MAGEMin

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MAGEMin_C.jl: options ​

General options / functionality ​

Name solvus ​

  • When performing calculations, it is usually recommended to use the argument name_solvus = true, e.g.,
julia
out = single_point_minimization(P, T, data, X=X, Xoxides=Xoxides, sys_in=sys_unit, name_solvus = true)

This option checks the composition of the stable solution phases and tries to name them accordingly. For instance, this allows distinguishing feldspar as plagioclase or alkali-feldspar. Details about how solvus phases are named are provided in the Method section.

Solver option ​

  • It is usually best to use the solver option solver = 0 when performing calculations. This is easily activated by initializing MAGEMin_C.jl such as:
julia
data        =   Initialize_MAGEMin("mb", verbose=false, solver = 0);

Buffers ​

  • When using buffers, note that you need to provide enough oxide to oversaturate the system across the whole P-T(-X) range of interest. While this applies to oxygen buffers, it also applies to activity buffers (e.g., aTiO2, aH2O, aSiO2, etc.).

Database dependent choices ​

Metabasite (mb) ​

  • When using the metabasite database (Green et al., 2016), it is important to activate the correct clinopyroxene depending on the temperature conditions. By default, aug (the high-temperature solution model) is active. If you need to use the low-temperature solution model dio instead, you can initialize MAGEMin_C.jl such as:
julia
data        =   Initialize_MAGEMin("mb", verbose=false, mbCpx = 0);

Note

The default value is mbCpx = 1

  • Similarly, mbIlm, mpSp, and mpIlm switch between paired solution models on the metabasite/metapelite databases:
OptionDatabase= 0= 1Default
mbCpxmbOmphacite (dio, low-T)Augite (aug, high-T)1
mbIlmmbIlmenite-hematite (ilmm)Ilmenite (ilm)0
mpSpmpSpinel (sp)Spinel (spl)0
mpIlmmpIlmenite-hematite (ilmm)Ilmenite (ilm)0
julia
data        =   Initialize_MAGEMin("mb", verbose=false, mbIlm = 1);

Warning

None of mbCpx/mbIlm/mpSp/mpIlm apply to the all database - its dispatch deliberately keeps both phase variants each toggle would otherwise switch between as independent, separately selectable phases (e.g. both dio_G16 and aug_G16 are always present). Use select_phases/pp_list=/ss_list= or remove_phases/rm_list= to pick between them there instead.

Selecting which phases to consider ​

Two complementary ways to restrict which pure/solution phases MAGEMin considers during minimization - an exclude-list and an include-list. Use whichever is shorter to write for your case; passing both at once raises an error.

Exclude a list of phases (remove_phases/rm_list=) ​

remove_phases(list, dtb) resolves phase names against the given database and returns an index list (rm_list) to pass to single_point_minimization/multi_point_minimization/ AMR_minimization. See example E.5.

Keep only a list of phases (select_phases/pp_list=/ss_list=) ​

select_phases is the inverse: give it the pure phases (pp_list=) and/or solution phases (ss_list=) you want to keep active, and every other phase in that category is deactivated automatically. pp_list and ss_list are independent - passing only one leaves the other phase category untouched.

julia
data    = Initialize_MAGEMin("mp", verbose=false);
out     = single_point_minimization(P, T, data, X=X, Xoxides=Xoxides, sys_in=sys_in,
                                     ss_list=["liq_W14", "g_W14", "bi_W14"])

is equivalent to writing out the complement by hand with remove_phases, but self-updates if the database's phase list changes. The 13 oxygen-fugacity buffer / fixed-activity pure phases (qfm, mw, qif, nno, hm, iw, cco, aH2O, aO2, aMgO, aFeO, aAl2O3, aTiO2) never need to be listed in pp_list - select_phases always leaves them untouched, since their activation is governed solely by the buffer="..." keyword (see Buffers above), not by phase selection.

Note

select_phases/pp_list=/ss_list= and remove_phases/rm_list= are mutually exclusive on a single call - combining them raises an error rather than silently guessing intent.

Discovering phase names (print_phase_info) ​

Both remove_phases and select_phases need exact phase names, which can be hard to guess for an unfamiliar database (particularly all, with its citation-tagged names like liq_W14 vs liq_G16). print_phase_info(dtb; level=0|1) prints them directly:

julia
print_phase_info("mp")            # database info, solution-phase names, pure-phase names
print_phase_info("mp"; level=1)   # same, plus every solution phase's endmember list