Geochemical evidence for a multistage magmatic genesis of Ta-Sn-Li mineralization in the granite at Beauvoir, French Massif Central

Raimbault, Louis; Cuney, Michel; Azencott, Claude; Duthou, Jean-Louis; Joron, Jean Louis

doi:10.2113/gsecongeo.90.3.548

Cited by 205 publications

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“…Zircon from the G-b and G-c granites exhibits zoning, represented by the presence of polymineralic micro-inclusions of xenotime-(Y), thorite and uraninite in the core, and enrichment in Hf at the rim. Significant mobility of Hf was postulated as resulting from hydrothermal transfer induced by melt degassing (Raimbault et al 1995). This phenomenon, already cited in studies of other granites (Suzhou: Wang et al 1996, Laoshan: Wang et al 2000, 2001, may be described as follows: In summary, observations based on accessory minerals point to a magmatic environment for the G-a granite.…”

Section: Discussionmentioning

confidence: 84%

Accessory Minerals in the Xihuashan Y-Enriched Granitic Complex, Southern China: A Record of Magmatic and Hydrothermal Stages of Evolution

Wang¹,

Fontan²,

Chen³

et al. 2003

The Canadian Mineralogist

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The Xihuashan granitic complex (southern China) is mainly composed of coarse-grained porphyritic biotite granite (G-a), medium-grained porphyritic biotite granite (G-b), and medium-to fine-grained porphyritic biotite granite (G-c). The G-a granite is characterized by monazite-(Ce) and xenotime-(Y), in addition to commonly observed zircon and uranoan thorite. In the G-b and G-c intrusive units, monazite-(Ce) becomes very scarce, whereas Y-bearing minerals, including Y-bearing spessartine, xenotime-(Y), gadolinite-(Y), fergusonite-(Y), and yttrian fluorite (up to 15 wt% Y 2 O 3 ), are concentrated to various extents. Spessartine exhibits chemical zoning, which is displayed, in the core, by elevated contents of Y and heavy REE (HREE) (up to 2.32 wt% Y 2 O 3 and 1.51% HREE 2 O 3 ) and micrometric inclusions of Y-bearing minerals. Similarly, zircon from the G-b and Gc granites contains polymineralic micro-inclusions in the core. Overall, the accessory minerals point to a magmatic environment of crystallization for the G-a granite. In contrast, the crystallization of the G-b and G-c granites involved magmatic and hydrothermal stages. The late-to postmagmatic fluid is enriched in F and CO 2 , and appeared as a result of the final oversaturation of the granitic melt in a fluid phase.Keywords: yttrian fluorite, yttrium-bearing spessartine-almandine, xenotime-(Y), zircon, electron-microprobe data, granite, Xihuashan, China. in the endo-and exocontact zones of the Xihuashan granitic complex (Hsu 1943). Mining of quartz-ferberitetype ores started in 1935. The metallogeny of the deposits and the petrology of associated granites were described by Hsu

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Section: Discussionmentioning

confidence: 84%

Accessory Minerals in the Xihuashan Y-Enriched Granitic Complex, Southern China: A Record of Magmatic and Hydrothermal Stages of Evolution

Wang¹,

Fontan²,

Chen³

et al. 2003

The Canadian Mineralogist

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“…Raimbault et al, 1995;Breiter et al, 2005). However, in these models volatile separation forms B-depleted, and therefore tourmaline depleted rocks, but the SW England G5 granites contain tourmaline.…”

Section: Topaz (G5) Granitesmentioning

confidence: 99%

“…Raimbault et al, 1995;Černŷ et al, 2005). Peraluminous RMG are characterised by extreme enrichment of Li, B, F, P, and…”

Section: Comparison With Petrogenetic Models For Other Peraluminous Gmentioning

confidence: 99%

The petrogenesis of the Early Permian Variscan granites of the Cornubian Batholith: Lower plate post-collisional peraluminous magmatism in the Rhenohercynian Zone of SW England

Simons

Shail

Andersen

2016

Lithos

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The Early Permian Cornubian Batholith was generated during an extensional regime following Variscan convergence within the Rhenohercynian Zone of SW England. Its component granites can be classified, using mineralogical, textural and geochemical criteria, into five main types, all of which are peraluminous (A/CNK >1.1): G1 (two-mica), G2 (muscovite), G3 (biotite), G4 (tourmaline) and G5 (topaz). G1 granites formed through up to 20% muscovite and minor biotite dehydration melting of a metagreywacke source at moderate temperatures and pressures (731-806°C, >5 kbar). Younger G3 granites formed through higher temperature, lower pressure (768-847°C, <4 kbar) biotite-dominated melting of a similar source. Partial melting was strongly influenced by the progressive lower-mid crustal emplacement of mafic igneous rocks during post-Variscan extension and a minor (<5-10%) mantle-derived component in the granites is possible. Two distinct fractionation series, G1-G2 and G3-G4, are defined using whole rock geochemical and mineral chemical data.Variations in the major elements, Ba, Sr and Rb indicate that G1 and G3 granites underwent 15-30% fractionation of an assemblage dominated by plagioclase, alkali feldspar and biotite to form, more evolved G2 and G4 granites respectively. Decreasing whole rock abundances of Zr, Th and REE support fractionation of zircon, monazite, apatite and allanite. Subsolidus alteration in G2 and G4 granites is indicated by non-primary muscovite and tourmaline and modification of major and trace element trends for G3-G4 granites, particularly for P 2 O 5 and Rb. Topaz (G5) granites show low Zr, REE and extreme enrichment in Rb (up to 1530 ppm) and Nb (79 ppm) that cannot be related in a straightforward manner to continued differentiation of the G1-G2 or G3-G4 series. Instead, they are considered to represent partial melting, mediated by granulite facies fluids, of a biotite-rich restite following extraction of

