Hi,
You should use a buffer. There must be a hematite-magnetite buffer define in both database JUN92.bs (Berman) and tcdb55c2d (Holland & Powell). Check in the database if you have something like this defined:
(in tcdb55c2d)
OHM-BUFFER O(2) OHM *OHM
ST 0.000 000000.000 000.000000 0.000000
CP1 0.000000 0.00000 0.00 0.0
COM hematite[6]magnetite[-4] 0 hematite
-OHM-BUFFER O(-2) -OHM *OHM
ST 0.000 000000.000 000.000000 0.000000
CP1 0.000000 0.00000 0.00 0.0
COM OHM-BUFFER[-1]
(in JUN92.bs)
HMO-BUFFER O(2) HMO *HMO
ST 0.000 000000.000 000.000000 0.000000
CP1 0.000000 0.00000 0.00 0.0
COM HEMATITE[6]MAGNETITE[-4] 0 HEMATITE
-HMO-BUFFER O(-2) -HMO *HMO
ST 0.000 000000.000 000.000000 0.000000
CP1 0.000000 0.00000 0.00 0.0
COM HMO-BUFFER[-1]
To use one of these, type something like this in the THERIN file:
0 SI(10)AL(10)FE(20)O(?) *,HMO
where HMO is your hematite-magnetite buffer (using JUN92.bs) or type HHM if you are using tcdb55c2d. Check the documentation for details on the use of a buffer. I guess this should work, even if you do not specify the oxygen (i.e. using O(?) it should calculate the right amount of oxygen based on the HM-buffer).
Julien
On Oct 26, 2011, at 11:40 AM, Tapabrato Sarkar wrote:
Dear All,
I am working on silica undersaturated, oxidized Fe rich migmatitic metapelites containing about 10% ilmenite and hercynite spinel having haematite and magnetite exolution respectively. I am trying to make the pseudo section of these rocks using THERIAK-DOMINO software. These rocks have high ferric iron content as indicated by the presence of magnetite and haematite. Till now I have calculated the pseudo sections with unspecified oxygen values (putting O(?)), where the program calculates the oxygen values on its own (as far as I know). I think it is not the right way to deal with oxidized Fe rich rocks as the oxidized Fe phases are not appearing in the pseudo sections. But I do not know how to specify the oxygen values for the rocks. I have tried with arbitrary high oxygen values and it gives strange results.
I would be glad if somebody helps me with literature and suggestions in this regard.
Thanks in advance
Tapabrato Sarkar
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TAPABRATO SARKAR
Research Scholar
Institut für GeowissenschaftenLudewig-Meyn-Str. 10
Universität Kiel
24118 Kiel, Germany
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