Extreme Alteration of Chevkinite-(Ce) by Pb-CO2-Rich Fluids:Evidence from the White Tundra Pegmatite, Keivy Massif, Kola Peninsula

Macdonald, R. and Bagiński, B. and Stachowicz, M. and Zozulya, D. and Kotowski, J. and Jokubauskas, P. (2022) Extreme Alteration of Chevkinite-(Ce) by Pb-CO2-Rich Fluids:Evidence from the White Tundra Pegmatite, Keivy Massif, Kola Peninsula. Minerals, 12 (8). ISSN 2075-163X

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Abstract

An unusual hydrothermal alteration scheme was presented for chevkinite-(Ce) from the White Tundra pegmatite (2656 ± 5 Ma), Keivy massif, Kola Peninsula. Pb-CO2-rich fluids initially removed REE and Y from the chevkinite-(Ce), with enrichment in Pb and U. PbO abundances reaching 17.35 wt%. Continued alteration resulted in the altered chevkinite-(Ce) being progressively transformed to a Pb-Ti-Fe-Si phase, which proved, upon EBSD analysis, to be almost totally amorphous. Pb enrichment was accompanied by a loss of LREE, especially La, relative to HREE, and the development of strong positive Ce anomalies. A notably U-rich aeschynite-(Y), with UO2 values ≤7.67 wt%, crystallized along with the chevkinite-(Ce). Aeschynite-(Y) with a lower UO2 value (3.91 wt%) and bastnäsite-(Ce) formed during alteration. The formation of bastnäsite-(Ce) rather than cerussite, which might have been expected in a high Pb-CO2 environment, is ascribed to the fluids being acidic. © 2022 by the authors.

Item Type:
Journal Article
Journal or Publication Title:
Minerals
Additional Information:
Export Date: 29 September 2022
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/1900/1909
Subjects:
ID Code:
176821
Deposited By:
Deposited On:
04 Oct 2022 10:30
Refereed?:
Yes
Published?:
Published
Last Modified:
22 Nov 2022 11:54