Abnormally high-hafnium zircon from rare-metal pegmatites of the Vasin-Mylk deposit, Kola Peninsula

database, nuove specie, discrediti,
ridefinizioni, classificazioni, ecc.
Rispondi
Avatar utente
Marco E. Ciriotti
Messaggi: 31645
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
Contatta:

Abnormally high-hafnium zircon from rare-metal pegmatites of the Vasin-Mylk deposit, Kola Peninsula

Messaggio da Marco E. Ciriotti » dom 17 mar, 2019 12:13

Prossima pubblicazione.

Referenza:
▪ Kudryashov, N.M., Skublov, S.G., Galankina, O.L., Udoratina, O.V., Voloshin, A.V. (2019): Abnormally high-hafnium zircon from rare-metal pegmatites of the Vasin-Mylk deposit (the northeastern part of the Kola Peninsula). Chemie der Erde, 79, (in press).

Abstract:
The deposit Vasin-Mylk is located in NE Kola Peninsula and represents the pegmatites of Li-Cs-Ta specialization (LCT-type). The studied zircon grains from aplitic zone of pegmatites contain av. 0.34-0.45 apfu of Hf, while the rims of grains contain 0.52-0.54 apfu Hf and correspond to hafnon. Zones with high hafnium content are brighter in BSE and CL comparing to central parts of crystals. The crystallization temperatures of high-Hf zircon were estimated as about 550 °C using Ti-in-zircon thermometer. A significant change in crystallization conditions led to isomorphic substitution of Zr by Hf to form hafnon. This change is related to precipitation of aluminous minerals (spodumene, lepidolite) from alumina-oversaturated melt, combined with flux elements (B, Li and F) contributed to the strong fractionation of the Zr/Hf ratio and crystallization of high-Hf zircon at the late («hydrothermal») stage of rare-metal pegmatite evolution. During this stage KDHf between zircon and granitic melt increases rapidly.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

Rispondi

Chi c’è in linea

Visitano il forum: Nessuno e 8 ospiti