Zirconolite in marble at Krahulov and age of HT/LP metamorphism in the contact aureole of the Třebíč Pluton (Moldanubian zone)Article PDF
Zirconolite in marble at Krahulov and age of HT/LP metamorphism in the contact aureole of the Třebíč Pluton (Moldanubian zone)
Regional-scale contact metamorphism of the Třebíč Pluton led to the formation of distinct zoning manifested typically in dolomite marbles. Inside part of metamorphic aureole appears rare zirconolite as an accessory mineral in clinohumite-spinel-forsterite marble. The zirconolite-bearing assemblage contains calcite, dolomite, hydroxylclinohumite, spinel, forsterite, chlorite, phlogopite, fluorapatite, baddeleyite and ilmenite-geikielite. Zirconolite grains (<200 μm in size) sporadic overgrowth of baddeleyite or comprise its common relic. The chemical composition of zirconolite varies due to complex zoning of Hf (0.67–1.09 wt. % HfO2), Th (0.38–12.76 wt. % ThO2), U (0.11–9.57 wt. % UO2), Fe (0.64–2.88 wt. % Fe2O3), Mg (0.20–1.92 wt. % MgO), Nb (0.56–1.01 wt. % Nb2O5), W (0.38–1.11 wt. % WO3), and Y (0.15–0.84 wt. % Y2O3). The CHIME zirconolite dating yields average age 331 ±11 Ma corresponding to post-peak HT/LP metamorphic phase in marbles and is in good agreement with the age of emplacement of the Třebíč Pluton.
Renata Čopjaková, Czech Geological Survey, Leitnerova 23, 658 69 Brno; and Masaryk University, Kotlářská 2, 611 37 Brno, e-mail: firstname.lastname@example.org
Stanislav Houzar, Department of Mineralogy and Petrography, Moravian Museum, Zelný trh 6, 659 37 Brno, Czech Republic, email@example.com