998 resultados para chlorite
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Petrografia, suscetibilidade magntica e geoqumica do Granito Rio Branco, Provncia Carajs, sudeste do Par, Brazil. O Granito Rio Branco um stock paleoproterozoico intrusivo no biotita-monzogranito arqueano Cruzado. Ocorre a oeste da cidade de Cana dos Carajs, nas proximidades da mina de cobre do Sossego na Provncia Carajs. constitudo por sienogranitos no deformados e isotrpicos, hololeucocrticos, em geral de granulao mdia. A mineralogia formada por feldspato alcalino perttico, quartzo e plagioclsio. A biotita, intensamente cloritizada, a principal fase mfica, acompanhada por flluorita, allanita, zirco, pirita e calcopirita como minerais acessrios. Albitizao e, com menor intensidade greisenizao, afetaram o granito, sendo a mineralogia secundria albita, fluorita, topzio, clorita, muscovita, siderofilita e xidos e/ou hidrxidos de ferro. O Granito Rio Branco apresenta valores sistematicamente baixos de suscetibilidade magntica (SM) variando de 1,3 x 10<sup>-5</sup> a 6,96 x 10<sup>-4</sup> (SI). Geoquimicamente, metaluminoso a peraluminoso, possui altas razes FeOt/(FeOt + MgO) e mostra afinidades com granitos ferrosos, tipo-A do subtipo A2. Os padres dos ETR revelam um ligeiro enriquecimento de ETR leves em relao ao ETR pesados e anomalia negativa acentuada de Eu (Eu/Eu* = 0,08 - 0,13), resultando feio em "gaivota", caracterstica de granitos evoludos. O conjunto de dados obtidos demonstra o carter evoludo do Granito Rio Branco e sua derivao a partir de lquidos reduzidos e enriquecidos em volteis, causadores das transformaes hidrotermais tardias. O estudo comparativo deste corpo com aqueles das sutes anorognicas da Provncia Carajs sugere que o Granito Rio Branco possui maior afinidade com os granitos das sutes Velho Guilherme e, em menor grau, Serra dos Carajs. Por outro lado, claramente distinto da Sute Jamon. Embora apresente caractersticas similares s dos granitos especializados em estanho, no h mineralizaes desta natureza associadas ao corpo.
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O depsito aurfero de Piaba tornou-se a primeira mina em operao no fragmento cratnico So Lus, noroeste do Maranho. Seu ambiente geolgico compreende rochas metavulcanossedimentares do Grupo Aurizona e granitoides da Sute Troma, entre outras unidades menores, formadas em ambiente de arcos de ilhas entre 2240 e 2150 Ma, juntamente com outras unidades menores. A mineralizao caracterizada por uma trama stockwork de veios e vnulas de quartzo com seus halos de alterao (clorita + muscovita + carbonato + pirita + calcopirita e ouro) hospedada em um granodiorito granofrico fino (Granfiro Piaba) e em rocha subvulcnica andestica do Grupo Aurizona. O corpo mineralizado espacialmente limitado zona de cisalhamento ENE-WSW rptil-dctil (Falha Piaba). Estudos petrogrficos, microtermomtricos e por espectroscopia microRaman no quartzo definiram incluses aquo-carbnicas bifsicas e trifsicas, produzidas por aprisionamento heterogneo durante separao de fases, e fluidos aquosos tardios. A soluo mineralizadora corresponde a um fluido aquo-carbnico composto por CO<sub>2</sub> (5 - 24 mol%, densidade de 0,96 - 0,99 g/cm<sup>3</sup>), H<sub>2</sub>O (74 - 93 mol%), N<sub>2</sub> (< 1 mol%), CH<sub>4</sub> (<1mol%) e 5,5 % em peso NaCl equivalente. O minrio depositou a 267 - 302C e 1,25 - 2,08 kbar, correspondendo a profundidades de 4 a 7 km, em consonncia com o regime estrutural. A composio e o intervalo de P-T do fluido mineralizador, combinados com o carter redutor (log <sub>O2</sub> -31,3 a -34,3) e a sulfetao da rocha hospedeira, sugerem que o ouro foi transportado como um complexo sulfetado. O minrio foi depositado em consequncia da separao de fase, reduo da atividade de enxofre e da O<sub>2</sub> pela interao fluido-rocha.
