Consulta: subjectFacets:"Hydrothermal"
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Data/hora: 13/06/2024 04:30:54

Spéciation du cuivre en milieu hydrothermal profond et dans les zones de suintements froids
Provedor de dados: 5
Autores: Aumond, Virginie.
This work presents the copper speciation in the deep ocean and the exchanges existing between different size fractions : particulate, dissolved and colloidal. It focus on the mixing zone between deep sources and seawater. The enhancement of our knowledge and the optimization of instrumentation make possible the development of sampling and analysis strategies accorded with the nature and the accessibility of these extreme environments. A part of this work consisted in the development of effective analysis methods for the quantification of copper and copper’s ligands. Our results showed that physical speciation seems to be essentially controlled by the variations of pH and oxydoreductive caracteristics during the dilution of the hydrothermal fluid by...
Tipo: Text
Palavras-chave: Analyse chimique; Spéciation; Hydrothermal; Cuivre; Sulfures; Dorsale Médio-Atlantique; Lucky Strike; Guaymas; Cuivre -- Spéciation; Bouches hydrothermales.
Ano: 2013
URL: https://archimer.ifremer.fr/doc/00692/80379/83500.pdf

Mineralogy, fluid inclusions and stable isotope study of epithermal Au-Ag-Bi-Te mineralization from the SE Afar Rift (Djibouti)
Provedor de dados: 5
Autores: Moussa, N.; Boiron, M.c-; Grassineau, N.v.; Asael, Dan; Fouquet, Yves; Le Gall, Bernard; Rolet, Joël; Etoubleau, Joel; Delacourt, Christophe.
In this paper, the mineralogy, fluid inclusions and stable isotopes of hydrothermal veins from the SE part of the Afar Rift (Djibouti) were studied. Mineralization occurs as gold-silver in quartz/carbonate veins and is mainly associated with felsic volcanism. The morphologies and textures of quartz show crustiform colloform banding, massive and breccias. Microthermometric measurements were made on quartz-hosted two phases (liquid + vapor) inclusions. Mean homogenization temperature ranges from 150°C to 340°C and ice-melting temperatures range from -0.2°C to - 1.6°C indicating that inclusion solutions contain 0.35 to 2.7 eq. wt. % NaCl. Furthermore, δ18O and δ13C values from calcite range from 3.7 to 26.6 ‰ and -7.5 to 0.3 ‰, respectively. The presence of...
Tipo: Text
Palavras-chave: Fluid inclusions; Stable isotopes; Hydrothermal; Epithermal system; SE Afar Rift; Djibouti.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00494/60528/63991.pdf

Is It First the Egg or the Shrimp? – Diversity and Variation in Microbial Communities Colonizing Broods of the Vent Shrimp Rimicaris exoculata During Embryonic Development
Provedor de dados: 5
Autores: Methou, Pierre; Hernández-ávila, Ivan; Aube, Johanne; Cueff-gauchard, Valerie; Gayet, Nicolas; Amand, Louis; Shillito, Bruce; Pradillon, Florence; Cambon-bonavita, Marie-anne.
Rimicaris exoculata is one of the most well-known and emblematic species of endemic vent fauna. Like many other species from these ecosystems, Rimicaris shrimps host important communities of chemosynthetic bacteria living in symbiosis with their host inside the cephalothorax and gut. For many of these symbiotic partners, the mode of transmission remains to be elucidated and the starting point of the symbiotic relationship is not yet defined, but could begin with the egg. In this study, we explored the proliferation of microbial communities on R. exoculata broods through embryonic development using a combination of NGS sequencing and microscopy approaches. Variations in abundance and diversity of egg microbial communities were analyzed in broods at...
Tipo: Text
Palavras-chave: Hydrothermal; Shrimp; Microbial colonization; Alvinocarididae; Egg development.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00489/60067/63352.pdf

