Sulfur and REE zoning in apatite: the example of the Colli Albani magmatic system

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Marco E. Ciriotti
Messaggi: 24148
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
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Sulfur and REE zoning in apatite: the example of the Colli Albani magmatic system

Messaggio da Marco E. Ciriotti » mar 27 feb, 2018 17:48

Prossima pubblicazione.

Referenza:
▪ Alessandro, F., Gaeta, M., Carroll, M.R., Petrelli, M. (2018): Sulfur and REE zoning in apatite: the example of the Colli Albani magmatic system. European Journal of Mineralogy, 30, (in press).

Abstract:
We investigate the distribution of major and trace elements in apatite crystals hosted in granular alkaline rocks composed mainly of leucite and clinopyroxene, representative of the hypabyssal crystallization of a magma body in the Quaternary ultra-potassic Colli Albani Volcanic District (CAVD), which was emplaced into thick limestone units along the Tyrrhenian margin of Italy. Results show that the analyzed crystals are the SrO-richest (up to 4.6 wt%) fluorapatite (F = 2.6–3.7 wt%) of the Italian alkaline rocks. The strontium enrichment is caused by the lack of other Sr-compatible mineral phases, such as plagioclase, alkali feldspar and melilite, in these leucite- and clinopyroxene-bearing rocks. The studied samples show core–rim zoning with rims enriched in Si, S, and REE whereas the cores are enriched in Ca and P. The LREE-oxides contents of apatite, reaching 4.2 wt%, represent more than 95% of the total REE budget; SiO2 contents range from 1.3 to 3.6 wt%, and SO3 concentrations between 0.6 and 1.4 wt%.We support the idea that REE and sulfur enrichment are a response to the crystallization caused by the pressure drop in the magmatic system during the eruption and follow the substitution mechanisms Si4+ + REE3+ = P5+ + Ca2+ and S6 + Si4+ = 2P5+. The results also suggest the presence of the substitution Th4+ + 2Si4+ = Ca2+ + 2P5+.
Marco E. Ciriotti

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

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Marco E. Ciriotti
Messaggi: 24148
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
Contatta:

Re: Sulfur and REE zoning in apatite: the example of the Colli Albani magmatic system

Messaggio da Marco E. Ciriotti » gio 03 mag, 2018 17:38

Pubblicazione effettuata.

Referenza:
▪ Alessandro, F., Gaeta, M., Carroll, M.R., Petrelli, M. (2018): Sulfur and REE zoning in apatite: the example of the Colli Albani magmatic system. European Journal of Mineralogy, 30, 125-133.
Marco E. Ciriotti

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

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