Water solubility in albite-orthoclase join and JR-1 rhyolite melts at 1000 deg-C and 500 to 2000 bars, determined by micro-analysis with SIMS

Isoji Miyagi, Hisayoshi Yurimoto, Eiichi Takahashi

Geochemical Journal
Vol. 31, 57-61 (1997)

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Abstract:

  Water solubilities in albite (Ab)-orthclase (Or) join and JR-1
rhyolite melts at 1000 deg-C and up to 2000 bars were determined by
the "excess of water" method using an internally heated pressure
vessel (IHPV) with rapid quenching and a secondary ion microprobe mass 
spectrometer (SIMS).  We have found that secondary hydration of run
product glass with coexisting aqueous fluid occurs during quenching.
The hydration is significant in sodium-rich glass.  The bulk analysis
of such secondary hydrated run-products will cause overestimation of
the water solubility, while the true water solubility can be obtained
by micro-analysis on non-attacked portion of the glass.  The apparent
compositional dependence in the published water solubility data could
be due to the secondary hydration of run product glass.  Newly
determined water solubility for the Ab-Or join and rhyolitic melts is
expressed as H2O (mol. %) = 0.19 sqrt(PH2O) (bar), at 1000 deg-C.