And F-Rich Zircon from Fractionated Perphosphorous Granites: the Peraluminous Podlesı´ Granite System, Czech Republic
Lithos 88 (2006) 15–34 www.elsevier.com/locate/lithos Extreme P-, Bi-, Nb-, Sc-, U- and F-rich zircon from fractionated perphosphorous granites: The peraluminous Podlesı´ granite system, Czech Republic Karel Breiter a,*, Hans-Ju¨rgen Fo¨rster b, Radek Sˇkoda c a Czech Geological Survey, Geologicka´ 6, CZ-15200 Praha 5, Czech Republic b Institute of Earth Sciences, University of Potsdam, P.O. Box 601553, D-14415 Potsdam, Germany c Institute of Earth Sciences, Masaryk University, Kotla´rˇska´ 2, CZ-61137 Brno, Czech Republic Received 15 December 2004; accepted 16 August 2005 Available online 22 November 2005 Abstract The strongly peraluminous and P-rich, protolithionite and zinnwaldite leucogranites from Podlesı´, western Krusˇne´ Hory Mts., Czech Republic, contain accessory zircon with extraordinary enrichment of several elements, which constitute trace elements in common zircon. Elements showing a not yet reported anomalous enrichment include P (up to 20.2 wt.% P2O5; equivalent to 0.60 apfu, formula calculated on the basis of 4 oxygen atoms), Bi (up to 9.0 wt.% Bi2O3; 0.086 apfu), Nb (up to 6.7 wt.% Nb2O5, 0.12 apfu), Sc (up to 3.45 wt.% Sc2O3; 0.10 apfu), U (up to 14.8 wt.% UO2; 0.12 apfu) and F (up to 3.81 wt.% F; 0.42 apfu). Strong enrichment of P preferentially involved the berlinite-type substitution (2 Si4+ ZP5+ +Al3+) implying that significant Al may enter the Si position in zircon. Incorporation of other exotic elements is primarily governed by the xenotime (Si4+ +Zr4+ ZP5+ +Y3+), pretulite (Sc3+ +P5+ ZZr4+ +Si4+), brabantite-type (Ca2+ +(U, Th)4+ +2P5+ Z2Zr4+ +2Si4+), and ximengite-type (Bi3+ +P5+ ZZr4+ +Si4+) substitution reactions.
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