Tectonic structure, lithology, and hydrothermal signature of the Rainbow massif (Mid-Atlantic Ridge 36°14′N)
Provedor de dados: 5
Autores: Andreani, Muriel; Escartin, Javier; Delacour, Adelie; Ildefonse, Benoit; Godard, Marguerite; Dyment, Jerome; Fallick, Anthony E.; Fouquet, Yves.
Rainbow is a dome-shaped massif at the 36°14′N nontransform offset along the Mid-Atlantic Ridge. It hosts three ultramafic-hosted hydrothermal sites: Rainbow is active and high temperature; Clamstone and Ghost City are fossil and low temperature. The MoMARDREAM cruises (2007, 2008) presented here provided extensive rock sampling throughout the massif that constrains the geological setting of hydrothermal activity. The lithology is heterogeneous with abundant serpentinites surrounding gabbros, troctolites, chromitites, plagiogranites, and basalts. We propose that a W dipping detachment fault, now inactive, uplifted the massif and exhumed these deep-seated rocks. Present-day deformation is accommodated by SSW-NNE faults and fissures, consistent with oblique...
Tipo: Text
Palavras-chave: Rainbow; Hydrothermal; Serpentinization; Atlantic ridge.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00210/32151/30609.pdf

Bioaccumulation des métaux chez le mytilidae hydrothermal Bathymodiolus sp. de la ride médio-atlantique
Provedor de dados: 5
Autores: Rousse, N; Boulegue, J; Cosson, Rp; Fiala-medioni, A.
The hydrothermal environment is characterised, among other things, by a high metal concentration, related to the convective sea-water circulation inside the oceanic crust and its interaction with basaltic rocks. The biological communities associated with the hydrothermal system can survive in this toxic environment owing to their ability to regulate their intracellular metal levels by excretion or accumulation of metal ions in non-toxic forms. Various detoxification processes have been previously studied within an hydrothermal organism: immobilisation and precipitation of the metal in lysosomal systems, or binding to specific and soluble ligands such as metallothioneins. The later are heat stable and characterised by a high content of cysteine. The...
Tipo: Text
Palavras-chave: Bio-accumulation; Métallothionéines; Lysosomes; Toxicité; Hydrothermal; Bioaccumulation; Metallothioneins; Lysosomes; Toxicity; Hydrothermal.
Ano: 1998
URL: http://archimer.ifremer.fr/doc/00325/43662/43238.pdf

Microbial diversity in a submarine carbonate edifice from the serpentinizing hydrothermal system of the Prony Bay (New Caledonia) over a 6-year period
Provedor de dados: 5
Autores: Postec, Anne; Quemeneur, Marianne; Bes, Meline; Mei, Nan; Benaissa, Fatma; Payri, Claude; Pelletier, Bernard; Monnin, Christophe; Guentas-dombrowsky, Linda; Ollivier, Bernard; Gerard, Emmanuelle; Pisapia, Celine; Gerard, Martine; Menez, Benedicte; Erauso, Gael.
Active carbonate chimneys from the shallow marine serpentinizing Prony Hydrothermal Field were sampled 3 times over a 6 years period at site ST09. Archaeal and bacterial communities composition was investigated using PCR-based methods (clone libraries, Denaturating Gel Gradient Electrophoresis, quantitative PCR) targeting 16S rRNA genes, methyl coenzyme M reductase A and dissimilatory sulfite reductase subunit B genes. Methanosarcinales (Euryarchaeota) and Thaumarchaea were the main archaeal members. The Methanosarcinales, also observed by epifluorescent microscopy and FISH, consisted of two phylotypes that were previously solely detected in two other serpentinitzing ecosystems (The Cedars and Lost City Hydrothermal Field). Surprisingly, members of the...
Tipo: Text
Palavras-chave: Hydrothermal; Serpentinization; Alkaline; Prony; Microbial communities.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00467/57916/60307.pdf

First insights into macro-and meiofaunal colonisation patterns on paired wood/slate substrata at Atlantic deep-sea hydrothermal vents
Provedor de dados: 5
Autores: Cuvelier, Daphne; Beesau, Julie; Ivanenko, Viatcheslav; Zeppilli, Daniela; Sarradin, Pierre-marie; Sarrazin, Jozee.
In 2006, paired wood and slate panels, each equipped with a temperature probe, were deployed on three different localities on and around the Eiffel Tower edifice (Lucky Strike vent field, Mid-Atlantic Ridge) within close proximity of visible hydrothermal activity. Recovery of these panels took place in 2008. For this two-year deployment period, the composition of colonising organisms (both macro-and meiofauna) was assessed, along with image analyses of the deployment sites in 2006 and 2008. Very few significant differences in colonisation between organic (wood) and inorganic (slate) panels were revealed. Rather, the locality of deployment and the local environmental conditions and hydrothermal activity were found to influence taxonomic composition....
Tipo: Text
Palavras-chave: Colonisation; Organic and inorganic substrata; Mid-Atlantic Ridge; Hydrothermal; Recruitment; Diversity; Temperature.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00180/29090/27505.pdf

