Palaeozoic granitoids from the French Massif Central: age and origin studied by 87Rb87Sr system

Duthou, Jean-Louis; Cantagrel, J. M.; Didier, Jean; Vialette, Y.

doi:10.1016/0031-9201(84)90039-6

Cited by 97 publications

(53 citation statements)

References 12 publications

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“…Post-thickening crustal melting responsible for Variscan magmatism and hightemperature regional metamorphism in the Cévennes area is geologically well documented (Duthou et al, 1984, Ledru et al, 1989, Pin and Duthou, 1990, Montel et al, 1992, Faure et al, 2001and Faure et al, 2002.…”

Section: Discussionmentioning

confidence: 99%

“…This protolith age agrees with previous results, since the augen orthogneiss west of the Velay Dome is dated at 528 ± 9 Ma by whole-rock Rb-Sr dating (R'kha Chaham et al, 1990). More generally, Early Cambrian orthogneisses are well known from the Massif Central (Duthou et al, 1984).…”

Section: Discussionmentioning

confidence: 99%

“…In the southern Massif Central, top-tothe-south ductile shearing caused nappe stacking (e.g., Ledru et al, 1989 andFaure et al, 1997;and references therein). After the continental collision, the Variscan belt underwent major crustal melting from Late Devonian to Late Carboniferous times, at the expense of metapelites and metagranites (e.g., Duthou et al, 1984 andDuthou, 1990). The Cévennes area is a circa 5-km-thick stack of thrust sheets with metapelite, metagraywacke and quartzite belonging to the Parautochtonous Unit that was transported southward over an underlying augen orthogneiss and biotite-muscovite paragneiss units (Faure et al, 2001).…”

Section: Geological Settingmentioning

confidence: 99%

“…By analogy with the southern Cévennes area, it is likely that the ductile synmetamorphic deformation, which produced the orthogneiss, occurred around 340-335 Ma. The age of the granitic protolith is presently unknown, but in other places of the French Massif Central such orthogneisses yield Cambrian or Ordovician ages (e.g., Duthou et al, 1984 andDuthou, 1990). Under the microscope, the leucosome consists of quartz and K-feldspar recrystallized under high-temperature conditions (Fig.…”

Section: Migmatitementioning

confidence: 99%

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Electron microprobe monazite geochronology of magmatic events: Examples from Variscan migmatites and granitoids, Massif Central, France

Mézème

Cocherie

Faure³

et al. 2006

Lithos

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To cite this version:Eugène Abstract U-Th-Pb dating of monazite with the electron probe microanalyser (EPMA) is increasingly documented as a reliable geochronological method offering high spatial resolution. This method has been applied on monazite from the Cévennes migmatites and granitoids from the southeast of the French Massif Central. Measurements were performed on separated grains after systematic back-scattered electron (BSE) imaging. Monazites from migmatites record two main ages: (i) a protolith age of about 550-543 Ma obtained on inherited cores, and (ii) a migmatization event between 329 ± 5 and 323 ± 3 Ma recorded by monazite rims and all other monogenetic grains. Monazite from the peraluminous Rocles pluton yields a 318 ± 3 Ma age. Finally, three granite dykes are dated at 333 ± 6, 318 ± 5 and 311 ± 5 Ma; the older dyke is the most deformed of them and is interpreted as linked to the migmatization event; the two other dykes are geochronologically, petrologically and structurally coeval with the Rocles pluton. The data constrain the timing of crustal melting following Variscan thickening in the northern Cévennes area. Migmatization of Ordovician protoliths took place at 329-323 Ma and was shortly followed by intrusion of leucogranite at 318-311 Ma. The study shows that EPMA dating of monazite can be successfully used to resolve a close succession of regional melting events.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Migmatitementioning

confidence: 99%

See 2 more Smart Citations

Electron microprobe monazite geochronology of magmatic events: Examples from Variscan migmatites and granitoids, Massif Central, France

Mézème

Cocherie

Faure³

et al. 2006

Lithos

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“…The Sioule metamorphic series is located at the northern boundary of the Guéret, St-Gervais, Manzat, and Champ-Valmont granites, which represent large peraluminous cordierite-biotite intrusions emplaced during the Late Devonian to Early Carboniferous at ca. 360-350 Ma [31,32]. To the south of the Echassières granitic complex, another type of intrusion of biotite porphyritic subalkaline granite (Pouzol-Servant) is emplaced at ca.…”

Section: Regional Geology Of the North French Massif Central Thementioning

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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Structure

Ledru¹,

Costa²,

Echtler³

1994

Pre-Mesozoic Geology in France and Related Areas

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Palaeozoic granitoids from the French Massif Central: age and origin studied by 87Rb87Sr system

Cited by 97 publications

References 12 publications

Electron microprobe monazite geochronology of magmatic events: Examples from Variscan migmatites and granitoids, Massif Central, France

Electron microprobe monazite geochronology of magmatic events: Examples from Variscan migmatites and granitoids, Massif Central, France

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

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