PTMafic (v. 2.0)

Software package for thermometry, barometry, and activity calculations in mafic rocks using an IBM or compatible computer

J.I. Soto and V.M. Soto
 

PTMAFIC (v. 2.0) is a program for compatible personal computers with minimum hardware requirements, that can be used in thermometric and barometric calculations by petrologists concerned with the determination of P-T paths in mafic and ultramafic rocks. The program creates ASCII files of normalized chemical analyses of amphiboles, garnet, epidote, ilmenite, muscovite, pyroxenes (ortho- and clinopyroxene), olivine, plagioclase and spinel. The program carries out a wide range of stoichiometric and thermodynamic calculations on these minerals, such as cation site-allocations at the different structural positions, the obtaining of molar fractions and mole percent of the end-member terms, and the application of different thermodynamic models for calculation of activity coefficients and activities. The program contains calibrations published for 13 geothermometers and 12 geobarometers (see below) applicable to mafic and ultramafic rocks that cover metamorphic conditions, ranging from granulite and eclogite facies to green-schist facies.

References

American Mineralogist, 1993, vol. 78, 840-844.
Computers & Geosciences, 1995 , vol. 21 , 619-652.

Hardware requirements of the program

PTMAFIC version 2.0 has been developed for IBM and PC computers running under MSDOS (version 3.0 and higher) and DRDOS operating systems. It can be run with no difficulty in DOS sessions under Windows interface or OS/2 system operating. The program requires a minimum of 640 Kb RAM, CGA or higher video card (EGA; VGA, SuperVGA), color or monochrome screen, and microprocessor of the 80086 family (80286, 80386, 80486). Hard disk program installation requires at least 500 Kb free space, although it can also be run from a 3.5 in. floppy diskette.

Summary Description

The program consists of four basic operations (Main menu, Geothermometers, Geobarometers and Activities), each of which has a pull-down menu containing the different options for that operation.

• Activities menu

This menu allows the operator to obtain, for amphiboles, garnet, olivine, ilmenite, plagioclase, pyroxenes, and spinel the distribution of the cations at the different sites following the proposed models of cation-site assignments, mole fractions at the different sites (X_i), mole percent of the end-members, Margules parameters (W), activity coefficients (g) and thermodynamic activities (a) according to different models of activity-composition relations for mineral solid solutions (e.g. ideal vs. non-ideal solid solutions).

• Geothermometers menu

The 13 geothermometers included in PTMAFIC are: amphibole-garnet, amphibole-plagioclase, clinopyroxene-garnet, clinopyroxene-olivine, clinopyroxene-olivine-spinel, clionopyroxene-orthopyroxene, garnet-ilmenite, garnet-muscovite, garnet-orthopyroxene, olivine-spinel, Ca-Al and Cr-Al in orthopyroxene, orthopyroxene-olivine, and orthopyroxene-olivine-spinel.

• Geobarometers menu

This version of the program contains the following 12 barometers: Al-in-amphibole, Amphibole-chlorite, epidote-plagioclase, amphibole-garnet-plagioclase-quartz, clinopyroxene-plagioclase-quartz, garnet-clinopyroxene-orthopyroxene-plagioclase-quartz, garnet-clinopyroxene-plagioclase-quartz, garnet-olivine-plagioclase, garnet-othopyroxene, garnet-orthopyroxene-plagioclase-quartz, garnet-rutile-ilmenite-quartz, Jd-in clinopyroxene, and phengite.

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