Ni-Cu-Co-rich hydrothermal manganese mineralization in the Wallis and Futuna back-arc environment (SW Pacific)
Provedor de dados: 5
Autores: Pelleter, Ewan; Fouquet, Yves; Etoubleau, Joel; Cheron, Sandrine; Labanieh, Shasa; Josso, Pierre; Bollinger, Claire; Langlade, Jessica.
The Wallis and Futuna back-arc system is a complex area composed of at least two active oceanic spreading centers (Futuna and Alofi spreading centers) and young volcanic zones characterized by diffuse magmatism locally affected by the Samoan hotspot. This geological setting is favorable to the establishment of hydrothermal systems either high-temperature (HT) hydrothermal venting or low-temperature (LT) diffuse flow. During the 2010 Futuna cruise aboard R/V L'Atalante, three remarkable inactive LT Fe-Si-Mn deposits have been discovered (i.e. Utu Uli, Anakele and Utu Sega). Some of the Mn-rich precipitates exhibit the highest base metals concentrations so far recorded in ferromanganese rocks including the well-documented hydrogenetic crusts and polymetallic...
Tipo: Text
Palavras-chave: Hydrothermal; Diffuse flow; Manganese oxyhydroxides; Metal-rich; Seafloor; Wallis and Futuna Island; South-West Pacific.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00350/46164/45862.pdf

Geochemistry and mineralogy of a silica chimney from an inactive seafloor hydrothermal field (East Pacific Rise, 18°S)
Provedor de dados: 5
Autores: Dekov, V. M.; Lalonde, Stefan; Kamenov, G. D.; Bayon, Germain; Shanks, W. C., Iii; Fortin, D.; Fouquet, Yves; Moscati, R. J.
An inactive vent field comprised of dead chimneys was discovered on the ultrafast East Pacific Rise (EPR) at 18°S during the research campaign NAUDUR with the R/V Le Nadir in December 1993. One of these chimneys was sampled, studied and found to be largely composed of silica-mineralized bacterial-like filaments. The filaments are inferred to be the result of microbial activity leading to silica (± Fe-oxyhydroxide) precipitation. The chimney grew from the most external layer (precipitated 226 ± 4 yr. B.P.) towards the central chimney conduit. Hydrothermal activity ceased 154 ± 13 yr. B.P. and the chimney conduit was completely sealed. Mixing between an end-member hydrothermal fluid and seawater explains the Sr–Nd isotopic composition of the chimney....
Tipo: Text
Palavras-chave: Chimney; C-O-Si-Sr-Nd-Pb-Th-U isotopes; Hydrothermal; Seafloor; Silica.
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00280/39143/37698.pdf

Processes Driving Iron and Manganese Dispersal From the TAG Hydrothermal Plume (Mid-Atlantic Ridge): Results From a GEOTRACES Process Study
Provedor de dados: 5
Autores: González-santana, David; Planquette, Helene; Cheize, Marie; Whitby, Hannah; Gourain, Arthur; Holmes, Thomas; Guyader, Vivien; Cathalot, Cecile; Pelleter, Ewan; Fouquet, Yves; Sarthou, Geraldine.
Hydrothermal vents are a recognized source of trace elements to the ocean inventory. Nevertheless, the contribution of slow-spreading ridges remains poorly resolved. To address this, high-resolution dissolved (&lt;0.45 μm) iron (dFe) and manganese (dMn) samples were collected during the GEOTRACES HERMINE GApr07 process study at the Mid Atlantic Ridge. Samples were collected at nine stations, from the TAG vent site to 75 km south-southwest following the neutrally buoyant plume. Concentrations of dMn and dFe ranged from 71 ± 6 and 51 ± 2 nmol kg–1 right above the vent site to 0.43 ± 0.01 and 1.56 ± 0.02 nmol kg–1 at the most distal station, respectively. Using a 5-box model coupled with our data, we show that as the plume traveled away from the vent,...
Tipo: Text
Palavras-chave: Iron; Manganese; Hydrothermal; TAG; Mid Atlantic Ridge; GEOTRACES.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00643/75530/76431.pdf

