pMelts vs. rhyolite-melts for modeling crystallization of ultramafics

[trela]

Hi everyone,

I am wondering which program is better suited (pMELTS or rhyolite-melts) to model fractional crystallization of ultramafic liquids at pressures between 1 atm and 3 GPa? Basically, I'm trying to model the liquid lines of descent (LLDs) for olivine and spinel in the mentioned pressure range. I've done the modeling using both programs. The results are similar, but rhyolite-melts yields spinel LLDs with slightly higher Cr compositions. This is great for me, because this model reproduces my spinel EMP data rather nicely. Is there anything I should be cautious with when using rhyolite-melts for this type of modeling?  Thanks!!

[trela]

Sorry...the pressure range is 1 atm to 2 GPa.

[Paula]

Hi,

Sorry for the delay in replying. For that pressure range you should use rhyolite-MELTS. Don't worry about the name - when quartz and alkali-feldspar are absent, rhyolite-MELTS behaves identically to MELTS. The original MELTS model was calibrated for a wide range of compositions, from ultramafics to rhyolitic etc. (pMELTS in contrast is only suited to peridotite or mafic pyroxenite type compositions.)

Paula

[trela]

Thanks Paula! Much appreciated!

Best,

Jarek Trela