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“…Geochemically it is a highly specialized, strongly peraluminous (S-type), rare metal-bearing granite enriched with P, F, Li, Rb, Nb, Ta, Sn, and W, and depleted of Si, Fe, Ti, Mg, Sr, Y, REE etc. (Cuney et al 1992;Raimbault et al 1995). The Beauvoir granite is the latest intrusion in a peraluminous granitic complex composed of three successively emplaced units: the hidden more or less hypothetical La Bosse granite, the Colettes two-mica granite, and the Beauvoir topaz-lepidolite-albite granite Cuney et al 1992 ite types intruded into lower-Paleozoic micaschists.…”

Section: Geology and Samplesmentioning

confidence: 99%

“…Three granitic units marked B1 to B3 were distinguished by Rossi et al (1987) and Raimbault & Azencot (1987). Later, a detailed geochemical study divided the Beauvoir granite into two major units: B and B' (Raimbault et al 1995). The B-unit forms the upper part of the stock representing geochemically more evolved, more fluid-enriched part of the Beauvoir initial magma.…”

Section: Geology and Samplesmentioning

confidence: 99%

Vertical zonality of fractionated granite plutons reflected in zircon chemistry: the Cínovec A-type versus the Beauvoir S-type suite

Breiter¹,

Škoda²

2012

Geologica Carpathica

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Abstract:We studied vertical changes in the chemical composition of zircon from two contrasting Variscan granite systems. The Beauvoir system (Massif Central, France) composed of three successive intrusions (B1, B2, B3) represents typical peraluminous S-type granite extremely enriched in P, F, Li, Rb, Cs, Be, Sn, Nb, Ta, and poor in Zr, Th, REE and Y. The Cínovec system (Krušné hory Mts/Erzgebirge, Czech Republic/Germany) composed of two successive intrusions (protolithionite granite, zinnwaldite granite) is only slightly peraluminous, P-poor, F, Li, Rb, Cs, U, Th, REE, Y, Sc, Sn, W, Nb, Ta-rich granite, which may be classified as A-type. In both localities, the most fractionated intrusions are located on the top of the system. Samples from borehole GPF-1 (Beauvoir) represent an 800 m long vertical section through the entire granite stock, while CS-1 borehole (Cínovec) reached a depth of 1600 m. Chemical compositions of zircons from both granite systems show distinct vertical zonality, but their shape and elemental speciation is highly contrasting. At Beauvoir, zircon shows a remarkable increase in Hf-content from 2-4 wt. % HfO 2 (~0.03 apfu Hf) in the deepest B3-unit to 15-19 wt. % HfO 2 (up to 0.18 apfu Hf) in the uppermost B1-unit. The highest contents of F, P, and U were detected in the intermediate unit B2 at a depth of 400-600 m. At Cínovec, Hf shows only moderate enrichment from ca. 2 wt. % HfO 2 in the deeper protolithionite granite to 5-10 wt. % HfO 2 in the uppermost part of the zinnwaldite granite. High contents of Th (3-8 wt. % ThO 2 ) are entirely bound in the uppermost section of the granite copula to a depth of 200 m, but below this level the contents only sporadically exceed 1 wt. % ThO 2 . Concentrations of U, Y, HREE, Sc and Bi also reach their highest values in the uppermost parts of the zinnwaldite granite, but their decrease downward is much gentler. Extreme enrichment of outer zones of zircon crystals from some granites with Hf or high contents of Th, U, REE, Y, Nb and of some other elements in zircons from other localities is not considered to be a specific phenomenon characterizing melts of A-or S-type granite, but reflects a high degree of fractionation of systems rich in Na and F.

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Geochemical evidence for a multistage magmatic genesis of Ta-Sn-Li mineralization in the granite at Beauvoir, French Massif Central

Cited by 205 publications

References 0 publications

Accessory Minerals in the Xihuashan Y-Enriched Granitic Complex, Southern China: A Record of Magmatic and Hydrothermal Stages of Evolution

Accessory Minerals in the Xihuashan Y-Enriched Granitic Complex, Southern China: A Record of Magmatic and Hydrothermal Stages of Evolution

The petrogenesis of the Early Permian Variscan granites of the Cornubian Batholith: Lower plate post-collisional peraluminous magmatism in the Rhenohercynian Zone of SW England

Vertical zonality of fractionated granite plutons reflected in zircon chemistry: the Cínovec A-type versus the Beauvoir S-type suite

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