Electron microprobe and LA-ICP-MS study of monazite hydrothermal alteration:

2000 ◽  
Vol 64 (19) ◽  
pp. 3283-3297 ◽  
Author(s):  
Franck Poitrasson ◽  
Simon Chenery ◽  
Thomas J Shepherd
Keyword(s):  
Hydrothermal Alteration ◽  
Electron Microprobe ◽  
Icp Ms

scholarly journals DESENVOLVIMENTO DO MÉTODO DE DATAÇÃO QUÍMICA U-Th-Pb DE MONAZITA POR MICROSSONDA ELETRÔNICA NA UFMG

2013 ◽  
Author(s):  
Alexandre de Oliveira Chaves ◽  
Elizabeth Kerpe de Oliveira ◽  
Luiz Rodrigues Armoa Garcia
Keyword(s):  
Electron Microprobe ◽  
Chemical Data ◽  
Common Lead ◽  
Icp Ms ◽  
Dating Method ◽  
Physics Department ◽  
Chemical Dating

O método de datação química U-Th-Pb (não-isotópica) de monazita por microssonda eletrônica vem sendo desenvolvido há pelomenos 20 anos e já tem o reconhecimento da comunidade geológica por apresentar resultados que se equivalem à geocronologia isotópicaU-Pb. Este mineral contém quantidades negligenciáveis de chumbo comum, guardando apenas Pb radiogênico proveniente do Th e U destemineral. O desenvolvimento deste método no Laboratório de Microanálises do Departamento de Física da Universidade Federal de MinasGerais mostra que os dados químicos de U, Th e Pb de cristais de monazita fornecidos por sua microssonda eletrônica produzem idadesnão-isotópicas para eles que se equiparam às idades isotópicas U-Pb produzidas pela técnica LA-ICP-MS. Grãos de monazita de placersmarinhos de Buena (RJ) isotopicamente datados pelo método U-Pb com idades entre 530 e 580 Ma foram quimicamente datadas na UFMGentre 505 e 580 Ma. Estes resultados são consideravelmente compatíveis e colocam o referido laboratório a disposição da comunidadegeocientífica para obtenção de idades de cristais de monazita.Palavras-Chave: MONAZITA, DATAÇÃO QUÍMICA, MICROSSONDA ELETRÔNICA, UFMG ABSTRACTDEVELOPMENT OF THE MONAZITE U-Th-Pb CHEMICAL DATING METHOD BY USING ELECTRON MICROPROBE AT UFMG. Themonazite U-Th-Pb chemical dating method (non-isotopic) by electron microprobe has been developed for about 20 years and has theacceptance of the geological community by presenting results that are equivalent to the isotope U-Pb geochronology. This mineral containsnegligible amounts of common lead, keeping only radiogenic Pb from the Th and U of this mineral. The development of this method in themicroanalysis laboratory of the Physics Department- UFMG shows that the monazite U, Th and Pb chemical data provided by itsmicroprobe produce non-isotopic ages for it that are similar to the U-Pb isotopic ages produced by LA-ICP-MS technique. Monazite grainsfrom marine placers of Buena (RJ) isotopically dated by method U-Pb between 530 and 580 Ma were chemically dated at UFMG between505 and 580 Ma. These results are consistent each other and put the laboratory available to the geoscience community as a tool inobtaining monazite ages.Keywords: MONAZITE, CHEMICAL DATING, ELECTRON MICROPROBE, UFMG

Arsenopyrite and As-bearing pyrite from the Roudný deposit, Bohemian Massif

2004 ◽  
Vol 68 (1) ◽  
pp. 31-46 ◽  
Author(s):  
J. Zachariáš ◽  
J. Frýda ◽  
B. Paterová ◽  
M. Mihaljevič
Keyword(s):  
Laser Ablation ◽  
Fluid Inclusion ◽  
Electron Microprobe ◽  
Gold Deposits ◽  
Fluid Inclusion Data ◽  
The Core ◽  
Trace Element Chemistry ◽  
Mineral Phases ◽  
Icp Ms ◽  
Substitution Mechanism

