonate rocks which characterizes the end of the deposition of the Monte Alegre Formation and the beginning of the sedimentation of the Itaituba Formation justifies a unique system representation for this interval.
Acesso aberto (Open Access)
Termocronologia por traços de fissão em apatita da Borba Sul da Bacia do Amazonas, na região de Itaituba (PA)
(Universidade Federal do Pará, 2010-11-09) PINA, Aline Carla Miranda de; LELARGE, Maria Lidia Vignol; http://lattes.cnpq.br/3165548495925769; MOURA, Candido Augusto Veloso; http://lattes.cnpq.br/1035254156384979
The region of Itaituba (PA) located at the South portion of the sedimentary basin of the Amazon can be defined as a border zone between this basin and the Amazonian Craton. In this region outcrop sedimentary rocks, belonging to Pitinga, Maecuru, Ererê, Barreirinha, Curiri, Monte Alegre and Itaituba Formations, representatives of sineclise phase sedimentary basin of the Amazon; sedimentary rocks the stage rift gathered in Prosperança Formation; besides igneous rocks of Iriri Group, Parauari Intrusive Suite and Maloquinha Intrusive Suite, which compose the basement of the sedimentary basin. The fission track thermochronology of apatite was used in the investigation of thermotectonic evolution of the sedimentary basin of the Amazon region of Itaituba (PA), mainly from the dating of basement rocks of the basin. The method of fission tracks in apatite is a marker thermochronologic low temperature, recording temperatures of up to 120 º C. When subjected to conditions of temperatures above the traces of apatite fission are cleared, resetting the clock geochronological for this method, and registers, thus, a new event. Thus, this tool was used to investigate the age of the tectonic processes that affected the Amazon Basin, which were also recorded in the rocks of its basement. Given the scarcity of apatite in sedimentary rocks sampled units of the Amazon basin, only a sample of the Monte Alegre Formation sandstone has been dated by fission track method. However, in the basement could be dated 20 samples, representing various rocks including rhyolites, granites and olivine-diabase of Paleoproterozoic, belonging to the three units mentioned above. The sandstone of the Monte Alegre Formation, whose age of the lithostratigraphy and Mesocarbonífero, provided apparent ages in apatite fission track AFT) from 91 Ma. Statistically this sample revealed the existence of two populations of apatite grains: a population with a mean age of 105 Ma and another population with a mean age of 64 Ma, indicating that this sample was subjected to two events thermotectonic. This fact can be confirmed through the thermal modeling also showed that the presence of two events whose ages are 106 Ma and 58 Ma. Samples of the basement were divided into three groups according to ages TFA obtained and the results of mathematical models. In group 1 TFA ages ranged from 163.0 Ma and 258.7 Ma, for group 2 ages were established between 142.1 Ma and 147.4 Ma, while samples of group 3 were between 170.1 Ma and 180.9 Ma is noteworthy that the ages of crystallization of igneous bodies sampled are between 1.8 and 1.9 Ga. The mathematical modeling of samples of groups 1 and 2 record the same epsódios, a first cooling, followed by heating and finally an episode of cooling. This last cooling event occurred about 100 Ma for all samples of these groups, except the sample IT-16 passing through the final event of cooling for 62 Ma. The thermal histories of samples IT-22 and 23 show a period of accelerated cooling compared to previous samples, their thermal histories ending at 39 Ma and 35 Ma, respectively, suggesting the existence of neotectonic events in the region. The events of approximately 100 Ma recorded in the Monte Alegre Formation sandstone and models of the samples of the basement can be related to a compressional tectonics that occurred according to the opening of the eastern equatorial Atlantic and the convergent movement of Andean subduction zone, west of South American plate. In turn the events of Tertiary age (64-58 Ma) marked these rocks may show reflections of a process where dextral transform interacted plates South American, Caribean and Nazca, reactivating old fracture zones. The various ages obtained for samples of the basement (ranging from 142.1 Ma and 258.60 Ma) are markers of major tectonic events, but may be registering the different ages at which these samples passed by the isotherm of 120 ° C, indicating thus the occurrence of a tectonic with different behavior in different areas of this region.
