Miniatura

Fitxers

621529.pdf (3.21 MB)

Tipus de document

Article

Versió

Versió publicada

Data de publicació

2012-04-01

Tots els drets reservats

Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/34506

Niobium and rare earth minerals from the Virulundo carbonatite, Namibe, Angola

Títol de la revista

Autors

Director/Tutor

ISSN de la revista

Títol del volum

Recurs relacionat

http://dx.doi.org/10.1180/minmag.2012.076.2.08

Resum

The Virulundo carbonatite in Angola, one of the biggest in the world, contains pyrochlore as an accessory mineral in all of the carbonatite units (calciocarbonatites, ferrocarbonatites, carbonatite breccias, trachytoids). The composition of the primary pyrochlore crystals is very close to fluornatrocalciopyrochlore in all these units. High-temperature hydrothermal processes caused the pseudomorphic replacement of the above crystals by a second generation of pyrochlore, characterized by lower F and Na contents. Low-temperature hydrothermal replacement of the above pyrochlores, associated with production of quartz-carbonates-fluorite veins, controled the development of a third generation of pyrochlore, characterized by high Sr contents. Finally, supergene processes produced the development of a secondary paragenesis in the carbonatite, consisting in late carbonates, goethite, hollandite and REE minerals (mainly synchysite-(Ce), britholite-(Ce), britholite-(La), cerite-(Ce)). Separation of Ce from the other REE was allowed by oxidizing conditions. Therefore, Ce4+ was also incorporated into a late generation of pyrochlore, which is also strongly enriched in Ba and strongly depleted in Ca and Na

Matèries

Jaciments minerals, Angola

Matèries (anglès)

Mineral deposits

Citació

Col·leccions

Articles publicats en revistes (Mineralogia, Petrologia i Geologia Aplicada)

Citació

TORRÓ I ABAT, Lisard, VILLANOVA DE BENAVENT, Cristina, CASTILLO OLIVER, Montgarri, CAMPENY, Marc, GONÇALVES, Antonio olimpio, MELGAREJO I DRAPER, Joan-carles. Niobium and rare earth minerals from the Virulundo carbonatite, Namibe, Angola. _Mineralogical Magazine_. 2012. Vol. 76, núm. 393-409. [consulta: 20 de gener de 2026]. ISSN: 0026-461X. [Disponible a: https://hdl.handle.net/2445/34506]

Exportar metadades

JSON - METS

Compartir registre