Sulfide determination in hydrothermal seawater samples using a vibrating gold micro-wire electrode in conjunction with stripping chronopotentiometry
Provedor de dados: 5
Autores: Aumond, Virginie; Waeles, Mathieu; Salaun, Pascal; Gibbon-walsh, Kristoff; Van Den Berg, Constant M. G.; Sarradin, Pierre-marie; Riso, Ricardo D.
A rapid electrochemical stripping chronopotentiometric procedure to determined sulfide in unaltered hydrothermal seawater samples is presented. Sulfide is deposited at -0.25 V (vs Ag/AgCl, KCl 3 M) at a vibrating gold microwire and then stripped through the application of a reductive constant current (typically -2 mu A). The hydrodynamic conditions are modulated by vibration allowing a short deposition step, which is shown here to be necessary to minimize H2S volatilization. The limit of detection (LOD) is 30 nM after a deposition step of 7s. This LOD is in the same range as the most sensitive cathodic voltammetric technique using a mercury drop electrode and is well below those reported previously for other electrodes capable of being implemented in situ....
Tipo: Text
Palavras-chave: Sulfide; Stripping chronopotentiometry; Vibrating electrode; Gold; Seawater; Hydrothermal.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00111/22222/20065.pdf

Blow Your Nose, Shrimp! Unexpectedly Dense Bacterial Communities Occur on the Antennae and Antennules of Hydrothermal Vent Shrimp
Provedor de dados: 5
Autores: Zbinden, Magali; Gallet, Alison; Szafranski, Kamil M.; Machon, Julia; Ravaux, Juliette; Leger, Nelly; Duperron, Sebastien.
In crustaceans, as in other animals, perception of environmental cues is of key importance for a wide range of interactions with the environment and congeners. Chemoreception involves mainly the antennae and antennules, which carry sensilla that detect water-borne chemicals. The functional importance of these as exchange surfaces in the shrimp's sensory perception requires them to remain free of any microorganism and deposit that could impair the fixation of odorant molecules on sensory neurons. We report here the occurrence of an unexpected dense bacterial colonization on surface of the antennae and antennules of four hydrothermal vent shrimp species. Microscopic observation, qPCR and 16S rRNA barcoding reveal the abundance, diversity and taxonomic...
Tipo: Text
Palavras-chave: Hydrothermal; Shrimp; Alvinocarididae; Chemosensory perception; Antennules; Bacteria; Grooming.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00484/59527/62507.pdf

Iron Transformation Pathways and Redox Micro-Environments in Seafloor Sulfide-Mineral Deposits: Spatially Resolved Fe XAS and delta Fe-57/54 Observations
Provedor de dados: 5
Autores: Toner, Brandy M.; Rouxel, Olivier; Santelli, Cara M.; Bach, Wolfgang; Edwards, Katrina J.
Hydrothermal sulfide chimneys located along the global system of oceanic spreading centers are habitats for microbial life during active venting. Hydrothermally extinct, or inactive, sulfide deposits also host microbial communities at globally distributed sites. The main goal of this study is to describe Fe transformation pathways, through precipitation and oxidation-reduction (redox) reactions, and examine transformation products for signatures of biological activity using Fe mineralogy and stable isotope approaches. The study includes active and inactive sulfides from the East Pacific Rise 9 degrees 50'N vent field. First, the mineralogy of Fe(III)-bearing precipitates is investigated using microprobe X-ray absorption spectroscopy (RXAS) and X-ray...
Tipo: Text
Palavras-chave: Hydrothermal; East Pacific Rise; X-ray absorption spectroscopy; Stable isotopes; Micro-environment; Mineral alteration; Iron; Biosignature.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00337/44810/44375.pdf