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The Tocantinzinho gold deposit, Tapajós province, state of Pará: host granite, hydrothermal alteration and mineral chemistry
(2013-03) SANTIAGO, Érika Suellen Barbosa; VILLAS, Raimundo Netuno Nobre; OCAMPO, Ruperto Castro
This paper presents geological, petrographic and mineralogical data about the granite that hosts the Tocantinzinho gold deposit and aimed at contributing to the understanding of the hydrothermal processes related to the ore genesis. The host granite is a late to post-tectonic biotite monzogranite that fits in the oxidized sub-type of the ilmenite series. It was emplaced at depths of 6 - 9 km and reveals no deformation other than fracturing and brecciation. This intrusion has undergone mild to moderate hydrothermal alteration that generated two main rock varieties (salami and smoky), with no significant mineralogical or chemical differences, though quite distinct macroscopically. Several types of hydrothermal alteration have been recognized in the granitic rocks, greatly represented by filling veins and/or replacement of primary minerals. The hydrothermal history started with microclinization, during which the granitic protolith was in part transformed into the salami variety. This process was followed by chloritization when the temperature dropped to ~330 ºC producing chamosite with XFe in the 0.55 - 0.70 range. Then it evolved to sericitization, at the same time that ore-bearing fluids precipitated pyrite, chalcopyrite, sphalerite, galena and gold. As alteration advanced, solutions saturated in silica and formed quartz veinlets. At the latest stage (carbonatization), aqueous and aqueous-carbonic fluids might have mixed, allowing Ca2+ e CO2 to react to form calcite. Most sulfides are present in veinlets that crosscut the granite, some arranged as stockwork. Gold is normally very fine-grained and occurs mainly as submicroscopic inclusions or along microfractures in pyrite and quartz. The Tocantinzinho deposit is very similar to the Batalha, Palito and São Jorge deposits, and to those of the Cuiú-Cuiú goldfield. Topologically, it has been classed as an intrusion-related gold deposit.
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Uso de recursos naturais por comunidades ribeirinhas amazônicas: bases para as políticas de concessões florestais
(2013-06) MELO JÚNIOR, Luiz Cláudio Moreira; TOURINHO, Manoel Malheiros; SAYAGO, Doris Aleida Villamizar; PALHA, Maria das Dores Correia
This article deals with the relations between agrarian communities, natural resources, local knowledge and practices around the areas destined to forest concession processes along Mamuru and Arapiuns rivers, state of Pará. For primary data collection, questionnaires were filled with the population of these localities. Maps of natural resource use were constructed for each community studied, from the multiple uses of resources by communities. As a main conclusion the study indicates that a major challenge is that the policies of forest concession consider the areas of the communities as spaces for reproduction of the community social systems as well as collective use of natural resources. Otherwise, may suffer a strong anthropogenic pressure due to the attractive possibilities of use of natural resources for commercial and industrial purposes.
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Vulnerabilidade socioambiental em área peri-urbana suscetível a movimentos de massa: estudo de caso no Distrito de Miritituba, Itaituba, Pará.
(Universidade Federal do Pará, 2018-05-21) SENA, Marson Menezes; RODRIGUES, Hernani José Brazão; http://lattes.cnpq.br/1660618871530248
Natural Disasters associated with mass movements have increased considerably in the last decades, causing a series of physical damages, with consequences mainly on human life, private, public and collective goods. Differently from other regions of Brazil, the Amazon region, despite of the predominance of lowland areas, also suffers from mass movement events caused mainly by the performance of atmospheric rainfall systems that when in excess, produce events of this nature. The objective of this work was to analyze the socioenvironmental consequences of urban occupation in areas of risk of landslides, starting from a case study in the district of Buritizal, District of Miritituba, Itaituba / PA and presenting administrative solutions through elaboration and proposition of a bill in the Itaituba City Council that aims to reserve housing through the National Popular Housing Program for families who have lost their homes or live in areas on the risk of natural disasters. The present study was carried out based on two lines of research, one of bibliographic and the other of field, with mixed approach (quantitative and qualitative), in order to show the problem in the studied context. So, socioeconomic indicators were used from the e-SUS questionnaires, such as, from secondary data obtained from the IBGE, to the municipality of Itaituba and CPRM. The means of social vulnerability were related to the means of environmental vulnerability. From the described scenarios, it was possible to verify that the scenario referring to social variables showed 90% of average vulnerability. On the other hand, the scenario regarding environmental vulnerability was the most critical, with more than 75% of high vulnerability. Summarize, it is verified that both the variables that make the social indicators and the environmental factors have been determinant on the definition of the socio-environmental vulnerability scenario. Socio-environmental vulnerability reached 2.7, so the socioenvironmental vulnerability of families living in the neighborhood of Buritizal was defined as high. The Socio-environmental Vulnerability allowed to observe and quantify the different levels of vulnerability experienced by each family surveyed, and it is possible to indicate which families have more or less vulnerability residing in the neighborhood of Buritizal.