(2) WHITE MICA problem

[js]

Hi everyone,

I have calculated a pseudosection for metapelite using JUN92d dataset. Interestingly, in this pseudosection some fields contain I guess two different types of white mica. It is shown by (2) WHITE MICA. My question is how to figure out what types of WHITE MICAS they are? In other words how to calculate for example isopleths for them?

Cheers,

Jacek

[opxcpx]

Simplest way if you are curious about the phase and its composition, run theriak at a couple of PT points in the regions where phase occurs. The output should list all phases and thier compositions, very useful, and quick when I have run across something I had not before. Report back what you find. 

Cheers!

[js]

Chris,thank you for your kind advice. It looks as if these two white micas are WHITE_MICA_Ms and WHITE_MICA_Pg. I am a bit surprised as muscovite and paragonite are endmembers of WHITE MICA solid solution. On the other hand in the investigated sample, I have documented both muscovite and paragonite. So, I am confused.

All the best

Jacek

[Erik Duesterhoeft]

Hi Jacek,

please also check the example "Scripts in Domino.ppt" (https://serc.carleton.edu/research_educ ... omino.html). It explains how to plot isopleths of the (2)WHITE_MICA problem. If you want to understand, why you can have two white micas; I recommend to read page 304 and Fig 7.26 of the book "Petrogenesis of Metamorphic rocks" (Bucher and Grapes, 8th Edition), where this  example is explained. To make a long story short: It's a miscibility gap.

cheers,

Erik

[js]

Hi Erik,

thanks for your replay.

cheers,

Jacek