preprints.org > environmental and earth sciences > geochemistry and petrology > doi: 10.20944/preprints201804.0117.v1

Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Version 1 : Received: 9 April 2018 / Approved: 10 April 2018 / Online: 10 April 2018 (08:20:50 CEST)

The Krudum granite body comprises highly fractionated granitic rocks ranging from medium-F biotite granites to high-F, high-P₂O₅ 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 REEs. The granitic rocks of the Krudum body analysed in this study were found to contain variable concentrations of monazite and zircon, while xenotime was only found in the high-F, high-P₂O₅ Li-mica granites and in the alkali-feldspar syenites of the Vysoký Kámen stock. For analysed monazites of all magmatic suites cheralite substitution was significant. The highest concentration of cheralite was found in monazites from the high-F, Li-mica granites and from the alkali-feldspar syenites. The proportion of YPO₄ in all analysed xenotimes ranges from 71 to 84 mol. %. Some xenotimes were found to be hydrated and the observed water content estimated from analytical data ranged from 5 to 11 wt. % H₂O. Analysed xenotimes were commonly enriched in HREEs (9.3– 19.5 wt. % HREE₂O₃) and thorite-coffinite and cheralite exchange was observed. Analysed zircons from granite suites of the Krudum granite body contained moderate Hf concentrations (1.0–4.7 wt. % HfO₂; 0.010–0.047 apfu Hf). The highest concentrations of HfO₂ were found in zircons from the high-F, high P₂O₅ Li-mica granites (1.2–4.7 wt. % HfO₂) and from the alkali-feldspar syenites (1.3–4.1 wt. % HfO₂). Zircons from the high-F, high-P₂O₅ Li-mica granites were often hydrated and fluorised. The concentrations of F in zircon from partly greisenised high-F, high-P₂O₅ Li-mica granites reached up to 1.2 wt. % (0.26 apfu F). In zircons from the alkali-feldspar syenites enrichment in P, which is not associated with a simultaneous enrichment in Y + REE, was also observed. Analysed zircons from the high-F, high P₂O₅ Li-mica granites were enriched in Y (up to 5.5 wt. % Y₂O₃; 0.10 apfu Y) and Sc (up to 1.17 wt. % Sc₂O₃; 0.03 apfu Sc).

monazite; xenotime; zircon; granite; Bohemian Massif; Horní Slavkov; Karlovy Vary

Environmental and Earth Sciences, Geochemistry and Petrology

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