Monazite and zircon as major carriers of Th, U, and Y in peraluminous granites: examples from the Bohemian Massif

Breiter, Karel

doi:10.1007/s00710-016-0448-0

Cited by 22 publications

(27 citation statements)

References 63 publications

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“…(), Wark and Miller (1993), Weber et al. (1985) and Breiter (). The range of leucosome and peraluminous granite Th concentrations are from Inger and Harris (), Villaros et al.…”

Section: Methodsmentioning

confidence: 99%

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Th/U ratios in metamorphic zircon

Yakymchuk

Kirkland

Clark

2018

Journal Metamorphic Geology

305

109

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The Th/U ratios of zircon crystals are routinely used to help understand their growth mechanism. Despite the wide application of Th/U ratios in understanding the geological significance of zircon U–Pb ages, the main controls on the Th/U ratio in metamorphic zircon are poorly understood. Here, phase equilibria modelling coupled with solubility expressions for accessory minerals are used to investigate the controls on the Th/U ratios of suprasolidus metamorphic zircon in an average amphibolite facies metapelite composition. We also present a new database of metamorphic Th/U ratios in zircon from Western Australia. Several factors affecting the Th/U ratio are investigated, including the bulk rock concentrations of Th and U, the amount of monazite in the system, and open v. closed system behaviour. Our modelling predicts that the main controls on the Th/U ratio of suprasolidus metamorphic zircon are the concentrations of Th and U in the system, and the breakdown and growth of monazite in equilibrium with zircon. Furthermore, the relative timing of zircon and monazite growth during cooling and melt crystallization has an important role in the Th/U ratio of zircon. Early grown zircon near the peak of metamorphism is expected to have elevated Th/U ratios whereas zircon that grew near the solidus is predicted to have relatively low Th/U ratios, which reflects the coeval growth of monazite during cooling and melt crystallization. Our modelling approach aims to provide an improved understanding of the main controls of Th/U in metamorphic zircon in migmatites and hence better apply this geochemical ratio as a tool to assist in interpretation of the genesis of metamorphic zircon.

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“…(), Wark and Miller (1993), Weber et al. (1985) and Breiter (). The range of leucosome and peraluminous granite Th concentrations are from Inger and Harris (), Villaros et al.…”

Section: Methodsmentioning

confidence: 99%

“…For natural samples, Th concentrations of coexisting (assumed equilibrated) monazite and melt (e.g. granite or leucosome) yield partition coefficients that mostly range from 1,000 to 10,000 (Bea, Pereira, & Stroh, ; Breiter, ; Förster, ; Montel, ; Pichavant et al., ; Wark & Miller, ; Weber, Barbey, Cuney, & Martin, ). Acosta‐Vigil et al.…”

Section: Methodsmentioning

confidence: 99%

Th/U ratios in metamorphic zircon

Yakymchuk

Kirkland

Clark

2018

Journal Metamorphic Geology

305

109

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“…The cheralite substitution is dominant in the analyzed monazite from all the analyzed suites of the KGB. The predominance of the cheralite substitution over the huttonite substitution was also found in highly fractionated high-F, Li-mica granites from other parts of the Krušné Hory/Erzgebirge batholith and the Fichtelgebirge granites in NE Bavaria, Germany [3,9,27]. High contents of the cheralite component (>20-30 mol %) were also found in highly fractionated S-type granites from the West Carpathian belt [2] and in similar S-type granites from the Belvís de Monroy pluton in the Iberian Variscan belt [7].…”

Section: Substitution In Monazitementioning

confidence: 79%

“…In the last ten years, several studies have emphasized the role of monazite, xenotime, and zircon as major hosts for rare earth elements (REE) and Y in granites [1][2][3][4][5][6][7][8][9]. However, several factors controlling the composition of the above mentioned accessory minerals remain unclear.…”

Section: Introductionmentioning

confidence: 99%

REE and Y Mineralogy of the Krudum Granite Body (Saxothuringian Zone)

