I considered that, but didn't want to bother him if it is a common
problem that others have already solved. It is easy for anyone who
is too busy at the moment to ignore a post to an e-mail list without
feeling guilty, even if they could have answered the question, but if
a letter is written directly to an individual it feels, to me, like
more of an imposition, which is why I tried the list first.
At 03:40 2/02/2009, you wrote:
> You should e-mail Jamie directly.
>On Jan 31, 2009, at 10:21 PM, Reia M. Chmielowski wrote:
>>I have been using Perple_X for my thermodynamic modeling, and have
>>been frustrated by differences in the predictions in different sort
>>of calculations. the two types in question are designated in the
>>"in" file as "calculation type 5" (what I think of as the "normal"
>>calculations--this is the one for which I enter a bulk rock
>>composition give it a P/T range of interest and obtain
>>"pseduosections") and "calculation type 7" (which I call "path"
>>calculations--this is the one for which I enter the same bulk rock
>>composition, give it a relationship between temperature and pressure
>>and tell it the range of pressure (or T) of interest, and which
>>mineral(s) should fractionate over time). It seems to me that, in
>>theory, the first "step" in the "path" for calculation type 7 should
>>predict minerals of the exact same composition at a given P/T as was
>>predicted in calculation type 5 for that P/T.
>>I have been using calculation type 5 first, using the resultant
>>graphs and the "werami" program to determine the P/T at whcih
>>garnets are predicted to have the same composition as those measured
>>in my garnet cores, and then trying to use type calculation type 7
>>to calculate P/T paths over which garnet composition changes with
>>fractionation such that they achieve the same composition as those
>>measured in my garnet rims. However, this is complicated because
>>often (always?) the predicted composition of garnet at the first
>>step of the path doesn't match what was predicted by the type 5
>>calculations for that P/T. (The amount by which it doesn't match
>>seems to vary) Has anyone else faced this complication? If so,
>>have you found a way to get that path calculations to start with the
>>same composition of garnet (or whatever mineral you told it to
>>fractionate)? Am I doing something wrong? Am I being unreasonable
>>to want them to be the same? How different can they be and still
>>have results that are "useable"?
>>Reia M. Chmielowski
>>Department of Earth Sciences/CODES
>>University of Tasmania, Australia
>>(03) 6239 6666
>>0408 238 590
Reia M. Chmielowski
Department of Earth Sciences/CODES
University of Tasmania, Australia
(03) 6239 6666
0408 238 590