Chemical and Textural Peculiarities of Zircon from Peralkaline Granites and Quartz-Bearing Syenites

0582818 - GLÚ 2025 RIV CH eng J - Journal Article
Breiter, Karel - Kynický, J. - Korbelová, Zuzana
Chemical and Textural Peculiarities of Zircon from Peralkaline Granites and Quartz-Bearing Syenites.
Minerals. Roč. 14, č. 2 (2024), č. článku 187. E-ISSN 2075-163X
Institutional support: RVO:67985831
Keywords : peralkaline rocks * zircon chemistry * Khan Bogd * Khalzan Buregte * Ivigtut * Madeira
OECD category: Mineralogy
Impact factor: 2.5, year: 2022
Method of publishing: Open access
https://www.mdpi.com/2075-163X/14/2/187

Zircon from four plutons of peralkaline granites and quartz-bearing syenites, differing in geotectonic positions, petrological and mineralogical compositions, and contents of volatile and trace elements, was studied using SEM, CL, and EPMA with the intention to define typical textural and chemical features of zircon from peralkaline rocks. In strongly peralkaline Na-pyroxene-bearing rocks represented by the Khan Bogd and Khalzan Buregte plutons (Mongolia), the primary zircon is scarce or missing. Most zircon grains are secondary, originating in hydrothermal stage from primary Zr silicates. They often form globular or radial aggregates. Chemical compositions of zircon in these rocks typically show high contents of Y, moderate contents of REE (thus high Y/Yb values) together with low contents of U and Th and low analytical totals. In mildly peralkaline mica-bearing rocks represented by Ivigtut stock (Groenland) and Madeira pluton (Brazil), the exclusive primary Zr mineral is zircon, mostly of orthomagmatic origin. Its analytical totals approach 100 wt%, enrichment in HREE, resulting in low Y/Yb values, is typical. Zircon populations from two types of peralkaline granitoids can be distinguished from each other and from zircon from S-type granites based on combination of the Zr/Hf, Y/Yb, and U/Th values, or on the Y-Hf-P ternary diagram.
Permanent Link: https://hdl.handle.net/11104/0350865