Sulfate minerals control dissolved rare earth element flux and Nd isotope signature of buoyant hydrothermal plume (EMSO-Azores, 37°N Mid-Atlantic Ridge)
Provedor de dados: 5
Autores: Chavagnac, Valerie; Ali, Hassan Saleban; Jeandel, Catherine; Leleu, Thomas; Destrigneville, Christine; Castillo, Alain; Cotte, Laura; Waeles, Mathieu; Cathalot, Cecile; Laes, Agathe; Pelleter, Ewan; Nonnotte, Philippe; Sarradin, Pierre-marie; Cannat, Mathilde.
While hydrothermal vents are now thought to be a major source of dissolved iron to the oceans, they have always been considered to be a sink for the dissolved rare-earth elements (DREEs). However, true dissolved REE observations in hydrothermal plumes are still lacking. Here we report for the first time the DREE concentrations and neodymium isotopic compositions (DεNd) of buoyant hydrothermal fluids at Lucky Strike (Mid-Atlantic Ridge). We find that 27 to 62% of total hydrothermal DREEs are rapidly scavenged by anhydrite precipitation at the onset of buoyant plume formation. After this initial loss, all DREEs behave quasi-conservatively within the buoyant plume. Dissolved phase εNd (DεNd) in the evolving plume are identical to black smoker DεNd of +9.0 and...
Tipo: Text
Palavras-chave: Black smokers; Rare earth elements; Neodymium isotopes; Hydrothermal; Sulfate minerals; EMSO-Azores.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00456/56733/58511.pdf

Antimicrobial Peptides and Ectosymbiotic Relationships: Involvement of a Novel Type IIa Crustin in the Life Cycle of a Deep-Sea Vent Shrimp
Provedor de dados: 5
Autores: Le Bloa, Simon; Boidin-wichlacz, Céline; Cueff-gauchard, Valerie; Rosa, Rafael Diego; Cuvillier-hot, Virginie; Durand, Lucile; Methou, Pierre; Pradillon, Florence; Cambon-bonavita, Marie-anne; Tasiemski, Aurélie.
The symbiotic shrimp Rimicaris exoculata dominates the macrofauna inhabiting the active smokers of the deep-sea mid Atlantic ridge vent fields. We investigated the nature of the host mechanisms controlling the vital and highly specialized ectosymbiotic community confined into its cephalothoracic cavity. R. exoculata belongs to the Pleocyemata, crustacean brooding eggs, usually producing Type I crustins. Unexpectedly, a novel anti-Gram-positive type II crustin was molecularly identified in R. exoculata. Re-crustin is mainly produced by the appendages and the inner surfaces of the cephalothoracic cavity, embedding target epibionts. Symbiosis acquisition and regulating mechanisms are still poorly understood. Yet, symbiotic communities were identified at...
Tipo: Text
Palavras-chave: Extreme; Hydrothermal; Symbiosis; Host-microbe interaction; Invertebrate immunity; Crustacean.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00643/75534/76413.pdf

The plumbing of Old Faithful Geyser revealed by hydrothermal tremor
Provedor de dados: 5
Autores: Vandemeulebrouck, J.; Roux, Philippe; Cros, Estelle.
Old Faithful Geyser in Yellowstone National Park (USA) has attracted numerous scientific investigations for over two centuries to better understand its geological structure, the physics of its eruptions, and the controls of its intermittency. Using data acquired with a seismic array in 1992, we track the sources of hydrothermal tremor produced by boiling and cavitation inside the geyser. The location of seismic sources identifies a previously unknown lateral cavity at 15m below the surface, on the SW side of the vent, and connected to the conduit. This reservoir is activated at the beginning of each geyser eruption cycle and plays a major role in the oscillatory behavior of the water level in the conduit before each eruption.
Tipo: Text
Palavras-chave: Geyser; Hydrothermal; Seismology; Old Faithful; Tremor.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00171/28263/26703.pdf

On the early fate of hydrothermal iron at deep-sea vents: A reassessment after in situ filtration
Provedor de dados: 5
Autores: Waeles, Mathieu; Cotte, Laura; Pernet-coudrier, Benoit; Chavagnac, V.; Cathalot, Cecile; Leleu, T.; Laes-huon, Agathe; Perhirin, Antoine; Riso, R. D.; Sarradin, Pierre-marie.
Deep-sea hydrothermal venting is now recognized as a major source of iron (Fe), an essential trace element that controls marine productivity. However, the reactions occurring during dispersal from buoyant plumes to neutrally buoyant hydrothermal plumes are still poorly constrained. Here we report for the first time on the dissolved-particulate partition of Fe after in situ filtration at the early stage of mixing at different hydrothermal discharges, i.e., Lucky Strike (37 degrees N), TAG (26 degrees N), and Snakepit (23 degrees N) on the Mid-Atlantic Ridge. We found that hydrothermal iron is almost completely preserved (&gt;90%) in the dissolved fraction, arguing for low iron-bearing sulfide precipitation of iron in basalt-hosted systems with low Fe:H2S...
Tipo: Text
Palavras-chave: Hydrothermal; Iron; Sulfide; Venting; Filtration; Precipitation.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00388/49944/50522.pdf

