Počet záznamů: 1  

Composition of zircons from the Cornubian Batholith of SW England and comparison with zircons from other European Variscan rare-metal granites

  1. 1.
    0465588 - GLÚ 2017 RIV GB eng J - Článek v odborném periodiku
    Breiter, Karel - Müller, A. - Shail, R. - Simons, B.
    Composition of zircons from the Cornubian Batholith of SW England and comparison with zircons from other European Variscan rare-metal granites.
    Mineralogical Magazine. Roč. 80, č. 7 (2016), s. 1-17. ISSN 0026-461X. E-ISSN 1471-8022
    Grant CEP: GA ČR GA14-13600S
    Institucionální podpora: RVO:67985831
    Klíčová slova: zircon * chemical composition * Cornwall * rare-metal granite
    Kód oboru RIV: DB - Geologie a mineralogie
    Impakt faktor: 1.285, rok: 2016

    Zircon from 14 representative granite samples of the late-Variscan Cornubian Batholith in SW England was analyzed for W, P, As, Nb, Ta, Si, Ti, Zr, Hf, Th, U, Y, La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb, Al, Sc, Bi, Mn, Fe, Ca, Pb, Cu, S, and F using EPMA. Zircons from the biotite and tourmaline granites are poor in minor and trace elements, usually containing 1.0– 1.5 wt% HfO2, <0.5 wt% UO2 and P2O5, <0.25 wt% Ysub.2O3, <0.2 wt% Sc2O3 and Bi2O3, and <0.1 wt% ThO2 Zircon from topaz granites from the St. Austell Pluton, Meldon Aplite and Megiliggar Rocks are slightly enriched in Hf (up to 4 wt% HfO2), U (1– 3.5 wt% UO2), and Sc (0.5–1 wt% Sc2O3). Scarce metamictized zircon grains are somewhat enriched in Al, Ca, Fe, and Mn. The decrease of the zircon Zr/Hf ratio, a reliable magma fractionation index, from 110-60 in the biotite granites to 30-10 in the most evolved topaz granites (Meldon Aplite and Megiliggar Rocks), supports a comagmatic origin of the biotite and topaz granites via long fractionation of common peraluminous crustal magma. In comparison with other European rare-metal provinces, the overall contents of trace elements in Cornubian zircons are low and the Zr/Hf- and U/Th-ratios show lower degrees of fractionation of the parental melt.
    Trvalý link: http://hdl.handle.net/11104/0264084

     
     
Počet záznamů: 1  

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