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O depsito de ouro So Jorge, de idade paleoproterozica, est situado na Provncia Aurfera do Tapajs, Crton Amaznico. Ele est hospedado em um anfiblio-biotita-monzogranito constitudo por quartzo, feldspato potssico, plagioclsio, anfiblio, biotita, titanita e opacos. Quatro associaes minerais foram reconhecidas no depsito. A associao 1, formada durante o estgio magmtico, caracterizada pela presena de anfiblio e andesina-oligoclsio. A associao 2 mostra substituio total do anfiblio e intensa saussuritizao do plagioclsio primrio; o epidoto uma fase marcante e a biotita parcialmente cloritizada. As associaes 3 e 4 esto relacionadas aos processos hidrotermais que geraram a mineralizao de sulfeto e ouro. A assemblia 3 dominada por clorita e plagioclsio albtico, com quantidade subordinada de mica branca e, por vezes, biotita. A associao 4 dominada por mica branca, pirita e carbonatos sendo o resultado de uma alterao flica com carbonatao associada. O geotermmetro da clorita sugere temperaturas de 30040 C para as associaes 3 e 4. O geobarmetro do Al na hornblenda indica presses em torno de 1 kbar para a cristalizao dos granitos mineralizados. Condies oxidantes, acima do tampo NNO, prevaleceram durante a gnese dos depsitos. As associaes hidrotermais de So Jorge diferem daquelas descritas nos garimpos Joel e Davi e no so dominadas por epidoto, como sugerido em outras reas da Provncia Tapajs. Um modelo prfiro ou intrusion-related so melhor adaptados para o depsito So Jorge. Este ltimo tem similaridades com o depsito Serrinha da Provncia Juruena e Batalha, na Provncia Tapajs, e fortes analogias com o sistema hidrotermal Volta Grande no sul do Brasil.
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The study area is located in the southern portion of Rio Itapicuru Greenstone Belt, Bahia, where were found rocks that belongs to the Canto Sequence, that comprises felsics and intermediary rocks, beyond metasediments. The studied maps and drill holes help to recognized stratigraphy column that was divided in three mains domains, from the base to the top: andesitics to felsics lavas domain, carbonaceous and metasedimentary domains. The data obtained in mapping and petrography analysis allows classify the area in three deformational phases, Dn, Dn+1, Dn+2. The metamorphism recognized according to the mineralogical associations permitted to classify a progressive regional metamorphism (lower to medium greenchist facies) till biotite zone, falling until chlorite zone due to retrometamorphism. The auriferous mineralizations are mainly related to hydrothermal veins included in the different lithologies, mainly in carbonaceous schists
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The paper deals with the petrographic and geochemical investigation of basalt flows present in a gravel quarry in the town of Mones in northwestern So Paulo State, members of the Serra Geral Formation of the Paran Basin. Were collected 11 samples from different horizons within a topographic vertical profile with an average of 18 meters in height. The samples were subjected to macroscopic and microscopic petrographic and chemical major, minor and trace. The results indicated that it is tholeiitic basalts with dense fine grained average. Petrographic analyzes show that basalts studied are basically constituted by plagioclase (between 33 and 49%), labradorite and clinopyroxenes (between 29 and 46%) represented by the subordinate pigeonite and augite, having as accessories opaque (between 3 and 15% ), olivine (<2%), apatite and zircon as dashes. The secondary minerals correspond to cloropheite, chlorite, serpentine, epidote, albite and iron oxides and hydroxy as well as bowlingit of clay, nontronite, and celadonite. The basalts are kind of high-titanium (Hti)> 1.8% TiO2, and apparently belong to the Pitanga magma-type. The geochemical analyzes proved unsatisfactory for the determination of a probable lithogeochemistry differentiation within the vertical stroke for generating multiple data correlation or no immediately discernible trends