Origin of organic compounds in fluids from ultramafic-hosted hydrothermal vents of the Mid-Atlantic Ridge
Provedor de dados: 5
Autores: Konn, Cécile.
Natural gas, primarily methane (CH4), is produced in substantial amounts in ultramafic-hosted hydrothermal systems. These systems could also generate oil (heavier hydrocarbons) and the first building blocks of life (prebiotic molecules). In the presence of iron bearing minerals, serpentinisation reactions generate H2. Subsequently, CH4 could be synthesised by Fischer-Tropsch Type (FTT) reaction (4H2 + CO2 -&gt; CH4 + 2H2O) which is an abiotic process. This has lead to the idea of abiotic formation of larger organic molecules. Both thermodynamics and laboratory work support this idea, yet field data have been lacking. This study focuses on determining the organic content of fluids from ultramafic-hosted hydrothermal systems from the Mid-Atlantic Ridge (MAR)...
Tipo: Text
Palavras-chave: Origin of life; Geochemistry; Hydrothermal; Ultramafic; Organic compounds; Hydrocarbons; Serpentinisation; Origine de la vie; Géochimie; Systèmes hydrothermaux; Ultrabasique; Composés organiques; Hydrocarbures; Serpentinisation.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/these-6939.pdf

Hydrocarbons and oxidized organic compounds in hydrothermal fluids from Rainbow and Lost City ultramafic-hosted vents
Provedor de dados: 5
Autores: Konn, Cecile; Charlou, Jean-luc; Donval, Jean-pierre; Holm, N. G.; Dehairs, F.; Bouillon, S.
The first building blocks of life could be produced in ultramafic-hosted hydrothermal systems considering the large amounts of hydrogen and methane generated by serpentinisation and Fischer-Tropsch-Type synthesis, respectively, in those systems. The purpose of this study was to detect and characterise organic molecules in hydrothermal fluids from ultramafic-hosted hydrothermal systems in the Mid-Atlantic Ridge (MAR) region. During the EXOMAR cruise 2005, fluids from the Rainbow (36°14'N) and the Lost City (30°N) hydrothermal fields were collected and treated by Stir Bar Sorptive Extraction (SBSE) and Solid Phase Extraction (SPE). The extracts were analysed by Thermal Desorption-Gas Chromatography-Mass Spectrometry (TD-GC-MS) and GC-MS, respectively....
Tipo: Text
Palavras-chave: Serpentinisation; Organic; Ultramafic; Hydrothermal; Origin of life.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00067/17828/15576.pdf

Micro-structural and compositional variations of hydrothermal epidote-group minerals from a peralkaline granite, Corupá Pluton, Graciosa Province, South Brazil, and their petrological implications
Provedor de dados: 42
Autores: Vlach,Silvio R.F.
Epidote-group minerals, together with albite, quartz, fluorite, Al-poor and Fe-rich phyllosilicates, zircon, and minor oxides and sulphides, are typical hydrothermal phases in peralkaline alkali-feldspar granites from the Corupá Pluton, Graciosa Province, South Brazil. The epidote-group minerals occur as single crystals and as aggregates filling in rock interstices and miarolitic cavities. They display complex recurrent zoning patterns with an internal zone of ferriallanite-(Ce), followed by allanite-(Ce), then epidote-ferriepidote, and an external zone with allanite-(Ce), with sharp limits, as shown in BSE and X-ray images. REE patterns show decreasing fractionation degrees of LREE over HREE from ferriallanite to epidote. The most external allanite is...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Allanite; Epidote; Hydrothermal; Compositional variations; Peralkaline granite; Corupá Pluton; Graciosa Province.
Ano: 2012
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652012000200012