Hi all,
Reiner makes a good point, perhaps not all fluid inclusions all
created equal. On the other hand, simply because a fluid inclusion
is in garnet, I do not think it is safe to assume that is has
preserved a pristine sample of the peak metamorphic fluid. Garnets
sometimes contain mineral inclusions that are not in equilibrium (at
peak metamorphic P-T) with other minerals in the same sample. In a
few cases (reported in the literature on granulite metamorphism),
these same garnets also contain CO2-rich fluid inclusions. If the
mineral inclusions in the garnet are not in equilibrium with the
other phases in the same rock at the peak of metamorphism, then
perhaps the fluid inclusions in this garnet should not be used to
infer peak metamorphic fluid compositions.
I should probably add that Julie Vry and Phil Brown published a
paper describing fluid inclusions in garnet. According to their
interpretation, these fluid inclusions formed during prograde
metamorphism. Perhaps this is another example of fluid inclusions in
garnets from granulite facies rocks that do not contain pristine
samples of the peak metamorphic fluid.
Cheers, Will
>Hi John,
> agreed - if you are referring to high-T fluid inclusion studies in quartz.
>However in combination with mineral equilibria, fluid inclusions in other
>peak metamorphic minerals such as garnet or sillimanite are an important
>tool to constrain the peak metamorphic fluid chemistry and give insight in
>fluid-rock interaction during peak conditions. Maybe its the only
>straightforward way ....
>Cheers,
>Reiner
>>
>******************************
>Reiner Klemd
>Professor fuer Geochemie
>und Lagerstaettenkunde
>Institut fuer Mineralogie
>Universitaet Wuerzburg
>Am Hubland
>97074 Wuerzburg
>
>Tel.: 0931/8885412 Fax.: 0931/8884620
>**************************************
--
----------------------------------------------------
Will Lamb
Associate Professor
Department of Geology and Geophysics
Texas A&M University
College Station, TX 77843-3115
U.S.A.
Office Telephone: (979) 845-3075
Fax: (979) 845-6162
email: [log in to unmask]
http://geoweb.tamu.edu/
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