From trace element to major element

[jschools]

I'm doing some calculations involving melting along an adiabat, then taking the resulting melt and crystallizing it along a PT path representative of the lithosphere. I'm using regular MELTS for both calculations (looking at Jupiter's small moon Io, so I don't need the pressure range of pMELTS). I am having some problems with potassium (K₂O) as a major element in the initial calculations at depth, as its presence crashes the calculation. It works fine with K as a trace element.

Since I am doing a two part calculation, can I simply have K as a trace element in the first melting calculation, and convert it back to a major element K₂O before the crystallization calculation? When I tested this out almost all the trace K went into the melt (as I would have expected) so this seems like a valid thing to do, but I wanted to check and see if there's something I'm missing that would make this unwise.

Thanks,
Joe

[Paula]

Hi Joe,

Apologies for the delay in replying - I was at a DCO workshop. Your approach sounds fine to me, as there are few solid phases for K₂O to go into in the MELTS system. It is how I would do the calculation!

Cheers,
Paula

[jschools]

Thank you!

Joe