AbstractThe major- and trace-element chemistry of pyrite and arsenopyrite from the mesothermal Roudný gold deposits was studied by electron microprobe and laser ablation ICP-MS techniques. In total, four generations of pyrite and two of arsenopyrite were distinguished. The pyrite is enriched in As through an Fe (AsxS1–x)2 substitution mechanism. The As-rich zones of pyrite-2 (up to 4.5 wt.% As) are also enriched in gold (up to 20 ppm), lead (commonly up to 220 ppm, exceptionally up to 1500 ppm) and antimony (commonly <600 ppm, rarely up to 1350 ppm). Positive correlation of As and Au in the studied pyrites is not coupled with an Fe deficiency, in contrast to Au-rich As-bearing pyrites in Carlintype gold deposits. The As-rich pyrite-2 coprecipitated with the Sb-rich (1 –4.2 wt.%) and Au-rich (40 –150 ppm) arsenopyrite-1. The younger arsenopyrite-2 is significantly less enriched in these elements (0 –70 ppm of Au).The chemical zonality of pyrites in the Roudný gold deposits reflects the chemical evolution of orebearing fluids that are not observed in any other mineral phases. The data available suggest relatively high activity of sulphur and low activities of arsenic and gold during crystallization of the older pyrite generation (pyrite-1). Later, after particular dissolution of pyrite-1, Au-rich As-bearing pyrite-2 and arsenopyrite precipitated. These facts suggest a marked increase in the arsenic and gold activities in ore-bearing fluids. The As-content of pyrite-2 decreases in an oscillatory manner from the core to the rim, reflecting changes in the As activity or/and in the P-T conditions. The As-bearing pyrites were formed at temperatures of at least 320–330°C, based on arsenopyrite thermometers and fluid inclusion data.

Cathodoluminescence and electron microprobe study of dolomitic marbles from Namibia: Evidence for hydrothermal alteration

1999 ◽  
Vol 150 (2) ◽  
pp. 333-357
Author(s):  
Christian J. Gross ◽  
Klaus Weber ◽  
Axel Vollbrecht ◽  
Siegfried Siegesmund
Keyword(s):  
Hydrothermal Alteration ◽  
Electron Microprobe

Hydrothermal clay mineral formation in a biotite-granite in northern Switzerland

Clay Minerals ◽  
1984 ◽  
Vol 19 (4) ◽  
pp. 579-590 ◽  
Author(s):  
Tj. Peters ◽  
B. Hofmann
Keyword(s):  
Fluid Inclusion ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Hydrothermal Alteration ◽  
Electron Microprobe ◽  
Mineral Chemistry ◽  
Biotite Granite ◽  
Mineral Formation ◽  
Fluid Inclusion Data ◽  
Northern Switzerland

AbstractClay minerals of several hydrothermally altered zones in a 1200-m biotite-granite core from a drillhole in northern Switzerland were studied microscopically, by XRD and by electron microprobe. The minerals principally affected by the hydrothermal alteration were plagioclase (An5-An20) and, to a lesser extent, biotite. Illite, regularly interstratified illite-smectite and dioctahedral chlorite-smectite, dioctahedral chlorite, trioctahedral chlorite and kaolinite were detected in the alteration products. Commonly, two or more clay minerals occurred together in pseudomorphs after plagioclase. The mineral chemistry of the clay minerals showed a predominance of the substitution KAl for Si and, to a lesser extent, MgSi for Al. Fluid-inclusion data and the absence of pure smectite and epidote indicated temperatures of ∼200°C for the fluid that caused this alteration.

scholarly journals Sn-Bearing Minerals and Associated Sphalerite from Lead-Zinc Deposits, Kosovo: An Electron Microprobe and LA-ICP-MS Study

Minerals ◽  
2016 ◽  
Vol 6 (2) ◽  
pp. 42 ◽  
Author(s):  
Joanna Kołodziejczyk ◽  
Jaroslav Pršek ◽  
Panagiotis Voudouris ◽  
Vasilios Melfos ◽  
Burim Asllani
Keyword(s):  
Electron Microprobe ◽  
Icp Ms ◽  
Lead Zinc ◽  
Zinc Deposits

Chevkinite-group minerals from Russia and Mongolia: new compositional data from metasomatites and ore deposits

2012 ◽  
Vol 76 (3) ◽  
pp. 535-549 ◽  
Author(s):  
R. Macdonald ◽  
B. Bagiński ◽  
P. Kartashov ◽  
D. Zozulya ◽  
P. Dzierżanowski
Keyword(s):  
Low Temperature ◽  
Hydrothermal Alteration ◽  
Electron Microprobe ◽  
Compositional Data ◽  
Primary Crystallization ◽  
Ore Deposits ◽  
Compositional Variation ◽  
Published Data ◽  
Exchange Vector ◽  
Compositional Variations

AbstractElectron-microprobe analyses of Russian and Mongolian chevkinite-group minerals from little-known host lithologies, including various metasomatic rocks, quartzolites and an apatite deposit, are presented. The mineral species analysed include chevkinite-(Ce), perrierite-(Ce), polyakovite-(Ce) and Sr- and Zr-rich perrierite-(Ce). Compositional variation in the Sr-rich members of the group is broadly represented by the exchange vector (Fe + Mn + Al + REE) ↔ (Ca + Sr + Ti + Zr). Despite the varied parageneses, the chevkinite-(Ce) compositions are similar to previously published data. Many crystals have strong internal compositional variations, partly produced during primary crystallization and partly during low-temperature hydrothermal alteration.

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