Title
Phosphate Petrochronology of the Belcina REE Mineralization (Ditrău Alkaline Massif, Romania)
Author
Jolanta Burda
Institute of Earth Sciences, Faculty of Natural Sciences, University of Silesia in Katowice
Paul Tibuleac
Department of Geology, University Alexandru Ioan Cuza of Iasi
Abstract
A notable REE mineralization in Europe is associated with the Ditrău Alkaline Massif (DAM) in the Eastern Carpathians (Romania). It is an expression of the latest hydrothermal phase in the DAM and is found in the form of mineralized carbonate veins cross-cutting the complex in the NW (Jolotca region) and the SE (Belcina region) parts of the DAM. In the Belcina veins monazite-(Ce), xenotime-(Y) and apatite, together with Fe-Mg-rich carbonate, thorite, thorogummite, gedrite and plagioclase are rock-forming. Three different textural and chemical types of the monazite-(Ce) and the xenotime-(Y) document a three-stage evolution. The relative phosphate age succession (from older to younger) thereby is xnt1 > xnt2 (>)+ mnz1 + Fe2O3 + Fe-gedrite > mnz2 + Fe-dolomite (+ plagioclase) > mnz3 + xnt3 + apatite. Phosphate chemistry shows that these crystallized from hydrothermal fluids, whereby each phosphate type follows a separate evolutionary path suggesting growth from (at least) three independent and successive hydrothermal fluids. Chemistry and pathways within the DAM suggest that these hydrothermal fluids could be derived from a subsurface carbonatitic intrusion. Mnz1,2 and xnt1,2 ages are tightly clustered at 215.8 ± 0.7 Ma (Norian, Upper Triassic). The third-generation phosphate ages are younger, but are associated with large analytical uncertainties and did not deliver geologically useful ages. The mean age of ca. 216 Ma is interpreted as the timing of the Belcina REE mineralization, which together with the fluid chemistry, supports a model of the presence of a late-stage, independent carbonatitic intrusion about 10 Ma after the main igneous activity (ca. 235–225 Ma) forming the DAM, synchronous with extension-related magmatism in the region.
Keywords
phosphate petrochronologyDitrău Alkaline MassifEastern CarpathiansREE mineralizationmetasomatismhydrothermal fluids
Object type
Language
English [eng]
Persistent identifier
Appeared in
Title
Minerals
Volume
13
Issue
6
ISSN
2075-163X
Issued
2023
Publication
MDPI AG
Version type
Date issued
2023
Access rights
Rights
Rights statement
© 2023 by the authors
University of Vienna | Universitätsring 1 | 1010 Vienna | T
+43-1-4277-0