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Main occurrence of Cu-Au in Goias Magmatic Arc, the Chapada mine fits into the geological context of the Brasilia Fold Belt, specifically in the Mara Rosa Magmatic Arc. Four targets, named Hidrotermalito Norte and Sul, NW Chapada Mine Portion and Suruca, are situated in this context, which includes ortogneisses and rocks from the Mara Rosa volcanic-sedimentary sequence. All these targets have been studied due to the possibility of presenting a great potential in Cu-Au, as well as the Chapada mine. Hidrotermalitos Norte and Sul targets presents four lithological sequences, which were identified as: quartz-muscovite schist; muscovite quartzites and kyanite quartzites; quartz-biotite-amphibole schist with pyrite and epidote-amphibole-biotite gneisses with muscovite; muscovite-biotite gneisses. They are metamorphosed to amphibolites facies and retrogressive greenschist facies. Sulfetation represented mainly by pyrite. In the NW Chapada Mine Portion, three main lithological groups were identified and classified as biotite gneisses; honblende-quartz-biotite-schist; amphibolites, with the first group metamorphosed in greenschist facies (low grade), and the other two groups metamorphosed in amphibolites facies, with subsequent retrogressive metamorphism in greenschist facies. Sulfetation is represented by chalcopyrite and pyrite. Finally, also three main lithological groups were identified in the Suruca target, classified as garnet-chlorite-epidote-eiotite gneiss; biotite gneiss and chlorite-biotite gneiss with epidote and muscovite; muscovite-quartz schist, all them metamorphised in amphibolites, with retrometamorphism in greenschist facies. Sulfetation represented by pyrite and sphalerite
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The study area of the Guarda-Mor target (Israelndia-GO) contextualizes the terrains of the estaern portion of the Arenpolis Magmatic Arc, more accurately, the Neoproterozoic associations inserted in the field of the Jaupaci volcano-sedimentary sequence. The mapped area is located in the central-western of Gois state. The presente paper has as main objective to characterize the structural, petrographic and litogeochemistry of the target rocks beyond to compare these factors with the Mina Bacilndia rocks (Fazenda Nova-GO) in order to assess the genetic similarity of volcano-sedimentary units and deposits associated. The Guarda-Mor target is represented by the Jaupaci metavolcanic rocks sequence presenting bimodal volcanism. This sequence consists in metafelsic rocks like sericite/muscovite quartz schist, phyllite and metarriolites and/or metariodacites with calc-alkaline geochemical signature and metamafic rocks with tholeiitic character formed by actinolite - chlorite schist and chlorite - quartz schist. Besides the package of supracrustal rocks also can be observed the occurrence of a local intrusion syn- to late - tectonic named Granito Subvulcnico. In the study area beyond the marked volcanism also seen an event of crustal melting granitognese evidenced by the presence of 2 granites at the east and the west of the map, Granito Israelndia and Granito Ipor respectively. Structural analysis both at the macro and micro have identified 3 deformation phases. The types of rock on the region record features in the metamorphic facies top and down. These features were subdivided into 3 metamorphic areas: the east and West areas show thermal metamorphism due to intrusion of adjacente granites while the central domain displays features of regional metamorphism. Gold mineralization of the Guarda Mor deposit target suggests a possible structural control beyond pronounced the hydrothermal alteration. The mineralization may also be...
