How Are the Emplacement of Rare-Element Pegmatites, Regional Metamorphism and Magmatism Interrelated in the Moldanubian Domain of the Variscan Bohemian Massif, Czech Republic?

Melleton, Jérémie; Gloaguen, Éric; Frei, Dirk; Novák, Milan; Breiter, Karel

doi:10.3749/canmin.50.6.1751

Cited by 77 publications

(33 citation statements)

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“…These deposits formed during Carboniferous to Permian times between 330 Ma and 280 Ma in relation to the lateVariscan orogenic evolution [6][7][8][9][10]. In France, the Beauvoir granite represents one of the best examples of a PHP-RMG with a disseminated Sn-Li-Ta-Nb-Be mineralization [5] and was intensively studied during the 1980s-1990s, with the 900 m of continuous core drilling GPF1 from the "Géologie Profonde de la France" program [11].…”

Section: Introductionmentioning

confidence: 99%

Geochemical Signature of Magmatic-Hydrothermal Fluids Exsolved from the Beauvoir Rare-Metal Granite (Massif Central, France): Insights from LA-ICPMS Analysis of Primary Fluid Inclusions

et al. 2017

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The Beauvoir granite (Massif Central, France) represents an exceptional case in the European Variscan belt of a peraluminous raremetal granite crosscutting an early W stockwork. The latter was strongly overprinted by rare-metal magmatic-hydrothermal fluids derived from the Beauvoir granite, resulting in a massive topazification of the quartz-ferberite vein system. This work presents a complete study of primary fluid inclusions hosted in quartz and topaz from the Beauvoir granite and the metasomatized stockwork, in order to characterize the geochemical composition of the magmatic fluids exsolved during the crystallization of this evolved rare-metal peraluminous granite. Microthermometric and Raman spectrometry data show that the earliest fluid (L1) is of high temperature (500 to >600 ∘ C), high salinity (17-28 wt.% NaCl eq), and Li-rich ( e < −70 ∘ C) with Na/Li ratios ∼5. LA-ICPMS analyses of L1-type fluid inclusions reveal that the chemical composition of this magmatic-hydrothermal fluid is dominated by Na, K, Cs, and Rb, with significant concentrations (10 1 -10 4 ppm) in rare-metals (W, Nb, Ta, Sn, and Li). This study demonstrates that primary fluid inclusions preserved the pristine signature of the magmatic-hydrothermal fluids in the Beauvoir granite but also in the metasomatized W stockwork, despite the distance from the granitic cupola (>100 m) and interaction with external fluids.

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Section: Introductionmentioning

confidence: 99%

Geochemical Signature of Magmatic-Hydrothermal Fluids Exsolved from the Beauvoir Rare-Metal Granite (Massif Central, France): Insights from LA-ICPMS Analysis of Primary Fluid Inclusions

et al. 2017

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“…However, an increasing number of studies describe felsic pegmatites that are considered to be derived by direct partial melting rather than by fractional crystallisation of a parent granite. Examples include the Münchberg Massif, Germany (Franz and Smelik, 1995); Brattstrand Bluffs, East Antarctica (Fitzsimons, 1996); Larsemann Hills, East Antarctica (Carson et al, 1997); Urdach and Espéchère, in the western Pyrénées (Pin et al, 2006); the Fraser Lake area of Northern Saskatchewan, Canada (McKechnie et al, 2012); and the Moldanubian domain of the Bohemian Massif, Czech Republic (Melleton et al, 2012). In many cases granitic pegmatites are described as being derived by extended fractional crystallisation of a fertile parent granite, even where a parent granite body remains enigmatic (Crouse and Č erný , 1972;Jahns and Ewing, 1976;Stilling et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Petrogenesis of rare-metal pegmatites in high-grade metamorphic terranes: a case study from the Lewisian Gneiss Complex of north-west Scotland

