EGU21-820
https://doi.org/10.5194/egusphere-egu21-820
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Stability relations of monazite-(Ce), gadolinite-(Ce), gadolinite-(Y), britholite-(Ce) and bastnäsite-(Ce) during late- to post-magmatic processes in nepheline syenite (Čistá pluton, Czech Republic)

Maciej Jaranowski1, Bartosz Budzyń1, Gabriela A. Kozub-Budzyń2, Jiří Sláma3, and Josef Klomínský4
Maciej Jaranowski et al.
  • 1Polish Academy of Sciences, Institute of Geological Sciences, Kraków, Poland (ndjarano@cyf-kr.edu.pl)
  • 2AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection, Kraków, Poland
  • 3The Czech Academy of Sciences, Institute of Geology, Prague, Czech Republic
  • 4Czech Geological Survey, Prague, Czech Republic

Stability relations of the REE-bearing accessory phases and alteration processes in the cancrinite-bearing nepheline syenite from the Čistá pluton (the center of the upper-crustal Tepla–Barrandian unit, Bohemian Massif, Czech Republic) were studied. Observations of rock microtextures, quantitative analyses of minerals and compositional X-ray mapping were performed using electron probe microanalysis (EPMA). The primary REE-bearing accessory minerals assemblage includes monazite-(Ce) associated with gadolinite-group minerals (i.e. gadolinite-(Ce) and gadolinite-(Y)), which were partially replaced by britholite-(Ce), bastnäsite-(Ce), aggregates of fine-grained REE-bearing phases (possibly fluorapatite and/or britholite-(Ce)) and, rarely, cerianite. K-feldspar and albite form intergrowths or symplectites with REE-phases in the investigated reaction microtextures. Furthermore, the zircon crystals demonstrate oscillatory zoning and/or extensive patchy zoning due to alteration processes. The alteration of accessory minerals are interpreted as driven by K- and Na-bearing alkali fluids with high CO2 activity during late- to post-magmatic processes.

Acknowledgements: This work was supported by the National Science Centre research grant no. 2017/27/B/ST10/00813.

How to cite: Jaranowski, M., Budzyń, B., Kozub-Budzyń, G. A., Sláma, J., and Klomínský, J.: Stability relations of monazite-(Ce), gadolinite-(Ce), gadolinite-(Y), britholite-(Ce) and bastnäsite-(Ce) during late- to post-magmatic processes in nepheline syenite (Čistá pluton, Czech Republic), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-820, https://doi.org/10.5194/egusphere-egu21-820, 2021.

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