Zircon and whole-rock Zr/Hf ratios as markers of the evolution of granitic magmas: Examples from the Teplice caldera (Czech Republic/Germany)

0477204 - GLÚ 2018 RIV AT eng J - Journal Article
Breiter, Karel - Škoda, R.
Zircon and whole-rock Zr/Hf ratios as markers of the evolution of granitic magmas: Examples from the Teplice caldera (Czech Republic/Germany).
Mineralogy and Petrology. Roč. 111, č. 4 (2017), s. 435-457. ISSN 0930-0708. E-ISSN 1438-1168
R&D Projects: GA ČR GA14-13600S
Institutional support: RVO:67985831
Keywords : Zr/Hf value * zircon * Teplice caldera * rhyolite * rare-metal granite * Cínovec deposit
OECD category: Mineralogy
Impact factor: 1.664, year: 2017

Hafnium contents and Zr/Hf ratios were studied in zircons and their parent rocks from three magmatic suites associated with the Teplice caldera, Eastern Erzgebirge: rhyolite and dacite from the peraluminous Schönfeld Unit, relatively younger A-type Teplice rhyolite, and post-caldera A-type biotite and zinnwaldite granite and greisen. New data suggest that zircon crystallizing from a geochemically less evolved volatile- and water-poor melt is, compared to the host rock, relatively Hf-depleted, while zircon crystallizing from an evolved volatile- and water-rich melt has a Zr/Hf value approximately identical to that of the parental melt. Zr/Hf values in zircon did not change substantially either during greisenization, or during low-temperature alteration after metamictization. Zr/Hf values in the whole rock may serve as a sensitive indicator of magmatic fractionation of evolved granitic melts, as they are only negligibly influenced by the following hydrothermal processes. Zr/Hf values in individual cogenetic zircon grains are scattered but their general evolution trend in the rock series is consistent with the evolution of the whole-rock Zr/Hf values.
Permanent Link: http://hdl.handle.net/11104/0273578