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In the Serra de Jacobina, localized in the North Central portion of the state of Bahia, occours the Jacobina Group. Its a sedimentary basin and the gold deposit is stocked on the basal portion, which consist on quartzites intercalated with oligomtico metaconglomerates of Serra do Crrego Formation. There are controversies about the origin of the gold mineralization, but the currently most accepted hypothesis corresponds to a paleoplacer deposit with subsequent ore remobilization and concentration by hydrothermal process. The sulphidation is one of the main results of hydrothermal process, which was more detail characterized, besides identifying if there was more than one sulfides phase generation and its relationship with gold mineralization. The analyzes were performed from the main reef's (metaconglomerates mineralized levels) of Mine Canavieiras: Maneira, Holandez, Liberino, Piritoso, MU and LU. Chemical analyzes semi-quantitative were developed with EDS in MEV and also petrographics analyses. The main sulfide is pyrite, followed by chalcopyrite. Six groups of pyrite were classified according with chemical composition, however they show similarities in their habit and occurrence. Were identified four types of chlorite, labeled A, B, C, D. Gold occurs in free form, associate to pyrites, to Fe-Ti-Muscovite, to chlorite type B and to microfractures with iron hydroxide. Gold presents three different compositions: pure, with Ag or associated with U-Zr. The results of chemical analysis showed that the hydrothermal process have as their main source, ultramafic rocks present in the Jacobina Basin
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Studies of mafic-ultramafic bodies have been carried out through the years due to their great use on the interpretation of geochemical and geotectonic processes that took place in Earth's history. Amongst them, chromitites are notably recognized for being excellent indicators of their parental magma chemistry and of different geotectonic environments, as well for frequently containing associated noble metals mineralization. Thus the investigation of one of this ultramafic bodies that occurs inside the Pilar de Gois Greenstone Belt was proposed, resulting in a detailed map of the chromitites and country rocks, as well as innumerous new data on the chemistry of chromite and associated matrix and accessory minerals. These studies were based upon geological field observations, optic and Scanning Electron Microscope (SEM), besides electron microprobe and cathodoluminescence analysis performed at the Eugen F. Stumpfl Laboratory of the Montanuniversitt Institute of Resource Mineralogy, University of Leoben - Leoben, Austria. The chromitites are composed of 40-70% in volume of chromite (~50% on average), 14-55% of talc (~30% on average), 3-60% of chromium rich chlorite (~20% on average), traces to 4% of iron hydroxides and traces to 3% of rutile (1,5% on average). The chromite occurs as large spherical aggregates or as fine grained subhedral crystals disseminated in the matrix. This aggregates have diameters of 0.3-1.5 cm (1 cm on average) and are extremely well rounded, massive to intensively fractured, and commonly deformed to ellipsoids. When observed under the microscope, these aggregates show well rounded to slightly irregular borders, but on their interiors, these structures are represented by fine to medium grained euhedral to subhedral chromite crystals that have sharp contacts between themselves. The rock's matrix is basically made of chlorite and talc that define a metamorphic foliation (Sn), being the talc an alteration product ...
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The study area is includes in the geological context of Arenpolis Magmatic Arc, a region where there are neoproterozoic associations of granodioritic and tonalitic composiotion. (Ortogneisses of the western Gois) and sequences metavolcanic-sedimentary (Jaupaci Metavolcanic-sedimentary Sequence ). In the mapped area, both units are covered by a cover-laterite. The Ortogneisses from Gois West consist of a source granodioritic gneisses, corresponding to the Biotite granodiorite gneisse, and also by tonalitic gneiss composition corresponding to Metatonalit. The Jaupaci Metavolcanic-sedimentary Sequence is formed by Chlorite Schist (Metabasalt), Biotite Schist (Metadacite) and Sericite Schist (Metarhyolite), and even intrusions Sin/Tardi e Post Tectonic, granite to diorite composition (Diorites), and alson tonalitic (Bacilandia Tonalite). Post tectonic intrusions are observed, wich were Hornblend Diorite Porphyry and Lamprophyres, Structural analysis allowed the identification of three deformational events, Dn-1, Dn and Post-Dn. The first event is associated with a bygone foliation, lineation which generates an intersectional event, generating the foliation Sn, this being the most important structure in the study area, generating even the type mineral lineation and stretch. The last deformational event is characterized by folds on different scales, affecting the Sn foliation. The rocks of the region have features s active hydrothermal and regional metamorphism, and are composed os assembly indicative of mineralogical facies metamorphism Green Schist, in chlotite zone, with evidence of retro metamorphism. Locally there are sulfides as pyrite, arsenopyrit and pyrhotite, and te mineralization is associated with the arsenopyrite
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This study evaluated the effect of the addition of 5% calcium chlorite (CaCl2) on pH values in calcium hydroxide pastes (CH), with or without 2% chlorhexidine digluconate (CHX) used as vehicle, in several periods analysis. Polyethylene tubes were filled with CH mixed with water (G1), 2% CHX solution (G2) or gel (G3), or CHX solution or gel with 5% CaCl2 (G4 and G5, respectively). All tubes were individually immersed in distilled water. After 12, 24 hours, 7, 14 and 28 days, pH value was evaluated directly in water which the tubes were stored. Data were submitted to ANOVA and Tukey tests (=0.05). In 24 hs and 14 days, pH values were similar to all groups. In 12 hs, the G1 presented lower pH value than other groups except to G4 (p < 0.05), and G4 presented lower pH value than G5 (p < 0.05). In 7 days, G1 presented lower pH value than G4 and G5 (p < 0.05). In 28 days, G1 and G5 presented lower pH values than G2 and G4 (p < 0.05) and among other groups there are no statistical differences (p > 0.05). The pH values increased in long-term analysis to all CH pastes. The association of 5% calcium chloride with 2% CHX solution as vehicle of CH paste provided a pH value increase in relation to CH mixed with distilled water. The CHX gel interfered negatively on pH value in comparison to CHX solution when mixed with CaCl2.