René

2018

Minerals

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Abstract:The Krudum granite body comprises highly fractionated granitic rocks ranging from medium-F biotite granites to high-F, high-P 2 O 5 Li-mica granites. This unique assemblage is an ideal site to continue recent efforts in petrology to characterize the role of zircon, monazite, and xenotime as hosts to rare earth elements (REEs). The granitic rocks of the Krudum body analyzed in this study were found to contain variable concentrations of monazite and zircon, while xenotime was only found in the high-F, high-P 2 O 5 Li-mica granites and in the alkali-feldspar syenites of the Vysoký Kámen stock. Intermediate trends between cheralite and huttonite substitutions are characteristic for analyzed monazite grains from all magmatic suites. The highest concentration of cheralite was found in monazite from the alkali-feldspar syenites (up to 69.3 mol %). The proportion of YPO 4 in analyzed xenotime grains ranges from 71 to 84 mol %. Xenotime grains are commonly enriched in heavy rare earth elements (HREEs; 9.3-19.5 wt % HREE 2 O 3 ) and thorite-coffinite and cheralite exchange was observed. Some xenotime analyses return low totals, suggesting their hydration during post-magmatic alterations. Analyzed zircon from granite suites of the Krudum granite body contains moderate Hf concentrations (1.0-4.7 wt % HfO 2 ; 0.010-0.047 apfu Hf). The highest concentrations of HfO 2 were found in zircon from the high-F, high-P 2 O 5 Li-mica granites (1.2-4.7 wt % HfO 2 ). Analyzed zircon grains from the high-F, high-P 2 O 5 Li-mica granites and alkali-feldspar syenites are enriched in P (up to 8.29 wt % P 2 O 5 ; 0.24 apfu P), Al (0.02-2.0 wt % Al 2 O 3 ; 0.00-0.08 apfu Al), Ca (up to 3.9 wt % CaO; 0.14 apfu Ca), Y (up to 5.5 wt % Y 2 O 3 ; 0.10 apfu Y), and Sc (up to 1.17 wt % Sc 2 O 3 ; 0.03 apfu Sc). Zircon grains from the high-F, high-P 2 O 5 Li-mica granites were sometimes hydrated and fluorized. The concentrations of F in zircon from partly greisenised high-F, high-P 2 O 5 Li-mica granites reached up to 1.2 wt % (0.26 apfu F).

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“…Based on predominant LREE incorporated in monazite a suffix is given to denote the most abundant auxiliary element (i.e., monazite(-Ce)) (Voncken, 2016). Monazite occurs as an accessory mineral in peraluminous granites, syenitic and granitic pegmatites, quartz veins, carbonatites, migmatites and paragneisses (FöRsteR, 1998a;bReiteR, 2016). Monazite is considered to be a major host of LREE and smaller fractions of Y, heavy rare earth elements (HREE), and actinides (bea, 1996).…”

Section: Introductionmentioning

confidence: 99%

REE-bearing minerals in Drava river sediments, Slovenia, and their potential origin

Šoster¹,

Zavašnik²,

Ravnjak³

et al. 2017

Geologija

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Monazite and xenotime are major ore minerals for rare earth elements (REE), Y, and actinides, a powerful tool for radiometric dating and indicators of the geological genesis of the parent rock. In this contribution, we present results of microanalysis of monazite and xenotime mineral grains found in heavy mineral sand fraction from Drava river. Investigated grains of monazite(-Ce) were found to be exhibiting varying concentrations of Th, indicating mixed hydrothermal (or greenschist-amphibolite grade) and igneous origin. Monazite was found to be isomorphically replaced by cheralite (CaTh(PO 4 ) 2 ) and subordinately by huttonite (ThSiO 4 ), forming monazitecheralite and monazite-huttonite solid solution. Chemical composition and the degree of isomorphic replacement of monazite grains are indicating their source from rocks of Eclogite belt and Granatspitz massif in Tauern Window, Austria. On the other hand xenotime(-Y) shows consistent concentrations of Y while concentrations of associated heavy rare earth elements (HREE) vary, indicating the origin of mixed affinities. IzvlečekMinerala monazit in ksenotim sta pomemben vir redkih zemelj, itrija in aktinidov. Lahko ju uporabimo tudi kot orodje za radiometrično datiranje (geokronologijo), ter kot indikator geneze matične kamnine. V prispevku predstavljamo rezultate mikroanalize zrn monacita in ksenotima zaznanih v frakciji težkih peskov reke Drave. Cerijev monacit ima spremenljive vsebnosti Th, kar kaže na njegov hidrotermalni izvor ali izvor iz metamorfnih (od faciesa zelenega skrilavca do amfibolitnega faciesa) in magmatskih kamnin. Rezultati mikroanalize monacita kažejo izomorfno nadomeščanje s ceralitom (CaTh(PO 4 ) 2 ) in v manjši meri s huttonitom (ThSiO 4 ), pri čemer tvorijo trdno raztopino. Kemijska sestava in stopnja izomorfnega nadomeščanja monacitnih zrn nakazujejo njihov izvor iz kamnin Eklogitnega pasu in masiva Granatspitz v Visokih Turah v Avstriji. V ksenotimu je najbolj zastopan element Y, ki ima v vseh zrnih enakomerne vsebnosti, medtem ko se vsebnosti težkih redkih zemelj (HREE) spreminjajo, kar kaže na izvor iz različnih geoloških okolij.

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Monazite and zircon as major carriers of Th, U, and Y in peraluminous granites: examples from the Bohemian Massif

Cited by 22 publications

References 63 publications

Th/U ratios in metamorphic zircon

Th/U ratios in metamorphic zircon

REE and Y Mineralogy of the Krudum Granite Body (Saxothuringian Zone)

REE-bearing minerals in Drava river sediments, Slovenia, and their potential origin

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