Shaw

Goodenough

Horstwood³

et al. 2016

Applied Earth Science

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a b s t r a c tMany rare metals used today are derived from granitic pegmatites, but debate continues about the origin of these rocks. It is clear that some pegmatites represent the most highly fractionated products of a parental granite body, whilst others have formed by anatexis of local crust. However, the importance of these two processes in the formation of rare-metal pegmatites is not always evident.The Lewisian Gneiss Complex of NW Scotland comprises Archaean meta-igneous gneisses which were highly reworked during accretional and collisional events in the Palaeoproterozoic (Laxfordian orogeny). Crustal thickening and subsequent decompression led to melting and the formation of abundant granitic and pegmatitic sheets in many parts of the Lewisian Gneiss Complex. This paper presents new petrological, geochemical and age data for those pegmatites and shows that, whilst the majority are barren biotite-magnetite granitic pegmatites, a few muscovite-garnet (rare-metal) pegmatites are present. These are mainly intruded into a belt of Palaeoproterozoic metasedimentary and meta-igneous rocks known as the Harris Granulite Belt.The rare-metal pegmatites are distinct in their mineralogy, containing garnet and muscovite, with local tourmaline and a range of accessory minerals including columbite and tantalite. In contrast, the biotitemagnetite pegmatites have biotite and magnetite as their main mafic components. The rare-metal pegmatites are also distinguished by their bulk-rock and mineral chemistry, including a more peraluminous character and enrichments in Rb, Li, Cs, Be, Nb and Ta. New U-Pb ages (c. 1690-1710 Ma) suggest that these rare-metal pegmatites are within the age range of nearby biotite-magnetite pegmatites, indicating that similar genetic processes could have been responsible for their formation.The peraluminous nature of the rare-metal pegmatites strongly points towards a metasedimentary source. Notably, within the Lewisian Gneiss Complex, such pegmatites are only found in areas where a metasedimentary source is available. The evidence thus points towards all the Laxfordian pegmatites being formed by a process of crustal anatexis, with the formation of rare-metal pegmatites being largely controlled by source composition rather than solely by genetic process. This is in keeping with previous studies that have also challenged the widely accepted model that all rare-metal pegmatites are formed by fractionation from a parental granite, and raises questions about the origin of other mineralised pegmatites worldwide.

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“…In-situ U-Pb geochronology by LA-ICPMS on columbite-group minerals has been developed in the 2000s (Smith et al 2004) and is now widely applied for pegmatite age determination (Melcher et al 2008;Dewaele et al 2011;Melleton et al 2012;Deng et al 2013;Melcher et al 2015). However, most geochronological studies have used zircon standardization, arguing that matrix-dependent effects are low (Melcher et al 2008).…”

Section: Columbite Versus Zircon Datingmentioning

confidence: 99%

U-Pb geochronology on zircon and columbite-group minerals of the Cap de Creus pegmatites, NE Spain

et al. 2016

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Aquesta és una còpia de la versió author's accepted manuscrit d'un article publicat a la revista Mineralogy and petrology Abstract The Cap de Creus granitic pegmatites in the eastern Catalan Pyrenees were dated using in situ U-Pb geochronology by laser ablation ICP-MS on zircon and columbite-group minerals (CGM), which are present in the different types of pegmatites from type I (K-feldspar pegmatites, least evolved) to type IV (albite pegmatites, most evolved) and therefore allow dating the different ManuscriptClick here to download Manuscript publication_text_v9. doc 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2 pegmatitic pulses. In a type III pegmatite where zircon and CGM are co-genetically associated in the same sample, both minerals were dated using zircon and tantalite reference materials, respectively, to avoid laser-induced matrix-dependent fractionation. In one sample, xenotime genetically associated with zircon was also dated. Two ages were obtained for type I and three ages for type III pegmatites. Three of these 5 ages range from 296.2 ± 2.5 to 301.9 ± 3.8 Ma and are allocated to the primary magmatic stage of crystallization and therefore to the emplacement event.Two younger ages (290.5 ± 2.5 and 292.9 ± 2.9 Ma) obtained on secondary zircon and xenotime, respectively, are interpreted as late post-solidus hydrothermal remobilization. There is no age difference between type I and type III pegmatites. The mean 299 Ma primary magmatic age allows the main late Carboniferous deformation event to be dated and is also synchronous with other peraluminous and calc-alkaline granites in the Pyrenees. However, the youngest ages around 292Ma imply that tectonics was still active in Early Permian times in the Cap de Creus area. IntroductionThe Cap de Creus peninsula (NE Spain) in the easternmost end of the Pyrenean Axial Zone is a remarkable center of interest for geologists because of its well-exposed outcrops that reveal a complex tectonic, metamorphic and magmatic history. Several episodes of deformation and regional metamorphism are accompanied by calc-alkaline and peraluminous magmatism and affected a late Proterozoic series of metasediments and metavolcanics during the Variscan orogeny. An important group of mineralized granitic pegmatites is associated with these tectonic events.The study of granitic pegmatites in Europe is gaining interest because these highly fractionated rocks are important sources of industrial minerals and strategic metals such as Li and the high field strength elements Nb-Ta and Sn (Linnen et al. 2012). In Europe rare-element granitic 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 ...

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How Are the Emplacement of Rare-Element Pegmatites, Regional Metamorphism and Magmatism Interrelated in the Moldanubian Domain of the Variscan Bohemian Massif, Czech Republic?

Cited by 77 publications

References 56 publications

Geochemical Signature of Magmatic-Hydrothermal Fluids Exsolved from the Beauvoir Rare-Metal Granite (Massif Central, France): Insights from LA-ICPMS Analysis of Primary Fluid Inclusions

Geochemical Signature of Magmatic-Hydrothermal Fluids Exsolved from the Beauvoir Rare-Metal Granite (Massif Central, France): Insights from LA-ICPMS Analysis of Primary Fluid Inclusions

Petrogenesis of rare-metal pegmatites in high-grade metamorphic terranes: a case study from the Lewisian Gneiss Complex of north-west Scotland

U-Pb geochronology on zircon and columbite-group minerals of the Cap de Creus pegmatites, NE Spain

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