one of the solid phases has undergone phase separation.

[Olivier]

Hi,

I try to fractionnal crystallize a melt but run into this error message. At higher pressure, raising the initial temperature solved the problem, but at this low pressure (0.3kb) nothing seems to do it...

Any idea?

thank you

Olivier

[Paula]

Hi Olivier,

Sorry I forgot to reply to this before. This is a warning, rather than an error message, and will be displayed whether the modelled phase separation is realistic (e.g. exsolution in inverted pigeonite) or not.

At low pressures and temperatures some solid phases in MELTS, particularly pyroxenes and to a lesser extent feldspars, show more phase miscibility than they should. There is not a lot that can be done about this (it is a reflection on how difficult it is to calibrate the complex behaviour of the pyroxenes for the range of compositions, pressures and temperatures that the MELTS algorithm is used for). Often this manifests itself as one 'normal' looking pyroxene and one rather extreme one (e.g. really titanium-rich) but a weighted sum of the compositions may still compare well with microprobe analyses...

Paula