--- Dirk Hellwig <[log in to unmask]>
schrieb: > Dear all,
> the pressure dependent celadonite (reverse
> Tschermak-) substitution in
> white mica (Si content) is often determined to apply
> the phengite
> geobarometer of Massonne&Schreyer (1987, Contrib.
> Min. Pet. 96, 212-224).
> Does somebody recall work performed on/ papers
> dealing with the influence
> of metamorphic fluids on the celadonite-substitution
> or on the (Fe2+,
> Mg)3Al-2 exchange between muscovite and phengite,
> maybe even on a
> quantitative basis. Any leaching effects?
> Your comments are, as always, appreciated,
> cheers
> Dirk
> ***************************************************
> Dirk Hellwig
> Department of Geosciences
> Philipps-University Marburg
> Hans-Meerwein-Strasse
> 35032 Marburg/Germany
> [log in to unmask]
> phone: +49-6421-2823055
> fax: +49-6421-2828919
> http://staff-www.uni-marburg.de/~hellwig/
> ***************************************************
This one may help.
SIMPSON, GHD; THOMPSON, AB & CONNOLLY, JAD (2000):
Phase relations andsingularities in thermbarometry of
metamorphic assemblages containing phengite, chlorite,
biotite, K-feldspar, quartz and H2O.- Contrib Mineral
Petrol 139: 555-569
At least you may find some more literature here.
Personally i would not use Massonne´s
phengit-barometer
in LP-rocks. According to Massonne all influences are
negliable, but i would not bet on that.
Always use a broad beam, when performing EPMA on Ms
and take care of the whole grain. Zonation is quite
common, and also intergrowths as Eric pointed out
already. Some are visible in BSIs.
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