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Primitive mantle melting

Started by zhangchang, April 10, 2020, 03:39:14 AM

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zhangchang

Dear Paula,
I finally made up my mind to learn the alphamelts. I have done all the exercises from the website and mantle melting is my interest. However, when I wanna do some melting modelings of the primitive mantle from Mcdonough and Sun 1995, following the same way as the exercise did for DMM, I failed. Especially for the initial entropy, I want to calculate it at 1 bar and 1350 Ã,°C or other temperatures, but everytime I chose option 3, the temperature would change to 1479.41547, and melting results are not good - they started with a liquid_0 mass. Do I miss something?
Best,
Chang

Paula

Dear Chang,

Sorry for the delay in replying. Is this alphaMELTS 1.9? Which version of the exercise are you following for DMM? Can you link to it and/or post your input files for McDonough and Sun 1995, please? You can't upload attachments to the forum but you can copy and paste, or email me if you prefer.

Note that MnO, NiO or P2O5 are not calibrated in pMELTS. Also note that in some of the old examples files there is an "Initial Entropy:" line in the settings file that you need to comment out, and that output was in Kelvin by default in older version of the software and examples.

Best,
Paula

zhangchang

Dear Paula,
Sorry for my delayed reply. I have to move my focus on another project in the last few days.
My alphaMELTS is version 1.9. The entropy calculation problem has been solved. But there exists another one: when everything is ready and then I choose option 4 to do melting calculation, there is a warning jumped out:

...Dropping phase feldspar from the assemblage.
...Adding the solid phase garnet to the assemblage.
...Adding the solid phase orthopyroxene to the assemblage.
Error in redlichKwong(). Bad exit value!
...-->Rank deficiency detected by HFTI, rank = 0 (16)
sh: line 1:  6176 Segmentation fault: 11  "/Users/czhang/Documents/alphamelts/Problem/alphamelts" < /Users/czhang/Documents/alphamelts/Problem/batch.txt
RUN_ALPHAMELTS.COMMAND WARNING: alphamelts may have crashed!

I couldn't find a solution to that.
So, here I post my input file.

Title: Pyrolite (PUM) from McDonough & Sun 1995
Initial Composition: SiO2 44.90
Initial Composition: TiO2 0.20
Initial Composition: Al2O3 4.44
Initial Composition: Cr2O3 0.38
Initial Composition: Fe2O3 0.116
Initial Composition: FeO 7.926
Initial Composition: MnO 0.13
Initial Composition: MgO 37.71
Initial Composition: CaO 3.54
Initial Composition: Na2O 0.36
Initial Composition: NiO 0.25
Initial Temperature: 1350
Initial Pressure: 40000
Log fO2 Path: none
Log fO2 Delta: 0


and my batch file:

1
PM_SM.melts
9
0
2
1350
1
3
0
spinel
olivine
orthopyroxene
clinopyroxene
feldspar
x
7
-1
9
1
2
0
40000
4
0


Thank you for answering.
Best regards, and stay healthy,
Chang

Paula

Hi Chang,

I can't easily help if you are running alphamelts without run_alphamelts.command. How are you setting the environment variables?

4 GPa is a big jump for pMELTS to take. You might find it works better if you make a note of the reference entropy from option 7, and then restart alphaMELTS to impose it. Or after the initial calculation, run up pressure with option 4 in smaller increments (the default is +1000 bars) until you hit 4 GPa. Then use menu option 2 to change DELTAP to something negative and call option 4 again.

Note that MnO and NiO are not calibrated in pMELTS, so you should remove them from the .melts file.

Paula