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The aim of this study was to evaluate the presence of residues of sodium hypo-chlorite gel, chlorhexidine gel, and EDTA gel on dentina l walls after canal preparat ion throughchemical SEM- elemental chemical microanal ys is (EDS) analysis. Forty-eight single-rootedteeth were selected. They had their crowns sectioned and were instrumented with a reciprocat-ing system. The canals were irrigated with 5 mL of saline solution during root canal preparation.After instrumentation, the root canals were irrigated with 3 mL 17% EDTA followed by 1 min ofultrasonic passive activation (33 20 sec) to remove the smear layer, and then irrigated with3 mL of saline solution. The specimens were randomized into three groups (n 5 12) accord ing tothe chemical substance that lled the root canal for 30 min: GI: 5.5% sodium hypochlorite gel;GII: 2% chlorhexidine gel; GIII: 24% EDTA gel; Negative c ontrol group: no substance was used.Then, the root canals were irrigated with 6 mL of saline solution followed by 1 min of ultrasonicpassive activation (33 20 sec). After ultrasonic activation , the canals were irrigated with 2 mLsaline. The roots were sect ioned, and the perce ntage of each chemical element present in thesamples was analyzed through chemi cal SEM-EDS microanalysis. All expe rimental groupsshowed a signicantly higher percentage of chemical elements (Na and/or Cl) than the controlgroup (P < 0.03). This in vitro study has shown that, regardless of chemical solutions used evenafter the nal irrigation protocol, chemical residues of d ifferent substances remained attached tothe r oot c anal wa lls. Microsc. Res. Tech. 78:49549 9, 2015.
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Ps-graduao em Qumica - IQ
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Subduction zones are one of the most characteristic features of planet Earth. Convergent plate junctions exert enormous influence on the formation and recycling of continental crust, and they are also responsible for major mineral resources and earthquakes, which are of crucial importance for society. A subduction-related geologic unit containing high-pressure rocks occurs in the Barragan area (Valle del Cauca Department) on the western flank of the Central Cordillera of the Colombian Andes. Blueschists and amphibolites, serpentinized meta-ultramafic rocks, graphite-chlorite-muscovite-quartz schists, protocataclasites, and graphite-chlorite-andalusite-andesine-garnet-muscovite +/- titanite schists are exposed in this region. In spite of the petrotectonic importance of blueschists, the high-pressure metamorphism of the Central Cordillera of Colombia has been rarely studied. New geochemical data indicate that protoliths of the blueschist- and amphibolite-facies rocks possessed normal mid-ocean ridge basalt bulk compositions. Ar-40/Ar-39 geochronology for a metapelite rock associated with the blueschists shows a plateau age of similar to 120 million years. We suggest that high-P/T conditions were present from similar to 150 to 125 Ma, depending on the model of generation and exhumation considered.
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This paper presents the classification of 110 copper ore samples from Sossego Mine, based on X-ray diffraction and cluster analysis. The comparison based on the position and the intensity of the diffracted peaks allowed the distinction of seven ore types, whose differences refer to the proportion of major minerals: quartz, feldspar, actinolite, iron oxides, mica and chlorite. There was a strong correlation between the grouping and the location of the samples in Sequeirinho and Sossego orebodies. This relationship is due to different types and intensities of hydrothermal alteration prevailing in each body, which reflect the mineralogical composition and thus the X-ray diffractograms of samples.
