Phosphate Petrochronology of the Belcina REE Mineralization (Ditrău Alkaline Massif, Romania)

Autor(en)

Urs Klötzli, Jolanta Burda, Paul Tibuleac

Abstrakt

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.

Organisation(en)

Department für Lithosphärenforschung

Externe Organisation(en)

University of Silesia in Katowice, Universitatea „Alexandru Ioan Cuza“ Iași

Journal

Minerals

Band

13

ISSN

2075-163X

DOI

https://doi.org/10.3390/min13060739

Publikationsdatum

06-2023

Peer-reviewed

Ja

ÖFOS 2012

105127 Geochronologie, 105105 Geochemie, 105116 Mineralogie

Schlagwörter

ASJC Scopus Sachgebiete

Geotechnical Engineering and Engineering Geology, Geology

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/69755693-1178-41ba-9890-22562ea04e70